Commit Graph

1991 Commits

Author SHA1 Message Date
Peter Zijlstra 8b700983de sched: Remove sched_set_*() return value
Ingo suggested that since the new sched_set_*() functions are
implemented using the 'nocheck' variants, they really shouldn't ever
fail, so remove the return value.

Cc: axboe@kernel.dk
Cc: daniel.lezcano@linaro.org
Cc: sudeep.holla@arm.com
Cc: airlied@redhat.com
Cc: broonie@kernel.org
Cc: paulmck@kernel.org
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
2020-06-15 14:10:26 +02:00
Peter Zijlstra 7318d4cc14 sched: Provide sched_set_fifo()
SCHED_FIFO (or any static priority scheduler) is a broken scheduler
model; it is fundamentally incapable of resource management, the one
thing an OS is actually supposed to do.

It is impossible to compose static priority workloads. One cannot take
two well designed and functional static priority workloads and mash
them together and still expect them to work.

Therefore it doesn't make sense to expose the priority field; the
kernel is fundamentally incapable of setting a sensible value, it
needs systems knowledge that it doesn't have.

Take away sched_setschedule() / sched_setattr() from modules and
replace them with:

  - sched_set_fifo(p); create a FIFO task (at prio 50)
  - sched_set_fifo_low(p); create a task higher than NORMAL,
	which ends up being a FIFO task at prio 1.
  - sched_set_normal(p, nice); (re)set the task to normal

This stops the proliferation of randomly chosen, and irrelevant, FIFO
priorities that dont't really mean anything anyway.

The system administrator/integrator, whoever has insight into the
actual system design and requirements (userspace) can set-up
appropriate priorities if and when needed.

Cc: airlied@redhat.com
Cc: alexander.deucher@amd.com
Cc: awalls@md.metrocast.net
Cc: axboe@kernel.dk
Cc: broonie@kernel.org
Cc: daniel.lezcano@linaro.org
Cc: gregkh@linuxfoundation.org
Cc: hannes@cmpxchg.org
Cc: herbert@gondor.apana.org.au
Cc: hverkuil@xs4all.nl
Cc: john.stultz@linaro.org
Cc: nico@fluxnic.net
Cc: paulmck@kernel.org
Cc: rafael.j.wysocki@intel.com
Cc: rmk+kernel@arm.linux.org.uk
Cc: sudeep.holla@arm.com
Cc: tglx@linutronix.de
Cc: ulf.hansson@linaro.org
Cc: wim@linux-watchdog.org
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-15 14:10:20 +02:00
Linus Torvalds a9429089d3 RAS updates from Borislav Petkov:
* Unmap a whole guest page if an MCE is encountered in it to avoid
     follow-on MCEs leading to the guest crashing, by Tony Luck.
 
     This change collided with the entry changes and the merge resolution
     would have been rather unpleasant. To avoid that the entry branch was
     merged in before applying this. The resulting code did not change
     over the rebase.
 
   * AMD MCE error thresholding machinery cleanup and hotplug sanitization, by
     Thomas Gleixner.
 
   * Change the MCE notifiers to denote whether they have handled the error
     and not break the chain early by returning NOTIFY_STOP, thus giving the
     opportunity for the later handlers in the chain to see it. By Tony Luck.
 
   * Add AMD family 0x17, models 0x60-6f support, by Alexander Monakov.
 
   * Last but not least, the usual round of fixes and improvements.
 -----BEGIN PGP SIGNATURE-----
 
 iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAl7j5m0THHRnbHhAbGlu
 dXRyb25peC5kZQAKCRCmGPVMDXSYoXyMD/9GneajFaI5D0F59/btEGAx1X0PTDz1
 LrGf79Y5NqSJrzggsnrdFzsGjJNcQ2KbfSgs9fhdsvvvIpK+YqZ+rVFAg7DcKc2n
 RwHd+X3TluKsc4oCuagZli7R4HHO5P9hbkHY6DD++F0eeMblLhNnq1hGUSdoENHN
 HFsZapQpvlpn3IYN1e07lFBVvujRL/pBez7tmhh6bPxmcLZFCBrIHuAXz7dbzz0Y
 BjhVRLNq6+9Yztvrt8uIgc1EAoMfprkY6nVtvkxC5gmVor3orkRC4rRNc/+jhgDK
 p0s1JxDgb3SNN79no9wvQaqRNs/rNlAx6xSA0gmW+SbxrFEsk6cUp1BVVRr031dk
 /QGedvpJzK7PjCX+d7Jvy+391q1YEsdnbQhXRdjSXQf+DihWm98O++wDodw9kgwt
 FgkZD4qICT3xtpGs1bqDgrm220g8d27nGjsXlvFfyVYAQAlE2vcx0NqySOTT7NeT
 Zu6GIvGcGCObJT2JTWbPkvbm2aNYXzYNZGRBLlEzy7qFXuVG4aKR6W1L6uSW3SmK
 UUo/F3KHgZWM/h1PyMbxzAvu60eojBcEXva8jDxBv0GCDJhzFV3yOVdgxrLPpGcZ
 7EqiUtTrxvxGOFjpFFaZRiT0R89ZfvOxVyXGwMX8zph9NyPLSj9MspyQSkhFFREz
 0FAfy/7wqDfMRg==
 =iWiy
 -----END PGP SIGNATURE-----

Merge tag 'ras-core-2020-06-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 RAS updates from Thomas Gleixner:
 "RAS updates from Borislav Petkov:

   - Unmap a whole guest page if an MCE is encountered in it to avoid
     follow-on MCEs leading to the guest crashing, by Tony Luck.

     This change collided with the entry changes and the merge
     resolution would have been rather unpleasant. To avoid that the
     entry branch was merged in before applying this. The resulting code
     did not change over the rebase.

   - AMD MCE error thresholding machinery cleanup and hotplug
     sanitization, by Thomas Gleixner.

   - Change the MCE notifiers to denote whether they have handled the
     error and not break the chain early by returning NOTIFY_STOP, thus
     giving the opportunity for the later handlers in the chain to see
     it. By Tony Luck.

   - Add AMD family 0x17, models 0x60-6f support, by Alexander Monakov.

   - Last but not least, the usual round of fixes and improvements"

* tag 'ras-core-2020-06-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  x86/mce/dev-mcelog: Fix -Wstringop-truncation warning about strncpy()
  x86/{mce,mm}: Unmap the entire page if the whole page is affected and poisoned
  EDAC/amd64: Add AMD family 17h model 60h PCI IDs
  hwmon: (k10temp) Add AMD family 17h model 60h PCI match
  x86/amd_nb: Add AMD family 17h model 60h PCI IDs
  x86/mcelog: Add compat_ioctl for 32-bit mcelog support
  x86/mce: Drop bogus comment about mce.kflags
  x86/mce: Fixup exception only for the correct MCEs
  EDAC: Drop the EDAC report status checks
  x86/mce: Add mce=print_all option
  x86/mce: Change default MCE logger to check mce->kflags
  x86/mce: Fix all mce notifiers to update the mce->kflags bitmask
  x86/mce: Add a struct mce.kflags field
  x86/mce: Convert the CEC to use the MCE notifier
  x86/mce: Rename "first" function as "early"
  x86/mce/amd, edac: Remove report_gart_errors
  x86/mce/amd: Make threshold bank setting hotplug robust
  x86/mce/amd: Cleanup threshold device remove path
  x86/mce/amd: Straighten CPU hotplug path
  x86/mce/amd: Sanitize thresholding device creation hotplug path
  ...
2020-06-13 10:21:00 -07:00
Thomas Gleixner 37d1a04b13 Rebase locking/kcsan to locking/urgent
Merge the state of the locking kcsan branch before the read/write_once()
and the atomics modifications got merged.

Squash the fallout of the rebase on top of the read/write once and atomic
fallback work into the merge. The history of the original branch is
preserved in tag locking-kcsan-2020-06-02.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2020-06-11 20:02:46 +02:00
Tony Luck 17fae1294a x86/{mce,mm}: Unmap the entire page if the whole page is affected and poisoned
An interesting thing happened when a guest Linux instance took a machine
check. The VMM unmapped the bad page from guest physical space and
passed the machine check to the guest.

Linux took all the normal actions to offline the page from the process
that was using it. But then guest Linux crashed because it said there
was a second machine check inside the kernel with this stack trace:

do_memory_failure
    set_mce_nospec
         set_memory_uc
              _set_memory_uc
                   change_page_attr_set_clr
                        cpa_flush
                             clflush_cache_range_opt

This was odd, because a CLFLUSH instruction shouldn't raise a machine
check (it isn't consuming the data). Further investigation showed that
the VMM had passed in another machine check because is appeared that the
guest was accessing the bad page.

Fix is to check the scope of the poison by checking the MCi_MISC register.
If the entire page is affected, then unmap the page. If only part of the
page is affected, then mark the page as uncacheable.

This assumes that VMMs will do the logical thing and pass in the "whole
page scope" via the MCi_MISC register (since they unmapped the entire
page).

  [ bp: Adjust to x86/entry changes. ]

Fixes: 284ce4011b ("x86/memory_failure: Introduce {set, clear}_mce_nospec()")
Reported-by: Jue Wang <juew@google.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jue Wang <juew@google.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200520163546.GA7977@agluck-desk2.amr.corp.intel.com
2020-06-11 15:19:17 +02:00
Andrey Konovalov 5ff3b30ab5 kcov: collect coverage from interrupts
This change extends kcov remote coverage support to allow collecting
coverage from soft interrupts in addition to kernel background threads.

To collect coverage from code that is executed in softirq context, a part
of that code has to be annotated with kcov_remote_start/stop() in a
similar way as how it is done for global kernel background threads.  Then
the handle used for the annotations has to be passed to the
KCOV_REMOTE_ENABLE ioctl.

Internally this patch adjusts the __sanitizer_cov_trace_pc() compiler
inserted callback to not bail out when called from softirq context.
kcov_remote_start/stop() are updated to save/restore the current per task
kcov state in a per-cpu area (in case the softirq came when the kernel was
already collecting coverage in task context).  Coverage from softirqs is
collected into pre-allocated per-cpu areas, whose size is controlled by
the new CONFIG_KCOV_IRQ_AREA_SIZE.

[andreyknvl@google.com: turn current->kcov_softirq into unsigned int to fix objtool warning]
  Link: http://lkml.kernel.org/r/841c778aa3849c5cb8c3761f56b87ce653a88671.1585233617.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Marco Elver <elver@google.com>
Link: http://lkml.kernel.org/r/469bd385c431d050bc38a593296eff4baae50666.1584655448.git.andreyknvl@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-04 19:06:20 -07:00
Linus Torvalds 039aeb9deb ARM:
- Move the arch-specific code into arch/arm64/kvm
 - Start the post-32bit cleanup
 - Cherry-pick a few non-invasive pre-NV patches
 
 x86:
 - Rework of TLB flushing
 - Rework of event injection, especially with respect to nested virtualization
 - Nested AMD event injection facelift, building on the rework of generic code
 and fixing a lot of corner cases
 - Nested AMD live migration support
 - Optimization for TSC deadline MSR writes and IPIs
 - Various cleanups
 - Asynchronous page fault cleanups (from tglx, common topic branch with tip tree)
 - Interrupt-based delivery of asynchronous "page ready" events (host side)
 - Hyper-V MSRs and hypercalls for guest debugging
 - VMX preemption timer fixes
 
 s390:
 - Cleanups
 
 Generic:
 - switch vCPU thread wakeup from swait to rcuwait
 
 The other architectures, and the guest side of the asynchronous page fault
 work, will come next week.
 -----BEGIN PGP SIGNATURE-----
 
 iQFIBAABCAAyFiEE8TM4V0tmI4mGbHaCv/vSX3jHroMFAl7VJcYUHHBib256aW5p
 QHJlZGhhdC5jb20ACgkQv/vSX3jHroPf6QgAq4wU5wdd1lTGz/i3DIhNVJNJgJlp
 ozLzRdMaJbdbn5RpAK6PEBd9+pt3+UlojpFB3gpJh2Nazv2OzV4yLQgXXXyyMEx1
 5Hg7b4UCJYDrbkCiegNRv7f/4FWDkQ9dx++RZITIbxeskBBCEI+I7GnmZhGWzuC4
 7kj4ytuKAySF2OEJu0VQF6u0CvrNYfYbQIRKBXjtOwuRK4Q6L63FGMJpYo159MBQ
 asg3B1jB5TcuGZ9zrjL5LkuzaP4qZZHIRs+4kZsH9I6MODHGUxKonrkablfKxyKy
 CFK+iaHCuEXXty5K0VmWM3nrTfvpEjVjbMc7e1QGBQ5oXsDM0pqn84syRg==
 =v7Wn
 -----END PGP SIGNATURE-----

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm updates from Paolo Bonzini:
 "ARM:
   - Move the arch-specific code into arch/arm64/kvm

   - Start the post-32bit cleanup

   - Cherry-pick a few non-invasive pre-NV patches

  x86:
   - Rework of TLB flushing

   - Rework of event injection, especially with respect to nested
     virtualization

   - Nested AMD event injection facelift, building on the rework of
     generic code and fixing a lot of corner cases

   - Nested AMD live migration support

   - Optimization for TSC deadline MSR writes and IPIs

   - Various cleanups

   - Asynchronous page fault cleanups (from tglx, common topic branch
     with tip tree)

   - Interrupt-based delivery of asynchronous "page ready" events (host
     side)

   - Hyper-V MSRs and hypercalls for guest debugging

   - VMX preemption timer fixes

  s390:
   - Cleanups

  Generic:
   - switch vCPU thread wakeup from swait to rcuwait

  The other architectures, and the guest side of the asynchronous page
  fault work, will come next week"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (256 commits)
  KVM: selftests: fix rdtsc() for vmx_tsc_adjust_test
  KVM: check userspace_addr for all memslots
  KVM: selftests: update hyperv_cpuid with SynDBG tests
  x86/kvm/hyper-v: Add support for synthetic debugger via hypercalls
  x86/kvm/hyper-v: enable hypercalls regardless of hypercall page
  x86/kvm/hyper-v: Add support for synthetic debugger interface
  x86/hyper-v: Add synthetic debugger definitions
  KVM: selftests: VMX preemption timer migration test
  KVM: nVMX: Fix VMX preemption timer migration
  x86/kvm/hyper-v: Explicitly align hcall param for kvm_hyperv_exit
  KVM: x86/pmu: Support full width counting
  KVM: x86/pmu: Tweak kvm_pmu_get_msr to pass 'struct msr_data' in
  KVM: x86: announce KVM_FEATURE_ASYNC_PF_INT
  KVM: x86: acknowledgment mechanism for async pf page ready notifications
  KVM: x86: interrupt based APF 'page ready' event delivery
  KVM: introduce kvm_read_guest_offset_cached()
  KVM: rename kvm_arch_can_inject_async_page_present() to kvm_arch_can_dequeue_async_page_present()
  KVM: x86: extend struct kvm_vcpu_pv_apf_data with token info
  Revert "KVM: async_pf: Fix #DF due to inject "Page not Present" and "Page Ready" exceptions simultaneously"
  KVM: VMX: Replace zero-length array with flexible-array
  ...
2020-06-03 15:13:47 -07:00
Linus Torvalds d479c5a191 The changes in this cycle are:
- Optimize the task wakeup CPU selection logic, to improve scalability and
    reduce wakeup latency spikes
 
  - PELT enhancements
 
  - CFS bandwidth handling fixes
 
  - Optimize the wakeup path by remove rq->wake_list and replacing it with ->ttwu_pending
 
  - Optimize IPI cross-calls by making flush_smp_call_function_queue()
    process sync callbacks first.
 
  - Misc fixes and enhancements.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAl7WPL0RHG1pbmdvQGtl
 cm5lbC5vcmcACgkQEnMQ0APhK1i0ThAAs0fbvMzNJ5SWFdwOQ4KZIlA+Im4dEBMK
 sx/XAZqa/hGxvkm1jS0RDVQl1V1JdOlru5UF4C42ctnAFGtBBHDriO5rn9oCpkSw
 DAoLc4eZqzldIXN6sDZ0xMtC14Eu15UAP40OyM4qxBc4GqGlOnnale6Vhn+n+pLQ
 jAuZlMJIkmmzeA6cuvtultevrVh+QUqJ/5oNUANlTER4OM48umjr5rNTOb8cIW53
 9K3vbS3nmqSvJuIyqfRFoMy5GFM6+Jj2+nYuq8aTuYLEtF4qqWzttS3wBzC9699g
 XYRKILkCK8ZP4RB5Ps/DIKj6maZGZoICBxTJEkIgXujJlxlKKTD3mddk+0LBXChW
 Ijznanxn67akoAFpqi/Dnkhieg7cUrE9v1OPRS2J0xy550synSPFcSgOK3viizga
 iqbjptY4scUWkCwHQNjABerxc7MWzrwbIrRt+uNvCaqJLweUh0GnEcV5va8R+4I8
 K20XwOdrzuPLo5KdDWA/BKOEv49guHZDvoykzlwMlR3gFfwHS/UsjzmSQIWK3gZG
 9OMn8ibO2f1OzhRcEpDLFzp7IIj6NJmPFVSW+7xHyL9/vTveUx3ZXPLteb2qxJVP
 BYPsduVx8YeGRBlLya0PJriB23ajQr0lnHWo15g0uR9o/0Ds1ephcymiF3QJmCaA
 To3CyIuQN8M=
 =C2OP
 -----END PGP SIGNATURE-----

Merge tag 'sched-core-2020-06-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:
 "The changes in this cycle are:

   - Optimize the task wakeup CPU selection logic, to improve
     scalability and reduce wakeup latency spikes

   - PELT enhancements

   - CFS bandwidth handling fixes

   - Optimize the wakeup path by remove rq->wake_list and replacing it
     with ->ttwu_pending

   - Optimize IPI cross-calls by making flush_smp_call_function_queue()
     process sync callbacks first.

   - Misc fixes and enhancements"

* tag 'sched-core-2020-06-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
  irq_work: Define irq_work_single() on !CONFIG_IRQ_WORK too
  sched/headers: Split out open-coded prototypes into kernel/sched/smp.h
  sched: Replace rq::wake_list
  sched: Add rq::ttwu_pending
  irq_work, smp: Allow irq_work on call_single_queue
  smp: Optimize send_call_function_single_ipi()
  smp: Move irq_work_run() out of flush_smp_call_function_queue()
  smp: Optimize flush_smp_call_function_queue()
  sched: Fix smp_call_function_single_async() usage for ILB
  sched/core: Offload wakee task activation if it the wakee is descheduling
  sched/core: Optimize ttwu() spinning on p->on_cpu
  sched: Defend cfs and rt bandwidth quota against overflow
  sched/cpuacct: Fix charge cpuacct.usage_sys
  sched/fair: Replace zero-length array with flexible-array
  sched/pelt: Sync util/runnable_sum with PELT window when propagating
  sched/cpuacct: Use __this_cpu_add() instead of this_cpu_ptr()
  sched/fair: Optimize enqueue_task_fair()
  sched: Make scheduler_ipi inline
  sched: Clean up scheduler_ipi()
  sched/core: Simplify sched_init()
  ...
2020-06-03 13:06:42 -07:00
Linus Torvalds 94709049fb Merge branch 'akpm' (patches from Andrew)
Merge updates from Andrew Morton:
 "A few little subsystems and a start of a lot of MM patches.

  Subsystems affected by this patch series: squashfs, ocfs2, parisc,
  vfs. With mm subsystems: slab-generic, slub, debug, pagecache, gup,
  swap, memcg, pagemap, memory-failure, vmalloc, kasan"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (128 commits)
  kasan: move kasan_report() into report.c
  mm/mm_init.c: report kasan-tag information stored in page->flags
  ubsan: entirely disable alignment checks under UBSAN_TRAP
  kasan: fix clang compilation warning due to stack protector
  x86/mm: remove vmalloc faulting
  mm: remove vmalloc_sync_(un)mappings()
  x86/mm/32: implement arch_sync_kernel_mappings()
  x86/mm/64: implement arch_sync_kernel_mappings()
  mm/ioremap: track which page-table levels were modified
  mm/vmalloc: track which page-table levels were modified
  mm: add functions to track page directory modifications
  s390: use __vmalloc_node in stack_alloc
  powerpc: use __vmalloc_node in alloc_vm_stack
  arm64: use __vmalloc_node in arch_alloc_vmap_stack
  mm: remove vmalloc_user_node_flags
  mm: switch the test_vmalloc module to use __vmalloc_node
  mm: remove __vmalloc_node_flags_caller
  mm: remove both instances of __vmalloc_node_flags
  mm: remove the prot argument to __vmalloc_node
  mm: remove the pgprot argument to __vmalloc
  ...
2020-06-02 12:21:36 -07:00
NeilBrown a37b0715dd mm/writeback: replace PF_LESS_THROTTLE with PF_LOCAL_THROTTLE
PF_LESS_THROTTLE exists for loop-back nfsd (and a similar need in the
loop block driver and callers of prctl(PR_SET_IO_FLUSHER)), where a
daemon needs to write to one bdi (the final bdi) in order to free up
writes queued to another bdi (the client bdi).

The daemon sets PF_LESS_THROTTLE and gets a larger allowance of dirty
pages, so that it can still dirty pages after other processses have been
throttled.  The purpose of this is to avoid deadlock that happen when
the PF_LESS_THROTTLE process must write for any dirty pages to be freed,
but it is being thottled and cannot write.

This approach was designed when all threads were blocked equally,
independently on which device they were writing to, or how fast it was.
Since that time the writeback algorithm has changed substantially with
different threads getting different allowances based on non-trivial
heuristics.  This means the simple "add 25%" heuristic is no longer
reliable.

The important issue is not that the daemon needs a *larger* dirty page
allowance, but that it needs a *private* dirty page allowance, so that
dirty pages for the "client" bdi that it is helping to clear (the bdi
for an NFS filesystem or loop block device etc) do not affect the
throttling of the daemon writing to the "final" bdi.

This patch changes the heuristic so that the task is not throttled when
the bdi it is writing to has a dirty page count below below (or equal
to) the free-run threshold for that bdi.  This ensures it will always be
able to have some pages in flight, and so will not deadlock.

In a steady-state, it is expected that PF_LOCAL_THROTTLE tasks might
still be throttled by global threshold, but that is acceptable as it is
only the deadlock state that is interesting for this flag.

This approach of "only throttle when target bdi is busy" is consistent
with the other use of PF_LESS_THROTTLE in current_may_throttle(), were
it causes attention to be focussed only on the target bdi.

So this patch
 - renames PF_LESS_THROTTLE to PF_LOCAL_THROTTLE,
 - removes the 25% bonus that that flag gives, and
 - If PF_LOCAL_THROTTLE is set, don't delay at all unless the
   global and the local free-run thresholds are exceeded.

Note that previously realtime threads were treated the same as
PF_LESS_THROTTLE threads.  This patch does *not* change the behvaiour
for real-time threads, so it is now different from the behaviour of nfsd
and loop tasks.  I don't know what is wanted for realtime.

[akpm@linux-foundation.org: coding style fixes]
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Chuck Lever <chuck.lever@oracle.com>	[nfsd]
Cc: Christoph Hellwig <hch@lst.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Link: http://lkml.kernel.org/r/87ftbf7gs3.fsf@notabene.neil.brown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-02 10:59:08 -07:00
Peter Zijlstra a148866489 sched: Replace rq::wake_list
The recent commit: 90b5363acd ("sched: Clean up scheduler_ipi()")
got smp_call_function_single_async() subtly wrong. Even though it will
return -EBUSY when trying to re-use a csd, that condition is not
atomic and still requires external serialization.

The change in ttwu_queue_remote() got this wrong.

While on first reading ttwu_queue_remote() has an atomic test-and-set
that appears to serialize the use, the matching 'release' is not in
the right place to actually guarantee this serialization.

The actual race is vs the sched_ttwu_pending() call in the idle loop;
that can run the wakeup-list without consuming the CSD.

Instead of trying to chain the lists, merge them.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200526161908.129371594@infradead.org
2020-05-28 10:54:16 +02:00
Ingo Molnar 58ef57b16d Merge branch 'core/rcu' into sched/core, to pick up dependency
We are going to rely on the loosening of RCU callback semantics,
introduced by this commit:

  806f04e9fd2c: ("rcu: Allow for smp_call_function() running callbacks from idle")

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-05-28 10:52:53 +02:00
Peter Zijlstra 5567d11c21 x86/mce: Send #MC singal from task work
Convert #MC over to using task_work_add(); it will run the same code
slightly later, on the return to user path of the same exception.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134100.957390899@linutronix.de
2020-05-19 15:51:19 +02:00
Peter Zijlstra c86e9b987c lockdep: Prepare for noinstr sections
Force inlining and prevent instrumentation of all sorts by marking the
functions which are invoked from low level entry code with 'noinstr'.

Split the irqflags tracking into two parts. One which does the heavy
lifting while RCU is watching and the final one which can be invoked after
RCU is turned off.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134100.484532537@linutronix.de
2020-05-19 15:47:21 +02:00
Thomas Gleixner 2a0a24ebb4 sched: Make scheduler_ipi inline
Now that the scheduler IPI is trivial and simple again there is no point to
have the little function out of line. This simplifies the effort of
constraining the instrumentation nicely.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134058.453581595@linutronix.de
2020-05-12 17:10:49 +02:00
Paul E. McKenney 276c410448 rcu-tasks: Split ->trc_reader_need_end
This commit splits ->trc_reader_need_end by using the rcu_special union.
This change permits readers to check to see if a memory barrier is
required without any added overhead in the common case where no such
barrier is required.  This commit also adds the read-side checking.
Later commits will add the machinery to properly set the new
->trc_reader_special.b.need_mb field.

This commit also makes rcu_read_unlock_trace_special() tolerate nested
read-side critical sections within interrupt and NMI handlers.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-04-27 11:03:52 -07:00
Paul E. McKenney d5f177d35c rcu-tasks: Add an RCU Tasks Trace to simplify protection of tracing hooks
Because RCU does not watch exception early-entry/late-exit, idle-loop,
or CPU-hotplug execution, protection of tracing and BPF operations is
needlessly complicated.  This commit therefore adds a variant of
Tasks RCU that:

o	Has explicit read-side markers to allow finite grace periods in
	the face of in-kernel loops for PREEMPT=n builds.  These markers
	are rcu_read_lock_trace() and rcu_read_unlock_trace().

o	Protects code in the idle loop, exception entry/exit, and
	CPU-hotplug code paths.  In this respect, RCU-tasks trace is
	similar to SRCU, but with lighter-weight readers.

o	Avoids expensive read-side instruction, having overhead similar
	to that of Preemptible RCU.

There are of course downsides:

o	The grace-period code can send IPIs to CPUs, even when those
	CPUs are in the idle loop or in nohz_full userspace.  This is
	mitigated by later commits.

o	It is necessary to scan the full tasklist, much as for Tasks RCU.

o	There is a single callback queue guarded by a single lock,
	again, much as for Tasks RCU.  However, those early use cases
	that request multiple grace periods in quick succession are
	expected to do so from a single task, which makes the single
	lock almost irrelevant.  If needed, multiple callback queues
	can be provided using any number of schemes.

Perhaps most important, this variant of RCU does not affect the vanilla
flavors, rcu_preempt and rcu_sched.  The fact that RCU Tasks Trace
readers can operate from idle, offline, and exception entry/exit in no
way enables rcu_preempt and rcu_sched readers to do so.

The memory ordering was outlined here:
https://lore.kernel.org/lkml/20200319034030.GX3199@paulmck-ThinkPad-P72/

This effort benefited greatly from off-list discussions of BPF
requirements with Alexei Starovoitov and Andrii Nakryiko.  At least
some of the on-list discussions are captured in the Link: tags below.
In addition, KCSAN was quite helpful in finding some early bugs.

Link: https://lore.kernel.org/lkml/20200219150744.428764577@infradead.org/
Link: https://lore.kernel.org/lkml/87mu8p797b.fsf@nanos.tec.linutronix.de/
Link: https://lore.kernel.org/lkml/20200225221305.605144982@linutronix.de/
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andriin@fb.com>
[ paulmck: Apply feedback from Steve Rostedt and Joel Fernandes. ]
[ paulmck: Decrement trc_n_readers_need_end upon IPI failure. ]
[ paulmck: Fix locking issue reported by rcutorture. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-04-27 11:03:51 -07:00
Lai Jiangshan f0bdf6d473 rcu: Remove unused ->rcu_read_unlock_special.b.deferred_qs field
The ->rcu_read_unlock_special.b.deferred_qs field is set to true in
rcu_read_unlock_special() but never set to false.  This is not
particularly useful, so this commit removes this field.

The only possible justification for this field is to ease debugging
of RCU deferred quiscent states, but the combination of the other
->rcu_read_unlock_special fields plus ->rcu_blocked_node and of course
->rcu_read_lock_nesting should cover debugging needs.  And if this last
proves incorrect, this patch can always be reverted, along with the
required setting of ->rcu_read_unlock_special.b.deferred_qs to false
in rcu_preempt_deferred_qs_irqrestore().

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-04-27 11:03:50 -07:00
Ingo Molnar 3b02a051d2 Linux 5.7-rc1
-----BEGIN PGP SIGNATURE-----
 
 iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAl6TbaUeHHRvcnZhbGRz
 QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGhgkH/iWpiKvosA20HJjC
 rBqYeJPxQsgZTuBieWJ+MeVxbpcF7RlM4c+glyvg3QJhHwIEG58dl6LBrQbAyBAR
 aFHNojr1iAYOruVCGnU3pA008YZiwUIDv/ZQ4DF8fmIU2vI2mJ6qHBv3XDl4G2uR
 Nwz8Eu9AgIwZM5coomVOSmoWyFy7Vxmb7W+3t5VmKsvOWx4ib9kyQtOIkvQDEl7j
 XCbWfI0xDQr6LFOm4jnCi5R/LhJ2LIqqIvHHrunbpszM8IwK797jCXz4im+dmd5Y
 +km46N7a8pDqri36xXz1gdBAU3eG7Pt1NyvfjwRVTdX4GquQ2MT0GoojxbLxUP3y
 3pEsQuE=
 =whbL
 -----END PGP SIGNATURE-----

Merge tag 'v5.7-rc1' into locking/kcsan, to resolve conflicts and refresh

Resolve these conflicts:

	arch/x86/Kconfig
	arch/x86/kernel/Makefile

Do a minor "evil merge" to move the KCSAN entry up a bit by a few lines
in the Kconfig to reduce the probability of future conflicts.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-13 09:44:39 +02:00
Linus Torvalds d987ca1c6b Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull exec/proc updates from Eric Biederman:
 "This contains two significant pieces of work: the work to sort out
  proc_flush_task, and the work to solve a deadlock between strace and
  exec.

  Fixing proc_flush_task so that it no longer requires a persistent
  mount makes improvements to proc possible. The removal of the
  persistent mount solves an old regression that that caused the hidepid
  mount option to only work on remount not on mount. The regression was
  found and reported by the Android folks. This further allows Alexey
  Gladkov's work making proc mount options specific to an individual
  mount of proc to move forward.

  The work on exec starts solving a long standing issue with exec that
  it takes mutexes of blocking userspace applications, which makes exec
  extremely deadlock prone. For the moment this adds a second mutex with
  a narrower scope that handles all of the easy cases. Which makes the
  tricky cases easy to spot. With a little luck the code to solve those
  deadlocks will be ready by next merge window"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (25 commits)
  signal: Extend exec_id to 64bits
  pidfd: Use new infrastructure to fix deadlocks in execve
  perf: Use new infrastructure to fix deadlocks in execve
  proc: io_accounting: Use new infrastructure to fix deadlocks in execve
  proc: Use new infrastructure to fix deadlocks in execve
  kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve
  kernel: doc: remove outdated comment cred.c
  mm: docs: Fix a comment in process_vm_rw_core
  selftests/ptrace: add test cases for dead-locks
  exec: Fix a deadlock in strace
  exec: Add exec_update_mutex to replace cred_guard_mutex
  exec: Move exec_mmap right after de_thread in flush_old_exec
  exec: Move cleanup of posix timers on exec out of de_thread
  exec: Factor unshare_sighand out of de_thread and call it separately
  exec: Only compute current once in flush_old_exec
  pid: Improve the comment about waiting in zap_pid_ns_processes
  proc: Remove the now unnecessary internal mount of proc
  uml: Create a private mount of proc for mconsole
  uml: Don't consult current to find the proc_mnt in mconsole_proc
  proc: Use a list of inodes to flush from proc
  ...
2020-04-02 11:22:17 -07:00
Eric W. Biederman d1e7fd6462 signal: Extend exec_id to 64bits
Replace the 32bit exec_id with a 64bit exec_id to make it impossible
to wrap the exec_id counter.  With care an attacker can cause exec_id
wrap and send arbitrary signals to a newly exec'd parent.  This
bypasses the signal sending checks if the parent changes their
credentials during exec.

The severity of this problem can been seen that in my limited testing
of a 32bit exec_id it can take as little as 19s to exec 65536 times.
Which means that it can take as little as 14 days to wrap a 32bit
exec_id.  Adam Zabrocki has succeeded wrapping the self_exe_id in 7
days.  Even my slower timing is in the uptime of a typical server.
Which means self_exec_id is simply a speed bump today, and if exec
gets noticably faster self_exec_id won't even be a speed bump.

Extending self_exec_id to 64bits introduces a problem on 32bit
architectures where reading self_exec_id is no longer atomic and can
take two read instructions.  Which means that is is possible to hit
a window where the read value of exec_id does not match the written
value.  So with very lucky timing after this change this still
remains expoiltable.

I have updated the update of exec_id on exec to use WRITE_ONCE
and the read of exec_id in do_notify_parent to use READ_ONCE
to make it clear that there is no locking between these two
locations.

Link: https://lore.kernel.org/kernel-hardening/20200324215049.GA3710@pi3.com.pl
Fixes: 2.3.23pre2
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2020-04-01 12:04:24 -05:00
Linus Torvalds 642e53ead6 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle are:

   - Various NUMA scheduling updates: harmonize the load-balancer and
     NUMA placement logic to not work against each other. The intended
     result is better locality, better utilization and fewer migrations.

   - Introduce Thermal Pressure tracking and optimizations, to improve
     task placement on thermally overloaded systems.

   - Implement frequency invariant scheduler accounting on (some) x86
     CPUs. This is done by observing and sampling the 'recent' CPU
     frequency average at ~tick boundaries. The CPU provides this data
     via the APERF/MPERF MSRs. This hopefully makes our capacity
     estimates more precise and keeps tasks on the same CPU better even
     if it might seem overloaded at a lower momentary frequency. (As
     usual, turbo mode is a complication that we resolve by observing
     the maximum frequency and renormalizing to it.)

   - Add asymmetric CPU capacity wakeup scan to improve capacity
     utilization on asymmetric topologies. (big.LITTLE systems)

   - PSI fixes and optimizations.

   - RT scheduling capacity awareness fixes & improvements.

   - Optimize the CONFIG_RT_GROUP_SCHED constraints code.

   - Misc fixes, cleanups and optimizations - see the changelog for
     details"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (62 commits)
  threads: Update PID limit comment according to futex UAPI change
  sched/fair: Fix condition of avg_load calculation
  sched/rt: cpupri_find: Trigger a full search as fallback
  kthread: Do not preempt current task if it is going to call schedule()
  sched/fair: Improve spreading of utilization
  sched: Avoid scale real weight down to zero
  psi: Move PF_MEMSTALL out of task->flags
  MAINTAINERS: Add maintenance information for psi
  psi: Optimize switching tasks inside shared cgroups
  psi: Fix cpu.pressure for cpu.max and competing cgroups
  sched/core: Distribute tasks within affinity masks
  sched/fair: Fix enqueue_task_fair warning
  thermal/cpu-cooling, sched/core: Move the arch_set_thermal_pressure() API to generic scheduler code
  sched/rt: Remove unnecessary push for unfit tasks
  sched/rt: Allow pulling unfitting task
  sched/rt: Optimize cpupri_find() on non-heterogenous systems
  sched/rt: Re-instate old behavior in select_task_rq_rt()
  sched/rt: cpupri_find: Implement fallback mechanism for !fit case
  sched/fair: Fix reordering of enqueue/dequeue_task_fair()
  sched/fair: Fix runnable_avg for throttled cfs
  ...
2020-03-30 17:01:51 -07:00
Sebastian Andrzej Siewior 40db173965 lockdep: Add hrtimer context tracing bits
Set current->irq_config = 1 for hrtimers which are not marked to expire in
hard interrupt context during hrtimer_init(). These timers will expire in
softirq context on PREEMPT_RT.

Setting this allows lockdep to differentiate these timers. If a timer is
marked to expire in hard interrupt context then the timer callback is not
supposed to acquire a regular spinlock instead of a raw_spinlock in the
expiry callback.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.534508206@linutronix.de
2020-03-21 16:00:24 +01:00
Peter Zijlstra de8f5e4f2d lockdep: Introduce wait-type checks
Extend lockdep to validate lock wait-type context.

The current wait-types are:

	LD_WAIT_FREE,		/* wait free, rcu etc.. */
	LD_WAIT_SPIN,		/* spin loops, raw_spinlock_t etc.. */
	LD_WAIT_CONFIG,		/* CONFIG_PREEMPT_LOCK, spinlock_t etc.. */
	LD_WAIT_SLEEP,		/* sleeping locks, mutex_t etc.. */

Where lockdep validates that the current lock (the one being acquired)
fits in the current wait-context (as generated by the held stack).

This ensures that there is no attempt to acquire mutexes while holding
spinlocks, to acquire spinlocks while holding raw_spinlocks and so on. In
other words, its a more fancy might_sleep().

Obviously RCU made the entire ordeal more complex than a simple single
value test because RCU can be acquired in (pretty much) any context and
while it presents a context to nested locks it is not the same as it
got acquired in.

Therefore its necessary to split the wait_type into two values, one
representing the acquire (outer) and one representing the nested context
(inner). For most 'normal' locks these two are the same.

[ To make static initialization easier we have the rule that:
  .outer == INV means .outer == .inner; because INV == 0. ]

It further means that its required to find the minimal .inner of the held
stack to compare against the outer of the new lock; because while 'normal'
RCU presents a CONFIG type to nested locks, if it is taken while already
holding a SPIN type it obviously doesn't relax the rules.

Below is an example output generated by the trivial test code:

  raw_spin_lock(&foo);
  spin_lock(&bar);
  spin_unlock(&bar);
  raw_spin_unlock(&foo);

 [ BUG: Invalid wait context ]
 -----------------------------
 swapper/0/1 is trying to lock:
 ffffc90000013f20 (&bar){....}-{3:3}, at: kernel_init+0xdb/0x187
 other info that might help us debug this:
 1 lock held by swapper/0/1:
  #0: ffffc90000013ee0 (&foo){+.+.}-{2:2}, at: kernel_init+0xd1/0x187

The way to read it is to look at the new -{n,m} part in the lock
description; -{3:3} for the attempted lock, and try and match that up to
the held locks, which in this case is the one: -{2,2}.

This tells that the acquiring lock requires a more relaxed environment than
presented by the lock stack.

Currently only the normal locks and RCU are converted, the rest of the
lockdep users defaults to .inner = INV which is ignored. More conversions
can be done when desired.

The check for spinlock_t nesting is not enabled by default. It's a separate
config option for now as there are known problems which are currently
addressed. The config option allows to identify these problems and to
verify that the solutions found are indeed solving them.

The config switch will be removed and the checks will permanently enabled
once the vast majority of issues has been addressed.

[ bigeasy: Move LD_WAIT_FREE,… out of CONFIG_LOCKDEP to avoid compile
	   failure with CONFIG_DEBUG_SPINLOCK + !CONFIG_LOCKDEP]
[ tglx: Add the config option ]

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200321113242.427089655@linutronix.de
2020-03-21 16:00:24 +01:00
Ingo Molnar a4654e9bde Merge branch 'x86/kdump' into locking/kcsan, to resolve conflicts
Conflicts:
	arch/x86/purgatory/Makefile

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-03-21 09:24:41 +01:00
Yafang Shao 1066d1b697 psi: Move PF_MEMSTALL out of task->flags
The task->flags is a 32-bits flag, in which 31 bits have already been
consumed. So it is hardly to introduce other new per process flag.
Currently there're still enough spaces in the bit-field section of
task_struct, so we can define the memstall state as a single bit in
task_struct instead.
This patch also removes an out-of-date comment pointed by Matthew.

Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lkml.kernel.org/r/1584408485-1921-1-git-send-email-laoar.shao@gmail.com
2020-03-20 13:06:19 +01:00
Vincent Guittot 9f68395333 sched/pelt: Add a new runnable average signal
Now that runnable_load_avg has been removed, we can replace it by a new
signal that will highlight the runnable pressure on a cfs_rq. This signal
track the waiting time of tasks on rq and can help to better define the
state of rqs.

At now, only util_avg is used to define the state of a rq:
  A rq with more that around 80% of utilization and more than 1 tasks is
  considered as overloaded.

But the util_avg signal of a rq can become temporaly low after that a task
migrated onto another rq which can bias the classification of the rq.

When tasks compete for the same rq, their runnable average signal will be
higher than util_avg as it will include the waiting time and we can use
this signal to better classify cfs_rqs.

The new runnable_avg will track the runnable time of a task which simply
adds the waiting time to the running time. The runnable _avg of cfs_rq
will be the /Sum of se's runnable_avg and the runnable_avg of group entity
will follow the one of the rq similarly to util_avg.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: "Dietmar Eggemann <dietmar.eggemann@arm.com>"
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Link: https://lore.kernel.org/r/20200224095223.13361-9-mgorman@techsingularity.net
2020-02-24 11:36:36 +01:00
Vincent Guittot 0dacee1bfa sched/pelt: Remove unused runnable load average
Now that runnable_load_avg is no more used, we can remove it to make
space for a new signal.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: "Dietmar Eggemann <dietmar.eggemann@arm.com>"
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Link: https://lore.kernel.org/r/20200224095223.13361-8-mgorman@techsingularity.net
2020-02-24 11:36:36 +01:00
Linus Torvalds 83fa805bcb threads-v5.6
-----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCXjFo8wAKCRCRxhvAZXjc
 omaGAQDVwCHQekqxp2eC8EJH4Pkt+Bn1BLrA25stlTo93YBPHgEAsPVUCRNcrZAl
 VncYmxCfpt3Yu0S/MTVXu5xrRiIXPQk=
 =uqTN
 -----END PGP SIGNATURE-----

Merge tag 'threads-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull thread management updates from Christian Brauner:
 "Sargun Dhillon over the last cycle has worked on the pidfd_getfd()
  syscall.

  This syscall allows for the retrieval of file descriptors of a process
  based on its pidfd. A task needs to have ptrace_may_access()
  permissions with PTRACE_MODE_ATTACH_REALCREDS (suggested by Oleg and
  Andy) on the target.

  One of the main use-cases is in combination with seccomp's user
  notification feature. As a reminder, seccomp's user notification
  feature was made available in v5.0. It allows a task to retrieve a
  file descriptor for its seccomp filter. The file descriptor is usually
  handed of to a more privileged supervising process. The supervisor can
  then listen for syscall events caught by the seccomp filter of the
  supervisee and perform actions in lieu of the supervisee, usually
  emulating syscalls. pidfd_getfd() is needed to expand its uses.

  There are currently two major users that wait on pidfd_getfd() and one
  future user:

   - Netflix, Sargun said, is working on a service mesh where users
     should be able to connect to a dns-based VIP. When a user connects
     to e.g. 1.2.3.4:80 that runs e.g. service "foo" they will be
     redirected to an envoy process. This service mesh uses seccomp user
     notifications and pidfd to intercept all connect calls and instead
     of connecting them to 1.2.3.4:80 connects them to e.g.
     127.0.0.1:8080.

   - LXD uses the seccomp notifier heavily to intercept and emulate
     mknod() and mount() syscalls for unprivileged containers/processes.
     With pidfd_getfd() more uses-cases e.g. bridging socket connections
     will be possible.

   - The patchset has also seen some interest from the browser corner.
     Right now, Firefox is using a SECCOMP_RET_TRAP sandbox managed by a
     broker process. In the future glibc will start blocking all signals
     during dlopen() rendering this type of sandbox impossible. Hence,
     in the future Firefox will switch to a seccomp-user-nofication
     based sandbox which also makes use of file descriptor retrieval.
     The thread for this can be found at
     https://sourceware.org/ml/libc-alpha/2019-12/msg00079.html

  With pidfd_getfd() it is e.g. possible to bridge socket connections
  for the supervisee (binding to a privileged port) and taking actions
  on file descriptors on behalf of the supervisee in general.

  Sargun's first version was using an ioctl on pidfds but various people
  pushed for it to be a proper syscall which he duely implemented as
  well over various review cycles. Selftests are of course included.
  I've also added instructions how to deal with merge conflicts below.

  There's also a small fix coming from the kernel mentee project to
  correctly annotate struct sighand_struct with __rcu to fix various
  sparse warnings. We've received a few more such fixes and even though
  they are mostly trivial I've decided to postpone them until after -rc1
  since they came in rather late and I don't want to risk introducing
  build warnings.

  Finally, there's a new prctl() command PR_{G,S}ET_IO_FLUSHER which is
  needed to avoid allocation recursions triggerable by storage drivers
  that have userspace parts that run in the IO path (e.g. dm-multipath,
  iscsi, etc). These allocation recursions deadlock the device.

  The new prctl() allows such privileged userspace components to avoid
  allocation recursions by setting the PF_MEMALLOC_NOIO and
  PF_LESS_THROTTLE flags. The patch carries the necessary acks from the
  relevant maintainers and is routed here as part of prctl()
  thread-management."

* tag 'threads-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  prctl: PR_{G,S}ET_IO_FLUSHER to support controlling memory reclaim
  sched.h: Annotate sighand_struct with __rcu
  test: Add test for pidfd getfd
  arch: wire up pidfd_getfd syscall
  pid: Implement pidfd_getfd syscall
  vfs, fdtable: Add fget_task helper
2020-01-29 19:38:34 -08:00
Madhuparna Bhowmik 913292c97d sched.h: Annotate sighand_struct with __rcu
This patch fixes the following sparse errors by annotating the
sighand_struct with __rcu

kernel/fork.c:1511:9: error: incompatible types in comparison expression
kernel/exit.c💯19: error: incompatible types in comparison expression
kernel/signal.c:1370:27: error: incompatible types in comparison expression

This fix introduces the following sparse error in signal.c due to
checking the sighand pointer without rcu primitives:

kernel/signal.c:1386:21: error: incompatible types in comparison expression

This new sparse error is also fixed in this patch.

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20200124045908.26389-1-madhuparnabhowmik10@gmail.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2020-01-26 10:54:47 +01:00
Ingo Molnar 837171fe77 Linux 5.5-rc7
-----BEGIN PGP SIGNATURE-----
 
 iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAl4k7i8eHHRvcnZhbGRz
 QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGvk0IAKRenVOdiudY77SQ
 VZjsteyrYTTQtPPv494ToIRjR0XQ+gYp8vyWzXTUC5Nm9Y9U3VzDqUPUjWszrSXE
 6mU+tzcMc9qwuUxnIFn8zfg64ygw+37sn/w3xqeH4QmF9Z5Wl3EX3SdXTs7jp3RS
 VxiztkUNI5ZBV2GDtla5K/9qLPqCQnUYXIiyi5lAtBtiitZDVXFp7dy7hMgEiaEO
 +78K5Kh3xlt5ndDsBFOlwIb2Oof3KL7bBXntdbSBc/bjol6IRvAgln48HWCv59G2
 jzAp2tj2KobX9GRAEPj+v4TQZEW0SXDNDi8MgQsM+3DYVCTmANsv57CBKRuf01+F
 nB1kAys=
 =zSnJ
 -----END PGP SIGNATURE-----

Merge tag 'v5.5-rc7' into locking/kcsan, to refresh the tree

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-01-20 08:42:47 +01:00
Ingo Molnar 28336be568 Linux 5.5-rc4
-----BEGIN PGP SIGNATURE-----
 
 iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAl4JNtkeHHRvcnZhbGRz
 QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGdN0H/3UI6LHOx1ol3/7L
 TwgMibg2pNxNU05bowDjQt92+Hgj9JM0TeFBsfr5hLaeKBgeVCPr5xK/vH09NlKu
 otVGbhBLpl9OAUu9znTfbt4bcqhJKlr/K0mS5e1vPsXvZ3wdHS27trwjgyu16/pP
 NJwkcs5/VRYVC/SrZay2NvheKN+DoGSd4+ZlJprwtAAVMdbEvoaGqRLGKLfLeDMc
 Z04w8AKhnKIxSkt+eEmuW9+pAQJUAkk4QVjixcJe8q0QpA1XIj965yvE8+XpjbLo
 eFxupmZq4S2JdCjsa+iBferJ5juR1FVhbHSbZtLsTtkPVegI9ug911WQ+KiCqErI
 VkiKUl8=
 =rNsn
 -----END PGP SIGNATURE-----

Merge tag 'v5.5-rc4' into locking/kcsan, to resolve conflicts

Conflicts:
	init/main.c
	lib/Kconfig.debug

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-12-30 08:10:51 +01:00
Mathieu Desnoyers 463f550fb4 rseq: Unregister rseq for clone CLONE_VM
It has been reported by Google that rseq is not behaving properly
with respect to clone when CLONE_VM is used without CLONE_THREAD.

It keeps the prior thread's rseq TLS registered when the TLS of the
thread has moved, so the kernel can corrupt the TLS of the parent.

The approach of clearing the per task-struct rseq registration
on clone with CLONE_THREAD flag is incomplete. It does not cover
the use-case of clone with CLONE_VM set, but without CLONE_THREAD.

Here is the rationale for unregistering rseq on clone with CLONE_VM
flag set:

1) CLONE_THREAD requires CLONE_SIGHAND, which requires CLONE_VM to be
   set. Therefore, just checking for CLONE_VM covers all CLONE_THREAD
   uses. There is no point in checking for both CLONE_THREAD and
   CLONE_VM,

2) There is the possibility of an unlikely scenario where CLONE_SETTLS
   is used without CLONE_VM. In order to be an issue, it would require
   that the rseq TLS is in a shared memory area.

   I do not plan on adding CLONE_SETTLS to the set of clone flags which
   unregister RSEQ, because it would require that we also unregister RSEQ
   on set_thread_area(2) and arch_prctl(2) ARCH_SET_FS for completeness.
   So rather than doing a partial solution, it appears better to let
   user-space explicitly perform rseq unregistration across clone if
   needed in scenarios where CLONE_VM is not set.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191211161713.4490-3-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-12-25 10:41:20 +01:00
Andrey Konovalov eec028c938 kcov: remote coverage support
Patch series " kcov: collect coverage from usb and vhost", v3.

This patchset extends kcov to allow collecting coverage from backgound
kernel threads.  This extension requires custom annotations for each of
the places where coverage collection is desired.  This patchset
implements this for hub events in the USB subsystem and for vhost
workers.  See the first patch description for details about the kcov
extension.  The other two patches apply this kcov extension to USB and
vhost.

Examples of other subsystems that might potentially benefit from this
when custom annotations are added (the list is based on
process_one_work() callers for bugs recently reported by syzbot):

1. fs: writeback wb_workfn() worker,
2. net: addrconf_dad_work()/addrconf_verify_work() workers,
3. net: neigh_periodic_work() worker,
4. net/p9: p9_write_work()/p9_read_work() workers,
5. block: blk_mq_run_work_fn() worker.

These patches have been used to enable coverage-guided USB fuzzing with
syzkaller for the last few years, see the details here:

  https://github.com/google/syzkaller/blob/master/docs/linux/external_fuzzing_usb.md

This patchset has been pushed to the public Linux kernel Gerrit
instance:

  https://linux-review.googlesource.com/c/linux/kernel/git/torvalds/linux/+/1524

This patch (of 3):

Add background thread coverage collection ability to kcov.

With KCOV_ENABLE coverage is collected only for syscalls that are issued
from the current process.  With KCOV_REMOTE_ENABLE it's possible to
collect coverage for arbitrary parts of the kernel code, provided that
those parts are annotated with kcov_remote_start()/kcov_remote_stop().

This allows to collect coverage from two types of kernel background
threads: the global ones, that are spawned during kernel boot in a
limited number of instances (e.g.  one USB hub_event() worker thread is
spawned per USB HCD); and the local ones, that are spawned when a user
interacts with some kernel interface (e.g.  vhost workers).

To enable collecting coverage from a global background thread, a unique
global handle must be assigned and passed to the corresponding
kcov_remote_start() call.  Then a userspace process can pass a list of
such handles to the KCOV_REMOTE_ENABLE ioctl in the handles array field
of the kcov_remote_arg struct.  This will attach the used kcov device to
the code sections, that are referenced by those handles.

Since there might be many local background threads spawned from
different userspace processes, we can't use a single global handle per
annotation.  Instead, the userspace process passes a non-zero handle
through the common_handle field of the kcov_remote_arg struct.  This
common handle gets saved to the kcov_handle field in the current
task_struct and needs to be passed to the newly spawned threads via
custom annotations.  Those threads should in turn be annotated with
kcov_remote_start()/kcov_remote_stop().

Internally kcov stores handles as u64 integers.  The top byte of a
handle is used to denote the id of a subsystem that this handle belongs
to, and the lower 4 bytes are used to denote the id of a thread instance
within that subsystem.  A reserved value 0 is used as a subsystem id for
common handles as they don't belong to a particular subsystem.  The
bytes 4-7 are currently reserved and must be zero.  In the future the
number of bytes used for the subsystem or handle ids might be increased.

When a particular userspace process collects coverage by via a common
handle, kcov will collect coverage for each code section that is
annotated to use the common handle obtained as kcov_handle from the
current task_struct.  However non common handles allow to collect
coverage selectively from different subsystems.

Link: http://lkml.kernel.org/r/e90e315426a384207edbec1d6aa89e43008e4caf.1572366574.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: David Windsor <dwindsor@gmail.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-04 19:44:14 -08:00
Linus Torvalds 043cf46825 Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Ingo Molnar:
 "The main changes in the timer code in this cycle were:

   - Clockevent updates:

      - timer-of framework cleanups. (Geert Uytterhoeven)

      - Use timer-of for the renesas-ostm and the device name to prevent
        name collision in case of multiple timers. (Geert Uytterhoeven)

      - Check if there is an error after calling of_clk_get in asm9260
        (Chuhong Yuan)

   - ABI fix: Zero out high order bits of nanoseconds on compat
     syscalls. This got broken a year ago, with apparently no side
     effects so far.

     Since the kernel would use random data otherwise I don't think we'd
     have other options but to fix the bug, even if there was a side
     effect to applications (Dmitry Safonov)

   - Optimize ns_to_timespec64() on 32-bit systems: move away from
     div_s64_rem() which can be slow, to div_u64_rem() which is faster
     (Arnd Bergmann)

   - Annotate KCSAN-reported false positive data races in
     hrtimer_is_queued() users by moving timer->state handling over to
     the READ_ONCE()/WRITE_ONCE() APIs. This documents these accesses
     (Eric Dumazet)

   - Misc cleanups and small fixes"

[ I undid the "ABI fix" and updated the comments instead. The reason
  there were apparently no side effects is that the fix was a no-op.

  The updated comment is to say _why_ it was a no-op.    - Linus ]

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  time: Zero the upper 32-bits in __kernel_timespec on 32-bit
  time: Rename tsk->real_start_time to ->start_boottime
  hrtimer: Remove the comment about not used HRTIMER_SOFTIRQ
  time: Fix spelling mistake in comment
  time: Optimize ns_to_timespec64()
  hrtimer: Annotate lockless access to timer->state
  clocksource/drivers/asm9260: Add a check for of_clk_get
  clocksource/drivers/renesas-ostm: Use unique device name instead of ostm
  clocksource/drivers/renesas-ostm: Convert to timer_of
  clocksource/drivers/timer-of: Use unique device name instead of timer
  clocksource/drivers/timer-of: Convert last full_name to %pOF
2019-12-03 12:20:25 -08:00
Linus Torvalds 168829ad09 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
 "The main changes in this cycle were:

   - A comprehensive rewrite of the robust/PI futex code's exit handling
     to fix various exit races. (Thomas Gleixner et al)

   - Rework the generic REFCOUNT_FULL implementation using
     atomic_fetch_* operations so that the performance impact of the
     cmpxchg() loops is mitigated for common refcount operations.

     With these performance improvements the generic implementation of
     refcount_t should be good enough for everybody - and this got
     confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and
     REFCOUNT_FULL entirely, leaving the generic implementation enabled
     unconditionally. (Will Deacon)

   - Other misc changes, fixes, cleanups"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
  lkdtm: Remove references to CONFIG_REFCOUNT_FULL
  locking/refcount: Remove unused 'refcount_error_report()' function
  locking/refcount: Consolidate implementations of refcount_t
  locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions
  locking/refcount: Move saturation warnings out of line
  locking/refcount: Improve performance of generic REFCOUNT_FULL code
  locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header
  locking/refcount: Remove unused refcount_*_checked() variants
  locking/refcount: Ensure integer operands are treated as signed
  locking/refcount: Define constants for saturation and max refcount values
  futex: Prevent exit livelock
  futex: Provide distinct return value when owner is exiting
  futex: Add mutex around futex exit
  futex: Provide state handling for exec() as well
  futex: Sanitize exit state handling
  futex: Mark the begin of futex exit explicitly
  futex: Set task::futex_state to DEAD right after handling futex exit
  futex: Split futex_mm_release() for exit/exec
  exit/exec: Seperate mm_release()
  futex: Replace PF_EXITPIDONE with a state
  ...
2019-11-26 16:02:40 -08:00
Linus Torvalds 77a05940ee Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The biggest changes in this cycle were:

   - Make kcpustat vtime aware (Frederic Weisbecker)

   - Rework the CFS load_balance() logic (Vincent Guittot)

   - Misc cleanups, smaller enhancements, fixes.

  The load-balancing rework is the most intrusive change: it replaces
  the old heuristics that have become less meaningful after the
  introduction of the PELT metrics, with a grounds-up load-balancing
  algorithm.

  As such it's not really an iterative series, but replaces the old
  load-balancing logic with the new one. We hope there are no
  performance regressions left - but statistically it's highly probable
  that there *is* going to be some workload that is hurting from these
  chnages. If so then we'd prefer to have a look at that workload and
  fix its scheduling, instead of reverting the changes"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits)
  rackmeter: Use vtime aware kcpustat accessor
  leds: Use all-in-one vtime aware kcpustat accessor
  cpufreq: Use vtime aware kcpustat accessors for user time
  procfs: Use all-in-one vtime aware kcpustat accessor
  sched/vtime: Bring up complete kcpustat accessor
  sched/cputime: Support other fields on kcpustat_field()
  sched/cpufreq: Move the cfs_rq_util_change() call to cpufreq_update_util()
  sched/fair: Add comments for group_type and balancing at SD_NUMA level
  sched/fair: Fix rework of find_idlest_group()
  sched/uclamp: Fix overzealous type replacement
  sched/Kconfig: Fix spelling mistake in user-visible help text
  sched/core: Further clarify sched_class::set_next_task()
  sched/fair: Use mul_u32_u32()
  sched/core: Simplify sched_class::pick_next_task()
  sched/core: Optimize pick_next_task()
  sched/core: Make pick_next_task_idle() more consistent
  sched/fair: Better document newidle_balance()
  leds: Use vtime aware kcpustat accessor to fetch CPUTIME_SYSTEM
  cpufreq: Use vtime aware kcpustat accessor to fetch CPUTIME_SYSTEM
  procfs: Use vtime aware kcpustat accessor to fetch CPUTIME_SYSTEM
  ...
2019-11-26 15:23:14 -08:00
Thomas Gleixner 3f186d9748 futex: Add mutex around futex exit
The mutex will be used in subsequent changes to replace the busy looping of
a waiter when the futex owner is currently executing the exit cleanup to
prevent a potential live lock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.845798895@linutronix.de
2019-11-20 09:40:10 +01:00
Thomas Gleixner 3d4775df0a futex: Replace PF_EXITPIDONE with a state
The futex exit handling relies on PF_ flags. That's suboptimal as it
requires a smp_mb() and an ugly lock/unlock of the exiting tasks pi_lock in
the middle of do_exit() to enforce the observability of PF_EXITING in the
futex code.

Add a futex_state member to task_struct and convert the PF_EXITPIDONE logic
over to the new state. The PF_EXITING dependency will be cleaned up in a
later step.

This prepares for handling various futex exit issues later.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.149449274@linutronix.de
2019-11-20 09:40:07 +01:00
Marco Elver dfd402a4c4 kcsan: Add Kernel Concurrency Sanitizer infrastructure
Kernel Concurrency Sanitizer (KCSAN) is a dynamic data-race detector for
kernel space. KCSAN is a sampling watchpoint-based data-race detector.
See the included Documentation/dev-tools/kcsan.rst for more details.

This patch adds basic infrastructure, but does not yet enable KCSAN for
any architecture.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-11-16 07:23:13 -08:00
Peter Zijlstra cf25e24db6 time: Rename tsk->real_start_time to ->start_boottime
Since it stores CLOCK_BOOTTIME, not, as the name suggests,
CLOCK_REALTIME, let's rename ->real_start_time to ->start_bootime.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-13 11:09:49 +01:00
Ingo Molnar 6d5a763c30 Linux 5.4-rc7
-----BEGIN PGP SIGNATURE-----
 
 iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAl3IqJQeHHRvcnZhbGRz
 QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGOiUH+gOEDwid5OODaFAd
 CggXugdFIlBZefKqGVNW5sjgX8pxFWHXuEMC8iNb6QXtQZdFrI6LFf9hhUDmzQtm
 6y1LPxxEiTZjObMEsBNylb7tyzgujFHcAlp0Zro3w/HLCqmYTSP3FF46i2u6KZfL
 XhkpM4X7R7qxlfpdhlfESv/ElRGocZe6SwXfC7pcPo5flFcmkdu9ijqhNd/6CZ/h
 Nf9rTsD/wEDVUelFbgVN+LJzlaB0tsyc4Zbof07n8OsFZjhdEOop8gfM/kTBLcyY
 6bh66SfDScdsNnC/l8csbPjSZRx+i+nQs67DyhGNnsSAFgHBZdC4Tb/2mDCwhCLR
 dUvuYZc=
 =1N6F
 -----END PGP SIGNATURE-----

Merge tag 'v5.4-rc7' into sched/core, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-11 08:34:59 +01:00
Jens Axboe 771b53d033 io-wq: small threadpool implementation for io_uring
This adds support for io-wq, a smaller and specialized thread pool
implementation. This is meant to replace workqueues for io_uring. Among
the reasons for this addition are:

- We can assign memory context smarter and more persistently if we
  manage the life time of threads.

- We can drop various work-arounds we have in io_uring, like the
  async_list.

- We can implement hashed work insertion, to manage concurrency of
  buffered writes without needing a) an extra workqueue, or b)
  needlessly making the concurrency of said workqueue very low
  which hurts performance of multiple buffered file writers.

- We can implement cancel through signals, for cancelling
  interruptible work like read/write (or send/recv) to/from sockets.

- We need the above cancel for being able to assign and use file tables
  from a process.

- We can implement a more thorough cancel operation in general.

- We need it to move towards a syslet/threadlet model for even faster
  async execution. For that we need to take ownership of the used
  threads.

This list is just off the top of my head. Performance should be the
same, or better, at least that's what I've seen in my testing. io-wq
supports basic NUMA functionality, setting up a pool per node.

io-wq hooks up to the scheduler schedule in/out just like workqueue
and uses that to drive the need for more/less workers.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-29 12:43:00 -06:00
Frederic Weisbecker e6d5bf3e32 sched/cputime: Add vtime guest task state
Record guest as a VTIME state instead of guessing it from VTIME_SYS and
PF_VCPU. This is going to simplify the cputime read side especially as
its state machine is going to further expand in order to fully support
kcpustat on nohz_full.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rjw@rjwysocki.net>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Link: https://lkml.kernel.org/r/20191016025700.31277-4-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29 10:01:11 +01:00
Frederic Weisbecker 14faf6fcac sched/cputime: Add vtime idle task state
Record idle as a VTIME state instead of guessing it from VTIME_SYS and
is_idle_task(). This is going to simplify the cputime read side
especially as its state machine is going to further expand in order to
fully support kcpustat on nohz_full.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rjw@rjwysocki.net>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Link: https://lkml.kernel.org/r/20191016025700.31277-3-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29 10:01:10 +01:00
Frederic Weisbecker 802f4a827f sched/vtime: Record CPU under seqcount for kcpustat needs
In order to compute the kcpustat delta on a nohz CPU, we'll need to
fetch the task running on that target. Checking that its vtime
state snapshot actually refers to the relevant target involves recording
that CPU under the seqcount locked on task switch.

This is a step toward making kcpustat moving forward on full nohz CPUs.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rjw@rjwysocki.net>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Link: https://lkml.kernel.org/r/20191016025700.31277-2-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29 10:01:08 +01:00
Julien Thierry 19c95f261c arm64: entry.S: Do not preempt from IRQ before all cpufeatures are enabled
Preempting from IRQ-return means that the task has its PSTATE saved
on the stack, which will get restored when the task is resumed and does
the actual IRQ return.

However, enabling some CPU features requires modifying the PSTATE. This
means that, if a task was scheduled out during an IRQ-return before all
CPU features are enabled, the task might restore a PSTATE that does not
include the feature enablement changes once scheduled back in.

* Task 1:

PAN == 0 ---|                          |---------------
            |                          |<- return from IRQ, PSTATE.PAN = 0
            | <- IRQ                   |
            +--------+ <- preempt()  +--
                                     ^
                                     |
                                     reschedule Task 1, PSTATE.PAN == 1
* Init:
        --------------------+------------------------
                            ^
                            |
                            enable_cpu_features
                            set PSTATE.PAN on all CPUs

Worse than this, since PSTATE is untouched when task switching is done,
a task missing the new bits in PSTATE might affect another task, if both
do direct calls to schedule() (outside of IRQ/exception contexts).

Fix this by preventing preemption on IRQ-return until features are
enabled on all CPUs.

This way the only PSTATE values that are saved on the stack are from
synchronous exceptions. These are expected to be fatal this early, the
exception is BRK for WARN_ON(), but as this uses do_debug_exception()
which keeps IRQs masked, it shouldn't call schedule().

Signed-off-by: Julien Thierry <julien.thierry@arm.com>
[james: Replaced a really cool hack, with an even simpler static key in C.
 expanded commit message with Julien's cover-letter ascii art]
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
2019-10-16 09:51:43 -07:00
Linus Torvalds 9c5efe9ae7 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:

 - Apply a number of membarrier related fixes and cleanups, which fixes
   a use-after-free race in the membarrier code

 - Introduce proper RCU protection for tasks on the runqueue - to get
   rid of the subtle task_rcu_dereference() interface that was easy to
   get wrong

 - Misc fixes, but also an EAS speedup

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Avoid redundant EAS calculation
  sched/core: Remove double update_max_interval() call on CPU startup
  sched/core: Fix preempt_schedule() interrupt return comment
  sched/fair: Fix -Wunused-but-set-variable warnings
  sched/core: Fix migration to invalid CPU in __set_cpus_allowed_ptr()
  sched/membarrier: Return -ENOMEM to userspace on memory allocation failure
  sched/membarrier: Skip IPIs when mm->mm_users == 1
  selftests, sched/membarrier: Add multi-threaded test
  sched/membarrier: Fix p->mm->membarrier_state racy load
  sched/membarrier: Call sync_core only before usermode for same mm
  sched/membarrier: Remove redundant check
  sched/membarrier: Fix private expedited registration check
  tasks, sched/core: RCUify the assignment of rq->curr
  tasks, sched/core: With a grace period after finish_task_switch(), remove unnecessary code
  tasks, sched/core: Ensure tasks are available for a grace period after leaving the runqueue
  tasks: Add a count of task RCU users
  sched/core: Convert vcpu_is_preempted() from macro to an inline function
  sched/fair: Remove unused cfs_rq_clock_task() function
2019-09-28 12:39:07 -07:00
Eric W. Biederman 3fbd7ee285 tasks: Add a count of task RCU users
Add a count of the number of RCU users (currently 1) of the task
struct so that we can later add the scheduler case and get rid of the
very subtle task_rcu_dereference(), and just use rcu_dereference().

As suggested by Oleg have the count overlap rcu_head so that no
additional space in task_struct is required.

Inspired-by: Linus Torvalds <torvalds@linux-foundation.org>
Inspired-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/87woebdplt.fsf_-_@x220.int.ebiederm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-25 17:42:29 +02:00
Linus Torvalds 84da111de0 hmm related patches for 5.4
This is more cleanup and consolidation of the hmm APIs and the very
 strongly related mmu_notifier interfaces. Many places across the tree
 using these interfaces are touched in the process. Beyond that a cleanup
 to the page walker API and a few memremap related changes round out the
 series:
 
 - General improvement of hmm_range_fault() and related APIs, more
   documentation, bug fixes from testing, API simplification &
   consolidation, and unused API removal
 
 - Simplify the hmm related kconfigs to HMM_MIRROR and DEVICE_PRIVATE, and
   make them internal kconfig selects
 
 - Hoist a lot of code related to mmu notifier attachment out of drivers by
   using a refcount get/put attachment idiom and remove the convoluted
   mmu_notifier_unregister_no_release() and related APIs.
 
 - General API improvement for the migrate_vma API and revision of its only
   user in nouveau
 
 - Annotate mmu_notifiers with lockdep and sleeping region debugging
 
 Two series unrelated to HMM or mmu_notifiers came along due to
 dependencies:
 
 - Allow pagemap's memremap_pages family of APIs to work without providing
   a struct device
 
 - Make walk_page_range() and related use a constant structure for function
   pointers
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCgAdFiEEfB7FMLh+8QxL+6i3OG33FX4gmxoFAl1/nnkACgkQOG33FX4g
 mxqaRg//c6FqowV1pQlLutvAOAgMdpzfZ9eaaDKngy9RVQxz+k/MmJrdRH/p/mMA
 Pq93A1XfwtraGKErHegFXGEDk4XhOustVAVFwvjyXO41dTUdoFVUkti6ftbrl/rS
 6CT+X90jlvrwdRY7QBeuo7lxx7z8Qkqbk1O1kc1IOracjKfNJS+y6LTamy6weM3g
 tIMHI65PkxpRzN36DV9uCN5dMwFzJ73DWHp1b0acnDIigkl6u5zp6orAJVWRjyQX
 nmEd3/IOvdxaubAoAvboNS5CyVb4yS9xshWWMbH6AulKJv3Glca1Aa7QuSpBoN8v
 wy4c9+umzqRgzgUJUe1xwN9P49oBNhJpgBSu8MUlgBA4IOc3rDl/Tw0b5KCFVfkH
 yHkp8n6MP8VsRrzXTC6Kx0vdjIkAO8SUeylVJczAcVSyHIo6/JUJCVDeFLSTVymh
 EGWJ7zX2iRhUbssJ6/izQTTQyCH3YIyZ5QtqByWuX2U7ZrfkqS3/EnBW1Q+j+gPF
 Z2yW8iT6k0iENw6s8psE9czexuywa/Lttz94IyNlOQ8rJTiQqB9wLaAvg9hvUk7a
 kuspL+JGIZkrL3ouCeO/VA6xnaP+Q7nR8geWBRb8zKGHmtWrb5Gwmt6t+vTnCC2l
 olIDebrnnxwfBQhEJ5219W+M1pBpjiTpqK/UdBd92A4+sOOhOD0=
 =FRGg
 -----END PGP SIGNATURE-----

Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

Pull hmm updates from Jason Gunthorpe:
 "This is more cleanup and consolidation of the hmm APIs and the very
  strongly related mmu_notifier interfaces. Many places across the tree
  using these interfaces are touched in the process. Beyond that a
  cleanup to the page walker API and a few memremap related changes
  round out the series:

   - General improvement of hmm_range_fault() and related APIs, more
     documentation, bug fixes from testing, API simplification &
     consolidation, and unused API removal

   - Simplify the hmm related kconfigs to HMM_MIRROR and DEVICE_PRIVATE,
     and make them internal kconfig selects

   - Hoist a lot of code related to mmu notifier attachment out of
     drivers by using a refcount get/put attachment idiom and remove the
     convoluted mmu_notifier_unregister_no_release() and related APIs.

   - General API improvement for the migrate_vma API and revision of its
     only user in nouveau

   - Annotate mmu_notifiers with lockdep and sleeping region debugging

  Two series unrelated to HMM or mmu_notifiers came along due to
  dependencies:

   - Allow pagemap's memremap_pages family of APIs to work without
     providing a struct device

   - Make walk_page_range() and related use a constant structure for
     function pointers"

* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (75 commits)
  libnvdimm: Enable unit test infrastructure compile checks
  mm, notifier: Catch sleeping/blocking for !blockable
  kernel.h: Add non_block_start/end()
  drm/radeon: guard against calling an unpaired radeon_mn_unregister()
  csky: add missing brackets in a macro for tlb.h
  pagewalk: use lockdep_assert_held for locking validation
  pagewalk: separate function pointers from iterator data
  mm: split out a new pagewalk.h header from mm.h
  mm/mmu_notifiers: annotate with might_sleep()
  mm/mmu_notifiers: prime lockdep
  mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end
  mm/mmu_notifiers: remove the __mmu_notifier_invalidate_range_start/end exports
  mm/hmm: hmm_range_fault() infinite loop
  mm/hmm: hmm_range_fault() NULL pointer bug
  mm/hmm: fix hmm_range_fault()'s handling of swapped out pages
  mm/mmu_notifiers: remove unregister_no_release
  RDMA/odp: remove ib_ucontext from ib_umem
  RDMA/odp: use mmu_notifier_get/put for 'struct ib_ucontext_per_mm'
  RDMA/mlx5: Use odp instead of mr->umem in pagefault_mr
  RDMA/mlx5: Use ib_umem_start instead of umem.address
  ...
2019-09-21 10:07:42 -07:00
Qian Cai 42fd8baab3 sched/core: Convert vcpu_is_preempted() from macro to an inline function
Clang reports this warning:

  kernel/locking/osq_lock.c:25:19: warning: unused function 'node_cpu' [-Wunused-function]

due to osq_lock() calling vcpu_is_preempted(node_cpu(node->prev))), but
vcpu_is_preempted() is compiled away. Fix it by converting the dummy
vcpu_is_preempted() from a macro to a proper static inline function.

Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: juri.lelli@redhat.com
Cc: rostedt@goodmis.org
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/1568730894-10483-1-git-send-email-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-18 12:38:17 +02:00
Linus Torvalds 7f2444d38f Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core timer updates from Thomas Gleixner:
 "Timers and timekeeping updates:

   - A large overhaul of the posix CPU timer code which is a preparation
     for moving the CPU timer expiry out into task work so it can be
     properly accounted on the task/process.

     An update to the bogus permission checks will come later during the
     merge window as feedback was not complete before heading of for
     travel.

   - Switch the timerqueue code to use cached rbtrees and get rid of the
     homebrewn caching of the leftmost node.

   - Consolidate hrtimer_init() + hrtimer_init_sleeper() calls into a
     single function

   - Implement the separation of hrtimers to be forced to expire in hard
     interrupt context even when PREEMPT_RT is enabled and mark the
     affected timers accordingly.

   - Implement a mechanism for hrtimers and the timer wheel to protect
     RT against priority inversion and live lock issues when a (hr)timer
     which should be canceled is currently executing the callback.
     Instead of infinitely spinning, the task which tries to cancel the
     timer blocks on a per cpu base expiry lock which is held and
     released by the (hr)timer expiry code.

   - Enable the Hyper-V TSC page based sched_clock for Hyper-V guests
     resulting in faster access to timekeeping functions.

   - Updates to various clocksource/clockevent drivers and their device
     tree bindings.

   - The usual small improvements all over the place"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (101 commits)
  posix-cpu-timers: Fix permission check regression
  posix-cpu-timers: Always clear head pointer on dequeue
  hrtimer: Add a missing bracket and hide `migration_base' on !SMP
  posix-cpu-timers: Make expiry_active check actually work correctly
  posix-timers: Unbreak CONFIG_POSIX_TIMERS=n build
  tick: Mark sched_timer to expire in hard interrupt context
  hrtimer: Add kernel doc annotation for HRTIMER_MODE_HARD
  x86/hyperv: Hide pv_ops access for CONFIG_PARAVIRT=n
  posix-cpu-timers: Utilize timerqueue for storage
  posix-cpu-timers: Move state tracking to struct posix_cputimers
  posix-cpu-timers: Deduplicate rlimit handling
  posix-cpu-timers: Remove pointless comparisons
  posix-cpu-timers: Get rid of 64bit divisions
  posix-cpu-timers: Consolidate timer expiry further
  posix-cpu-timers: Get rid of zero checks
  rlimit: Rewrite non-sensical RLIMIT_CPU comment
  posix-cpu-timers: Respect INFINITY for hard RTTIME limit
  posix-cpu-timers: Switch thread group sampling to array
  posix-cpu-timers: Restructure expiry array
  posix-cpu-timers: Remove cputime_expires
  ...
2019-09-17 12:35:15 -07:00
Ingo Molnar 563c4f85f9 Merge branch 'sched/rt' into sched/core, to pick up -rt changes
Pick up the first couple of patches working towards PREEMPT_RT.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-16 14:05:04 +02:00
Daniel Vetter 312364f353 kernel.h: Add non_block_start/end()
In some special cases we must not block, but there's not a spinlock,
preempt-off, irqs-off or similar critical section already that arms the
might_sleep() debug checks. Add a non_block_start/end() pair to annotate
these.

This will be used in the oom paths of mmu-notifiers, where blocking is not
allowed to make sure there's forward progress. Quoting Michal:

"The notifier is called from quite a restricted context - oom_reaper -
which shouldn't depend on any locks or sleepable conditionals. The code
should be swift as well but we mostly do care about it to make a forward
progress. Checking for sleepable context is the best thing we could come
up with that would describe these demands at least partially."

Peter also asked whether we want to catch spinlocks on top, but Michal
said those are less of a problem because spinlocks can't have an indirect
dependency upon the page allocator and hence close the loop with the oom
reaper.

Suggested by Michal Hocko.

Link: https://lore.kernel.org/r/20190826201425.17547-4-daniel.vetter@ffwll.ch
Acked-by: Christian König <christian.koenig@amd.com> (v1)
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
2019-09-07 04:28:05 -03:00
Thomas Gleixner 3a245c0f11 posix-cpu-timers: Move expiry cache into struct posix_cputimers
The expiry cache belongs into the posix_cputimers container where the other
cpu timers information is.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190821192921.014444012@linutronix.de
2019-08-28 11:50:35 +02:00
Thomas Gleixner 9eacb5c7e6 sched: Move struct task_cputime to types.h
For upcoming posix-timer changes to avoid include recursion hell.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190821192920.909530418@linutronix.de
2019-08-28 11:50:34 +02:00
Thomas Gleixner 2b69942f90 posix-cpu-timers: Create a container struct
Per task/process data of posix CPU timers is all over the place which
makes the code hard to follow and requires ifdeffery.

Create a container to hold all this information in one place, so data is
consolidated and the ifdeffery can be confined to the posix timer header
file and removed from places like fork.

As a first step, move the cpu_timers list head array into the new struct
and clean up the initializers and simplify fork. The remaining #ifdef in
fork will be removed later.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/20190821192920.819418976@linutronix.de
2019-08-28 11:50:33 +02:00
Thomas Gleixner c1a280b68d sched/preempt: Use CONFIG_PREEMPTION where appropriate
CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by
CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same
functionality which today depends on CONFIG_PREEMPT.

Switch the preemption code, scheduler and init task over to use
CONFIG_PREEMPTION.

That's the first step towards RT in that area. The more complex changes are
coming separately.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20190726212124.117528401@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-07-31 19:03:34 +02:00
Mathieu Poirier f9a25f776d cpusets: Rebuild root domain deadline accounting information
When the topology of root domains is modified by CPUset or CPUhotplug
operations information about the current deadline bandwidth held in the
root domain is lost.

This patch addresses the issue by recalculating the lost deadline
bandwidth information by circling through the deadline tasks held in
CPUsets and adding their current load to the root domain they are
associated with.

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
[ Various additional modifications. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: rostedt@goodmis.org
Cc: tj@kernel.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-4-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-07-25 15:55:01 +02:00
Jann Horn cb361d8cde sched/fair: Use RCU accessors consistently for ->numa_group
The old code used RCU annotations and accessors inconsistently for
->numa_group, which can lead to use-after-frees and NULL dereferences.

Let all accesses to ->numa_group use proper RCU helpers to prevent such
issues.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Fixes: 8c8a743c50 ("sched/numa: Use {cpu, pid} to create task groups for shared faults")
Link: https://lkml.kernel.org/r/20190716152047.14424-3-jannh@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-07-25 15:37:05 +02:00
Linus Torvalds c236b6dd48 request_key improvements
-----BEGIN PGP SIGNATURE-----
 
 iQIVAwUAXRPObfu3V2unywtrAQJLKA//WENO5pZDHe49T+4GCY0ZmnGHKBUnU7g9
 DUjxSNS8a/nwCyEdApZk9uHp2xsOedP6pjQ4VRWMQfrIPx0Yh9o3J+BQxvyP7PDf
 jEH+5CYC8dZnJJjjteWCcPEGrUoNb1YKfDRBU745YY+rLdHWvhHc27B6SYBg5BGT
 OwW3qyHvp0WMp7TehMALdnkqGph5gR5QMr45tOrH6DkGAhN8mAIKD699d3MqZG73
 +S5KlQOlDlEVrxbD/BgzlzEJQUBQyq8hd61taBFT7LXBNlLJJOnMhd7UJY5IJE7J
 Vi9NpcLj4Emwv4wvZ2xneV0rMbsCbxRMKZLDRuqQ6Tm17xjpjro4n1ujneTAqmmy
 d+XlrVQ2ZMciMNmGleezOoBib9QbY5NWdilc2ls5ydFGiBVL73bIOYtEQNai8lWd
 LBBIIrxOmLO7bnipgqVKRnqeMdMkpWaLISoRfSeJbRt4lGxmka9bDBrSgONnxzJK
 JG+sB8ahSVZaBbhERW8DKnBz61Yf8ka7ijVvjH3zCXu0rbLTy+LLUz5kbzbBP9Fc
 LiUapLV/v420gD2ZRCgPQwtQui4TpBkSGJKS1Ippyn7LGBNCZLM4Y8vOoo4nqr7z
 RhpEKbKeOdVjORaYjO8Zttj8gN9rT6WnPcyCTHdNEnyjotU1ykyVBkzexj+VYvjM
 C3eIdjG7Jk0=
 =c2FO
 -----END PGP SIGNATURE-----

Merge tag 'keys-request-20190626' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull request_key improvements from David Howells:
 "These are all request_key()-related, including a fix and some improvements:

   - Fix the lack of a Link permission check on a key found by
     request_key(), thereby enabling request_key() to link keys that
     don't grant this permission to the target keyring (which must still
     grant Write permission).

     Note that the key must be in the caller's keyrings already to be
     found.

   - Invalidate used request_key authentication keys rather than
     revoking them, so that they get cleaned up immediately rather than
     hanging around till the expiry time is passed.

   - Move the RCU locks outwards from the keyring search functions so
     that a request_key_rcu() can be provided. This can be called in RCU
     mode, so it can't sleep and can't upcall - but it can be called
     from LOOKUP_RCU pathwalk mode.

   - Cache the latest positive result of request_key*() temporarily in
     task_struct so that filesystems that make a lot of request_key()
     calls during pathwalk can take advantage of it to avoid having to
     redo the searching. This requires CONFIG_KEYS_REQUEST_CACHE=y.

     It is assumed that the key just found is likely to be used multiple
     times in each step in an RCU pathwalk, and is likely to be reused
     for the next step too.

     Note that the cleanup of the cache is done on TIF_NOTIFY_RESUME,
     just before userspace resumes, and on exit"

* tag 'keys-request-20190626' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  keys: Kill off request_key_async{,_with_auxdata}
  keys: Cache result of request_key*() temporarily in task_struct
  keys: Provide request_key_rcu()
  keys: Move the RCU locks outwards from the keyring search functions
  keys: Invalidate used request_key authentication keys
  keys: Fix request_key() lack of Link perm check on found key
2019-07-08 19:19:37 -07:00
Linus Torvalds dad1c12ed8 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:

 - Remove the unused per rq load array and all its infrastructure, by
   Dietmar Eggemann.

 - Add utilization clamping support by Patrick Bellasi. This is a
   refinement of the energy aware scheduling framework with support for
   boosting of interactive and capping of background workloads: to make
   sure critical GUI threads get maximum frequency ASAP, and to make
   sure background processing doesn't unnecessarily move to cpufreq
   governor to higher frequencies and less energy efficient CPU modes.

 - Add the bare minimum of tracepoints required for LISA EAS regression
   testing, by Qais Yousef - which allows automated testing of various
   power management features, including energy aware scheduling.

 - Restructure the former tsk_nr_cpus_allowed() facility that the -rt
   kernel used to modify the scheduler's CPU affinity logic such as
   migrate_disable() - introduce the task->cpus_ptr value instead of
   taking the address of &task->cpus_allowed directly - by Sebastian
   Andrzej Siewior.

 - Misc optimizations, fixes, cleanups and small enhancements - see the
   Git log for details.

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  sched/uclamp: Add uclamp support to energy_compute()
  sched/uclamp: Add uclamp_util_with()
  sched/cpufreq, sched/uclamp: Add clamps for FAIR and RT tasks
  sched/uclamp: Set default clamps for RT tasks
  sched/uclamp: Reset uclamp values on RESET_ON_FORK
  sched/uclamp: Extend sched_setattr() to support utilization clamping
  sched/core: Allow sched_setattr() to use the current policy
  sched/uclamp: Add system default clamps
  sched/uclamp: Enforce last task's UCLAMP_MAX
  sched/uclamp: Add bucket local max tracking
  sched/uclamp: Add CPU's clamp buckets refcounting
  sched/fair: Rename weighted_cpuload() to cpu_runnable_load()
  sched/debug: Export the newly added tracepoints
  sched/debug: Add sched_overutilized tracepoint
  sched/debug: Add new tracepoint to track PELT at se level
  sched/debug: Add new tracepoints to track PELT at rq level
  sched/debug: Add a new sched_trace_*() helper functions
  sched/autogroup: Make autogroup_path() always available
  sched/wait: Deduplicate code with do-while
  sched/topology: Remove unused 'sd' parameter from arch_scale_cpu_capacity()
  ...
2019-07-08 16:39:53 -07:00
Linus Torvalds 46f1ec23a4 Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:
 "The changes in this cycle are:

   - RCU flavor consolidation cleanups and optmizations

   - Documentation updates

   - Miscellaneous fixes

   - SRCU updates

   - RCU-sync flavor consolidation

   - Torture-test updates

   - Linux-kernel memory-consistency-model updates, most notably the
     addition of plain C-language accesses"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (61 commits)
  tools/memory-model: Improve data-race detection
  tools/memory-model: Change definition of rcu-fence
  tools/memory-model: Expand definition of barrier
  tools/memory-model: Do not use "herd" to refer to "herd7"
  tools/memory-model: Fix comment in MP+poonceonces.litmus
  Documentation: atomic_t.txt: Explain ordering provided by smp_mb__{before,after}_atomic()
  rcu: Don't return a value from rcu_assign_pointer()
  rcu: Force inlining of rcu_read_lock()
  rcu: Fix irritating whitespace error in rcu_assign_pointer()
  rcu: Upgrade sync_exp_work_done() to smp_mb()
  rcutorture: Upper case solves the case of the vanishing NULL pointer
  torture: Suppress propagating trace_printk() warning
  rcutorture: Dump trace buffer for callback pipe drain failures
  torture: Add --trust-make to suppress "make clean"
  torture: Make --cpus override idleness calculations
  torture: Run kernel build in source directory
  torture: Add function graph-tracing cheat sheet
  torture: Capture qemu output
  rcutorture: Tweak kvm options
  rcutorture: Add trivial RCU implementation
  ...
2019-07-08 15:45:14 -07:00
Patrick Bellasi a509a7cd79 sched/uclamp: Extend sched_setattr() to support utilization clamping
The SCHED_DEADLINE scheduling class provides an advanced and formal
model to define tasks requirements that can translate into proper
decisions for both task placements and frequencies selections. Other
classes have a more simplified model based on the POSIX concept of
priorities.

Such a simple priority based model however does not allow to exploit
most advanced features of the Linux scheduler like, for example, driving
frequencies selection via the schedutil cpufreq governor. However, also
for non SCHED_DEADLINE tasks, it's still interesting to define tasks
properties to support scheduler decisions.

Utilization clamping exposes to user-space a new set of per-task
attributes the scheduler can use as hints about the expected/required
utilization for a task. This allows to implement a "proactive" per-task
frequency control policy, a more advanced policy than the current one
based just on "passive" measured task utilization. For example, it's
possible to boost interactive tasks (e.g. to get better performance) or
cap background tasks (e.g. to be more energy/thermal efficient).

Introduce a new API to set utilization clamping values for a specified
task by extending sched_setattr(), a syscall which already allows to
define task specific properties for different scheduling classes. A new
pair of attributes allows to specify a minimum and maximum utilization
the scheduler can consider for a task.

Do that by validating the required clamp values before and then applying
the required changes using _the_ same pattern already in use for
__setscheduler(). This ensures that the task is re-enqueued with the new
clamp values.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-7-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-24 19:23:46 +02:00
Patrick Bellasi e8f14172c6 sched/uclamp: Add system default clamps
Tasks without a user-defined clamp value are considered not clamped
and by default their utilization can have any value in the
[0..SCHED_CAPACITY_SCALE] range.

Tasks with a user-defined clamp value are allowed to request any value
in that range, and the required clamp is unconditionally enforced.
However, a "System Management Software" could be interested in limiting
the range of clamp values allowed for all tasks.

Add a privileged interface to define a system default configuration via:

  /proc/sys/kernel/sched_uclamp_util_{min,max}

which works as an unconditional clamp range restriction for all tasks.

With the default configuration, the full SCHED_CAPACITY_SCALE range of
values is allowed for each clamp index. Otherwise, the task-specific
clamp is capped by the corresponding system default value.

Do that by tracking, for each task, the "effective" clamp value and
bucket the task has been refcounted in at enqueue time. This
allows to lazy aggregate "requested" and "system default" values at
enqueue time and simplifies refcounting updates at dequeue time.

The cached bucket ids are used to avoid (relatively) more expensive
integer divisions every time a task is enqueued.

An active flag is used to report when the "effective" value is valid and
thus the task is actually refcounted in the corresponding rq's bucket.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-5-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-24 19:23:45 +02:00
Patrick Bellasi 69842cba9a sched/uclamp: Add CPU's clamp buckets refcounting
Utilization clamping allows to clamp the CPU's utilization within a
[util_min, util_max] range, depending on the set of RUNNABLE tasks on
that CPU. Each task references two "clamp buckets" defining its minimum
and maximum (util_{min,max}) utilization "clamp values". A CPU's clamp
bucket is active if there is at least one RUNNABLE tasks enqueued on
that CPU and refcounting that bucket.

When a task is {en,de}queued {on,from} a rq, the set of active clamp
buckets on that CPU can change. If the set of active clamp buckets
changes for a CPU a new "aggregated" clamp value is computed for that
CPU. This is because each clamp bucket enforces a different utilization
clamp value.

Clamp values are always MAX aggregated for both util_min and util_max.
This ensures that no task can affect the performance of other
co-scheduled tasks which are more boosted (i.e. with higher util_min
clamp) or less capped (i.e. with higher util_max clamp).

A task has:
   task_struct::uclamp[clamp_id]::bucket_id
to track the "bucket index" of the CPU's clamp bucket it refcounts while
enqueued, for each clamp index (clamp_id).

A runqueue has:
   rq::uclamp[clamp_id]::bucket[bucket_id].tasks
to track how many RUNNABLE tasks on that CPU refcount each
clamp bucket (bucket_id) of a clamp index (clamp_id).
It also has a:
   rq::uclamp[clamp_id]::bucket[bucket_id].value
to track the clamp value of each clamp bucket (bucket_id) of a clamp
index (clamp_id).

The rq::uclamp::bucket[clamp_id][] array is scanned every time it's
needed to find a new MAX aggregated clamp value for a clamp_id. This
operation is required only when it's dequeued the last task of a clamp
bucket tracking the current MAX aggregated clamp value. In this case,
the CPU is either entering IDLE or going to schedule a less boosted or
more clamped task.
The expected number of different clamp values configured at build time
is small enough to fit the full unordered array into a single cache
line, for configurations of up to 7 buckets.

Add to struct rq the basic data structures required to refcount the
number of RUNNABLE tasks for each clamp bucket. Add also the max
aggregation required to update the rq's clamp value at each
enqueue/dequeue event.

Use a simple linear mapping of clamp values into clamp buckets.
Pre-compute and cache bucket_id to avoid integer divisions at
enqueue/dequeue time.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-24 19:23:44 +02:00
Qais Yousef 3c93a0c04d sched/debug: Add a new sched_trace_*() helper functions
The new functions allow modules to access internal data structures of
unexported struct cfs_rq and struct rq to extract important information
from the tracepoints to be introduced in later patches.

While at it fix alphabetical order of struct declarations in sched.h

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>
Link: https://lkml.kernel.org/r/20190604111459.2862-3-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-24 19:23:41 +02:00
David Howells 7743c48e54 keys: Cache result of request_key*() temporarily in task_struct
If a filesystem uses keys to hold authentication tokens, then it needs a
token for each VFS operation that might perform an authentication check -
either by passing it to the server, or using to perform a check based on
authentication data cached locally.

For open files this isn't a problem, since the key should be cached in the
file struct since it represents the subject performing operations on that
file descriptor.

During pathwalk, however, there isn't anywhere to cache the key, except
perhaps in the nameidata struct - but that isn't exposed to the
filesystems.  Further, a pathwalk can incur a lot of operations, calling
one or more of the following, for instance:

	->lookup()
	->permission()
	->d_revalidate()
	->d_automount()
	->get_acl()
	->getxattr()

on each dentry/inode it encounters - and each one may need to call
request_key().  And then, at the end of pathwalk, it will call the actual
operation:

	->mkdir()
	->mknod()
	->getattr()
	->open()
	...

which may need to go and get the token again.

However, it is very likely that all of the operations on a single
dentry/inode - and quite possibly a sequence of them - will all want to use
the same authentication token, which suggests that caching it would be a
good idea.

To this end:

 (1) Make it so that a positive result of request_key() and co. that didn't
     require upcalling to userspace is cached temporarily in task_struct.

 (2) The cache is 1 deep, so a new result displaces the old one.

 (3) The key is released by exit and by notify-resume.

 (4) The cache is cleared in a newly forked process.

Signed-off-by: David Howells <dhowells@redhat.com>
2019-06-19 16:10:15 +01:00
Heiko Carstens 4ecf0a43e7 processor: get rid of cpu_relax_yield
stop_machine is the only user left of cpu_relax_yield. Given that it
now has special semantics which are tied to stop_machine introduce a
weak stop_machine_yield function which architectures can override, and
get rid of the generic cpu_relax_yield implementation.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2019-06-15 12:25:55 +02:00
Martin Schwidefsky 38f2c691a4 s390: improve wait logic of stop_machine
The stop_machine loop to advance the state machine and to wait for all
affected CPUs to check-in calls cpu_relax_yield in a tight loop until
the last missing CPUs acknowledged the state transition.

On a virtual system where not all logical CPUs are backed by real CPUs
all the time it can take a while for all CPUs to check-in. With the
current definition of cpu_relax_yield a diagnose 0x44 is done which
tells the hypervisor to schedule *some* other CPU. That can be any
CPU and not necessarily one of the CPUs that need to run in order to
advance the state machine. This can lead to a pretty bad diagnose 0x44
storm until the last missing CPU finally checked-in.

Replace the undirected cpu_relax_yield based on diagnose 0x44 with a
directed yield. Each CPU in the wait loop will pick up the next CPU
in the cpumask of stop_machine. The diagnose 0x9c is used to tell the
hypervisor to run this next CPU instead of the current one. If there
is only a limited number of real CPUs backing the virtual CPUs we
end up with the real CPUs passed around in a round-robin fashion.

[heiko.carstens@de.ibm.com]:
    Use cpumask_next_wrap as suggested by Peter Zijlstra.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2019-06-15 12:25:52 +02:00
Sebastian Andrzej Siewior 3bd3706251 sched/core: Provide a pointer to the valid CPU mask
In commit:

  4b53a3412d ("sched/core: Remove the tsk_nr_cpus_allowed() wrapper")

the tsk_nr_cpus_allowed() wrapper was removed. There was not
much difference in !RT but in RT we used this to implement
migrate_disable(). Within a migrate_disable() section the CPU mask is
restricted to single CPU while the "normal" CPU mask remains untouched.

As an alternative implementation Ingo suggested to use:

	struct task_struct {
		const cpumask_t		*cpus_ptr;
		cpumask_t		cpus_mask;
        };
with
	t->cpus_ptr = &t->cpus_mask;

In -RT we then can switch the cpus_ptr to:

	t->cpus_ptr = &cpumask_of(task_cpu(p));

in a migration disabled region. The rules are simple:

 - Code that 'uses' ->cpus_allowed would use the pointer.
 - Code that 'modifies' ->cpus_allowed would use the direct mask.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190423142636.14347-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-03 11:49:37 +02:00
Paul E. McKenney 23634ebc1d rcu: Check for wakeup-safe conditions in rcu_read_unlock_special()
When RCU core processing is offloaded from RCU_SOFTIRQ to the rcuc
kthreads, a full and unconditional wakeup is required to initiate RCU
core processing.  In contrast, when RCU core processing is carried
out by RCU_SOFTIRQ, a raise_softirq() suffices.  Of course, there are
situations where raise_softirq() does a full wakeup, but these do not
occur with normal usage of rcu_read_unlock().

The reason that full wakeups can be problematic is that the scheduler
sometimes invokes rcu_read_unlock() with its pi or rq locks held,
which can of course result in deadlock in CONFIG_PREEMPT=y kernels when
rcu_read_unlock() invokes the scheduler.  Scheduler invocations can happen
in the following situations: (1) The just-ended reader has been subjected
to RCU priority boosting, in which case rcu_read_unlock() must deboost,
(2) Interrupts were disabled across the call to rcu_read_unlock(), so
the quiescent state must be deferred, requiring a wakeup of the rcuc
kthread corresponding to the current CPU.

Now, the scheduler may hold one of its locks across rcu_read_unlock()
only if preemption has been disabled across the entire RCU read-side
critical section, which in the days prior to RCU flavor consolidation
meant that rcu_read_unlock() never needed to do wakeups.  However, this
is no longer the case for any but the first rcu_read_unlock() following a
condition (e.g., preempted RCU reader) requiring special rcu_read_unlock()
attention.  For example, an RCU read-side critical section might be
preempted, but preemption might be disabled across the rcu_read_unlock().
The rcu_read_unlock() must defer the quiescent state, and therefore
leaves the task queued on its leaf rcu_node structure.  If a scheduler
interrupt occurs, the scheduler might well invoke rcu_read_unlock() with
one of its locks held.  However, the preempted task is still queued, so
rcu_read_unlock() will attempt to defer the quiescent state once more.
When RCU core processing is carried out by RCU_SOFTIRQ, this works just
fine: The raise_softirq() function simply sets a bit in a per-CPU mask
and the RCU core processing will be undertaken upon return from interrupt.

Not so when RCU core processing is carried out by the rcuc kthread: In this
case, the required wakeup can result in deadlock.

The initial solution to this problem was to use set_tsk_need_resched() and
set_preempt_need_resched() to force a future context switch, which allows
rcu_preempt_note_context_switch() to report the deferred quiescent state
to RCU's core processing.  Unfortunately for expedited grace periods,
there can be a significant delay between the call for a context switch
and the actual context switch.

This commit therefore introduces a ->deferred_qs flag to the task_struct
structure's rcu_special structure.  This flag is initially false, and
is set to true by the first call to rcu_read_unlock() requiring special
attention, then finally reset back to false when the quiescent state is
finally reported.  Then rcu_read_unlock() attempts full wakeups only when
->deferred_qs is false, that is, on the first rcu_read_unlock() requiring
special attention.  Note that a chain of RCU readers linked by some other
sort of reader may find that a later rcu_read_unlock() is once again able
to do a full wakeup, courtesy of an intervening preemption:

	rcu_read_lock();
	/* preempted */
	local_irq_disable();
	rcu_read_unlock(); /* Can do full wakeup, sets ->deferred_qs. */
	rcu_read_lock();
	local_irq_enable();
	preempt_disable()
	rcu_read_unlock(); /* Cannot do full wakeup, ->deferred_qs set. */
	rcu_read_lock();
	preempt_enable();
	/* preempted, >deferred_qs reset. */
	local_irq_disable();
	rcu_read_unlock(); /* Can again do full wakeup, sets ->deferred_qs. */

Such linked RCU readers do not yet seem to appear in the Linux kernel, and
it is probably best if they don't.  However, RCU needs to handle them, and
some variations on this theme could make even raise_softirq() unsafe due to
the possibility of its doing a full wakeup.  This commit therefore also
avoids invoking raise_softirq() when the ->deferred_qs set flag is set.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
2019-05-25 14:50:47 -07:00
Suren Baghdasaryan 8af0c18af1 include/: refactor headers to allow kthread.h inclusion in psi_types.h
kthread.h can't be included in psi_types.h because it creates a circular
inclusion with kthread.h eventually including psi_types.h and
complaining on kthread structures not being defined because they are
defined further in the kthread.h.  Resolve this by removing psi_types.h
inclusion from the headers included from kthread.h.

Link: http://lkml.kernel.org/r/20190319235619.260832-7-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 19:52:48 -07:00
Linus Torvalds abde77eb5c Merge branch 'for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
 "This includes Roman's cgroup2 freezer implementation.

  It's a separate machanism from cgroup1 freezer. Instead of blocking
  user tasks in arbitrary uninterruptible sleeps, the new implementation
  extends jobctl stop - frozen tasks are trapped in jobctl stop until
  thawed and can be killed and ptraced. Lots of thanks to Oleg for
  sheperding the effort.

  Other than that, there are a few trivial changes"

* 'for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: never call do_group_exit() with task->frozen bit set
  kernel: cgroup: fix misuse of %x
  cgroup: get rid of cgroup_freezer_frozen_exit()
  cgroup: prevent spurious transition into non-frozen state
  cgroup: Remove unused cgrp variable
  cgroup: document cgroup v2 freezer interface
  cgroup: add tracing points for cgroup v2 freezer
  cgroup: make TRACE_CGROUP_PATH irq-safe
  kselftests: cgroup: add freezer controller self-tests
  kselftests: cgroup: don't fail on cg_kill_all() error in cg_destroy()
  cgroup: cgroup v2 freezer
  cgroup: protect cgroup->nr_(dying_)descendants by css_set_lock
  cgroup: implement __cgroup_task_count() helper
  cgroup: rename freezer.c into legacy_freezer.c
  cgroup: remove extra cgroup_migrate_finish() call
2019-05-09 13:52:12 -07:00
Roman Gushchin 76f969e894 cgroup: cgroup v2 freezer
Cgroup v1 implements the freezer controller, which provides an ability
to stop the workload in a cgroup and temporarily free up some
resources (cpu, io, network bandwidth and, potentially, memory)
for some other tasks. Cgroup v2 lacks this functionality.

This patch implements freezer for cgroup v2.

Cgroup v2 freezer tries to put tasks into a state similar to jobctl
stop. This means that tasks can be killed, ptraced (using
PTRACE_SEIZE*), and interrupted. It is possible to attach to
a frozen task, get some information (e.g. read registers) and detach.
It's also possible to migrate a frozen tasks to another cgroup.

This differs cgroup v2 freezer from cgroup v1 freezer, which mostly
tried to imitate the system-wide freezer. However uninterruptible
sleep is fine when all tasks are going to be frozen (hibernation case),
it's not the acceptable state for some subset of the system.

Cgroup v2 freezer is not supporting freezing kthreads.
If a non-root cgroup contains kthread, the cgroup still can be frozen,
but the kthread will remain running, the cgroup will be shown
as non-frozen, and the notification will not be delivered.

* PTRACE_ATTACH is not working because non-fatal signal delivery
is blocked in frozen state.

There are some interface differences between cgroup v1 and cgroup v2
freezer too, which are required to conform the cgroup v2 interface
design principles:
1) There is no separate controller, which has to be turned on:
the functionality is always available and is represented by
cgroup.freeze and cgroup.events cgroup control files.
2) The desired state is defined by the cgroup.freeze control file.
Any hierarchical configuration is allowed.
3) The interface is asynchronous. The actual state is available
using cgroup.events control file ("frozen" field). There are no
dedicated transitional states.
4) It's allowed to make any changes with the cgroup hierarchy
(create new cgroups, remove old cgroups, move tasks between cgroups)
no matter if some cgroups are frozen.

Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
No-objection-from-me-by: Oleg Nesterov <oleg@redhat.com>
Cc: kernel-team@fb.com
2019-04-19 11:26:48 -07:00
Mathieu Desnoyers 83b0b15bcb rseq: Remove superfluous rseq_len from task_struct
The rseq system call, when invoked with flags of "0" or
"RSEQ_FLAG_UNREGISTER" values, expects the rseq_len parameter to
be equal to sizeof(struct rseq), which is fixed-size and fixed-layout,
specified in uapi linux/rseq.h.

Expecting a fixed size for rseq_len is a design choice that ensures
multiple libraries and application defining __rseq_abi in the same
process agree on its exact size.

Considering that this size is and will always be the same value, there
is no point in saving this value within task_struct rseq_len. Remove
this field from task_struct.

No change in functionality intended.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ben Maurer <bmaurer@fb.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Lameter <cl@linux.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-api@vger.kernel.org
Link: http://lkml.kernel.org/r/20190305194755.2602-3-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-19 12:39:32 +02:00
Linus Torvalds be37f21a08 audit/stable-5.1 PR 20190305
-----BEGIN PGP SIGNATURE-----
 
 iQJIBAABCAAyFiEES0KozwfymdVUl37v6iDy2pc3iXMFAlx+8ZgUHHBhdWxAcGF1
 bC1tb29yZS5jb20ACgkQ6iDy2pc3iXOlDhAAiGlirQ9syyG2fYzaARZZ2QoU/GGD
 PSAeiNmP3jvJzXArCvugRCw+YSNDdQOBM3SrLQC+cM0MAIDRYXN0NdcrsbTchlMA
 51Fx1egZ9Fyj+Ehgida3muh2lRUy7DQwMCL6tAVqwz7vYkSTGDUf+MlYqOqXDka5
 74pEExOS3Jdi7560BsE8b6QoW9JIJqEJnirXGkG9o2qC0oFHCR6PKxIyQ7TJrLR1
 F23aFTqLTH1nbPUQjnox2PTf13iQVh4j2gwzd+9c9KBfxoGSge3dmxId7BJHy2aG
 M27fPdCYTNZAGWpPVujsCPAh1WPQ9NQqg3mA9+g14PEbiLqPcqU+kWmnDU7T7bEw
 Qx0kt6Y8GiknwCqq8pDbKYclgRmOjSGdfutzd0z8uDpbaeunS4/NqnDb/FUaDVcr
 jA4d6ep7qEgHpYbL8KgOeZCexfaTfz6mcwRWNq3Uu9cLZbZqSSQ7PXolMADHvoRs
 LS7VH2jcP7q4p4GWmdfjv67xyUUo9HG5HHX74h5pLfQSYXiBWo4ht0UOAzX/6EcE
 CJNHAFHv+OanI5Rg/6JQ8b3/bJYxzAJVyLZpCuMtlKk6lYBGNeADk9BezEDIYsm8
 tSe4/GqqyR9+Qz8rSdpAZ0KKkfqS535IcHUPUJau7Bzg1xqSEP5gzZN6QsjdXg0+
 5wFFfdFICTfJFXo=
 =57/1
 -----END PGP SIGNATURE-----

Merge tag 'audit-pr-20190305' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit

Pull audit updates from Paul Moore:
 "A lucky 13 audit patches for v5.1.

  Despite the rather large diffstat, most of the changes are from two
  bug fix patches that move code from one Kconfig option to another.

  Beyond that bit of churn, the remaining changes are largely cleanups
  and bug-fixes as we slowly march towards container auditing. It isn't
  all boring though, we do have a couple of new things: file
  capabilities v3 support, and expanded support for filtering on
  filesystems to solve problems with remote filesystems.

  All changes pass the audit-testsuite.  Please merge for v5.1"

* tag 'audit-pr-20190305' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit:
  audit: mark expected switch fall-through
  audit: hide auditsc_get_stamp and audit_serial prototypes
  audit: join tty records to their syscall
  audit: remove audit_context when CONFIG_ AUDIT and not AUDITSYSCALL
  audit: remove unused actx param from audit_rule_match
  audit: ignore fcaps on umount
  audit: clean up AUDITSYSCALL prototypes and stubs
  audit: more filter PATH records keyed on filesystem magic
  audit: add support for fcaps v3
  audit: move loginuid and sessionid from CONFIG_AUDITSYSCALL to CONFIG_AUDIT
  audit: add syscall information to CONFIG_CHANGE records
  audit: hand taken context to audit_kill_trees for syscall logging
  audit: give a clue what CONFIG_CHANGE op was involved
2019-03-07 12:20:11 -08:00
Linus Torvalds 8dcd175bc3 Merge branch 'akpm' (patches from Andrew)
Merge misc updates from Andrew Morton:

 - a few misc things

 - ocfs2 updates

 - most of MM

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (159 commits)
  tools/testing/selftests/proc/proc-self-syscall.c: remove duplicate include
  proc: more robust bulk read test
  proc: test /proc/*/maps, smaps, smaps_rollup, statm
  proc: use seq_puts() everywhere
  proc: read kernel cpu stat pointer once
  proc: remove unused argument in proc_pid_lookup()
  fs/proc/thread_self.c: code cleanup for proc_setup_thread_self()
  fs/proc/self.c: code cleanup for proc_setup_self()
  proc: return exit code 4 for skipped tests
  mm,mremap: bail out earlier in mremap_to under map pressure
  mm/sparse: fix a bad comparison
  mm/memory.c: do_fault: avoid usage of stale vm_area_struct
  writeback: fix inode cgroup switching comment
  mm/huge_memory.c: fix "orig_pud" set but not used
  mm/hotplug: fix an imbalance with DEBUG_PAGEALLOC
  mm/memcontrol.c: fix bad line in comment
  mm/cma.c: cma_declare_contiguous: correct err handling
  mm/page_ext.c: fix an imbalance with kmemleak
  mm/compaction: pass pgdat to too_many_isolated() instead of zone
  mm: remove zone_lru_lock() function, access ->lru_lock directly
  ...
2019-03-06 10:31:36 -08:00
Linus Torvalds 45802da05e Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - refcount conversions

   - Solve the rq->leaf_cfs_rq_list can of worms for real.

   - improve power-aware scheduling

   - add sysctl knob for Energy Aware Scheduling

   - documentation updates

   - misc other changes"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
  kthread: Do not use TIMER_IRQSAFE
  kthread: Convert worker lock to raw spinlock
  sched/fair: Use non-atomic cpumask_{set,clear}_cpu()
  sched/fair: Remove unused 'sd' parameter from select_idle_smt()
  sched/wait: Use freezable_schedule() when possible
  sched/fair: Prune, fix and simplify the nohz_balancer_kick() comment block
  sched/fair: Explain LLC nohz kick condition
  sched/fair: Simplify nohz_balancer_kick()
  sched/topology: Fix percpu data types in struct sd_data & struct s_data
  sched/fair: Simplify post_init_entity_util_avg() by calling it with a task_struct pointer argument
  sched/fair: Fix O(nr_cgroups) in the load balancing path
  sched/fair: Optimize update_blocked_averages()
  sched/fair: Fix insertion in rq->leaf_cfs_rq_list
  sched/fair: Add tmp_alone_branch assertion
  sched/core: Use READ_ONCE()/WRITE_ONCE() in move_queued_task()/task_rq_lock()
  sched/debug: Initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK
  sched/pelt: Skip updating util_est when utilization is higher than CPU's capacity
  sched/fair: Update scale invariance of PELT
  sched/fair: Move the rq_of() helper function
  sched/core: Convert task_struct.stack_refcount to refcount_t
  ...
2019-03-06 08:14:05 -08:00
Aneesh Kumar K.V d7fefcc8de mm/cma: add PF flag to force non cma alloc
Patch series "mm/kvm/vfio/ppc64: Migrate compound pages out of CMA
region", v8.

ppc64 uses the CMA area for the allocation of guest page table (hash
page table).  We won't be able to start guest if we fail to allocate
hash page table.  We have observed hash table allocation failure because
we failed to migrate pages out of CMA region because they were pinned.
This happen when we are using VFIO.  VFIO on ppc64 pins the entire guest
RAM.  If the guest RAM pages get allocated out of CMA region, we won't
be able to migrate those pages.  The pages are also pinned for the
lifetime of the guest.

Currently we support migration of non-compound pages.  With THP and with
the addition of hugetlb migration we can end up allocating compound
pages from CMA region.  This patch series add support for migrating
compound pages.

This patch (of 4):

Add PF_MEMALLOC_NOCMA which make sure any allocation in that context is
marked non-movable and hence cannot be satisfied by CMA region.

This is useful with get_user_pages_longterm where we want to take a page
pin by migrating pages from CMA region.  Marking the section
PF_MEMALLOC_NOCMA ensures that we avoid unnecessary page migration
later.

Link: http://lkml.kernel.org/r/20190114095438.32470-2-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-05 21:07:19 -08:00
Mel Gorman 5e1f0f098b mm, compaction: capture a page under direct compaction
Compaction is inherently race-prone as a suitable page freed during
compaction can be allocated by any parallel task.  This patch uses a
capture_control structure to isolate a page immediately when it is freed
by a direct compactor in the slow path of the page allocator.  The
intent is to avoid redundant scanning.

                                     5.0.0-rc1              5.0.0-rc1
                               selective-v3r17          capture-v3r19
Amean     fault-both-1         0.00 (   0.00%)        0.00 *   0.00%*
Amean     fault-both-3      2582.11 (   0.00%)     2563.68 (   0.71%)
Amean     fault-both-5      4500.26 (   0.00%)     4233.52 (   5.93%)
Amean     fault-both-7      5819.53 (   0.00%)     6333.65 (  -8.83%)
Amean     fault-both-12     9321.18 (   0.00%)     9759.38 (  -4.70%)
Amean     fault-both-18     9782.76 (   0.00%)    10338.76 (  -5.68%)
Amean     fault-both-24    15272.81 (   0.00%)    13379.55 *  12.40%*
Amean     fault-both-30    15121.34 (   0.00%)    16158.25 (  -6.86%)
Amean     fault-both-32    18466.67 (   0.00%)    18971.21 (  -2.73%)

Latency is only moderately affected but the devil is in the details.  A
closer examination indicates that base page fault latency is reduced but
latency of huge pages is increased as it takes creater care to succeed.
Part of the "problem" is that allocation success rates are close to 100%
even when under pressure and compaction gets harder

                                5.0.0-rc1              5.0.0-rc1
                          selective-v3r17          capture-v3r19
Percentage huge-3        96.70 (   0.00%)       98.23 (   1.58%)
Percentage huge-5        96.99 (   0.00%)       95.30 (  -1.75%)
Percentage huge-7        94.19 (   0.00%)       97.24 (   3.24%)
Percentage huge-12       94.95 (   0.00%)       97.35 (   2.53%)
Percentage huge-18       96.74 (   0.00%)       97.30 (   0.58%)
Percentage huge-24       97.07 (   0.00%)       97.55 (   0.50%)
Percentage huge-30       95.69 (   0.00%)       98.50 (   2.95%)
Percentage huge-32       96.70 (   0.00%)       99.27 (   2.65%)

And scan rates are reduced as expected by 6% for the migration scanner
and 29% for the free scanner indicating that there is less redundant
work.

Compaction migrate scanned    20815362    19573286
Compaction free scanned       16352612    11510663

[mgorman@techsingularity.net: remove redundant check]
  Link: http://lkml.kernel.org/r/20190201143853.GH9565@techsingularity.net
Link: http://lkml.kernel.org/r/20190118175136.31341-23-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-05 21:07:17 -08:00
Linus Torvalds edaed168e1 Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86/pti update from Thomas Gleixner:
 "Just a single change from the anti-performance departement:

   - Add a new PR_SPEC_DISABLE_NOEXEC option which allows to apply the
     speculation protections on a process without inheriting the state
     on exec.

     This remedies a situation where a Java-launcher has speculation
     protections enabled because that's the default for JVMs which
     causes the launched regular harmless processes to inherit the
     protection state which results in unintended performance
     degradation"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation: Add PR_SPEC_DISABLE_NOEXEC
2019-03-05 12:50:34 -08:00
Linus Torvalds 53a41cb7ed Revert "x86/fault: BUG() when uaccess helpers fault on kernel addresses"
This reverts commit 9da3f2b740.

It was well-intentioned, but wrong.  Overriding the exception tables for
instructions for random reasons is just wrong, and that is what the new
code did.

It caused problems for tracing, and it caused problems for strncpy_from_user(),
because the new checks made perfectly valid use cases break, rather than
catch things that did bad things.

Unchecked user space accesses are a problem, but that's not a reason to
add invalid checks that then people have to work around with silly flags
(in this case, that 'kernel_uaccess_faults_ok' flag, which is just an
odd way to say "this commit was wrong" and was sprinked into random
places to hide the wrongness).

The real fix to unchecked user space accesses is to get rid of the
special "let's not check __get_user() and __put_user() at all" logic.
Make __{get|put}_user() be just aliases to the regular {get|put}_user()
functions, and make it impossible to access user space without having
the proper checks in places.

The raison d'être of the special double-underscore versions used to be
that the range check was expensive, and if you did multiple user
accesses, you'd do the range check up front (like the signal frame
handling code, for example).  But SMAP (on x86) and PAN (on ARM) have
made that optimization pointless, because the _real_ expense is the "set
CPU flag to allow user space access".

Do let's not break the valid cases to catch invalid cases that shouldn't
even exist.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tobin C. Harding <tobin@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-02-25 09:10:51 -08:00
Ingo Molnar c9ba7560c5 Linux 5.0-rc6
-----BEGIN PGP SIGNATURE-----
 
 iQFRBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAlxgqNUeHHRvcnZhbGRz
 QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiGwsoH+OVXu0NQofwTvVru
 8lgF3BSDG2mhf7mxbBBlBizGVy9jnjRNGCFMC+Jq8IwiFLwprja/G27kaDTkpuF1
 PHC3yfjKvjTeUP5aNdHlmxv6j1sSJfZl0y46DQal4UeTG/Giq8TFTi+Tbz7Wb/WV
 yCx4Lr8okAwTuNhnL8ojUCVIpd3c8QsyR9v6nEQ14Mj+MvEbokyTkMJV0bzOrM38
 JOB+/X1XY4JPZ6o3MoXrBca3bxbAJzMneq+9CWw1U5eiIG3msg4a+Ua3++RQMDNr
 8BP0yCZ6wo32S8uu0PI6HrZaBnLYi5g9Wh7Q7yc0mn1Uh1zWFykA6TtqK90agJeR
 A6Ktjw==
 =scY4
 -----END PGP SIGNATURE-----

Merge tag 'v5.0-rc6' into sched/core, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-11 08:01:50 +01:00
Andrea Parri c546951d9c sched/core: Use READ_ONCE()/WRITE_ONCE() in move_queued_task()/task_rq_lock()
move_queued_task() synchronizes with task_rq_lock() as follows:

	move_queued_task()		task_rq_lock()

	[S] ->on_rq = MIGRATING		[L] rq = task_rq()
	WMB (__set_task_cpu())		ACQUIRE (rq->lock);
	[S] ->cpu = new_cpu		[L] ->on_rq

where "[L] rq = task_rq()" is ordered before "ACQUIRE (rq->lock)" by an
address dependency and, in turn, "ACQUIRE (rq->lock)" is ordered before
"[L] ->on_rq" by the ACQUIRE itself.

Use READ_ONCE() to load ->cpu in task_rq() (c.f., task_cpu()) to honor
this address dependency.  Also, mark the accesses to ->cpu and ->on_rq
with READ_ONCE()/WRITE_ONCE() to comply with the LKMM.

Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/20190121155240.27173-1-andrea.parri@amarulasolutions.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 09:13:21 +01:00
Vincent Guittot 2312729688 sched/fair: Update scale invariance of PELT
The current implementation of load tracking invariance scales the
contribution with current frequency and uarch performance (only for
utilization) of the CPU. One main result of this formula is that the
figures are capped by current capacity of CPU. Another one is that the
load_avg is not invariant because not scaled with uarch.

The util_avg of a periodic task that runs r time slots every p time slots
varies in the range :

    U * (1-y^r)/(1-y^p) * y^i < Utilization < U * (1-y^r)/(1-y^p)

with U is the max util_avg value = SCHED_CAPACITY_SCALE

At a lower capacity, the range becomes:

    U * C * (1-y^r')/(1-y^p) * y^i' < Utilization <  U * C * (1-y^r')/(1-y^p)

with C reflecting the compute capacity ratio between current capacity and
max capacity.

so C tries to compensate changes in (1-y^r') but it can't be accurate.

Instead of scaling the contribution value of PELT algo, we should scale the
running time. The PELT signal aims to track the amount of computation of
tasks and/or rq so it seems more correct to scale the running time to
reflect the effective amount of computation done since the last update.

In order to be fully invariant, we need to apply the same amount of
running time and idle time whatever the current capacity. Because running
at lower capacity implies that the task will run longer, we have to ensure
that the same amount of idle time will be applied when system becomes idle
and no idle time has been "stolen". But reaching the maximum utilization
value (SCHED_CAPACITY_SCALE) means that the task is seen as an
always-running task whatever the capacity of the CPU (even at max compute
capacity). In this case, we can discard this "stolen" idle times which
becomes meaningless.

In order to achieve this time scaling, a new clock_pelt is created per rq.
The increase of this clock scales with current capacity when something
is running on rq and synchronizes with clock_task when rq is idle. With
this mechanism, we ensure the same running and idle time whatever the
current capacity. This also enables to simplify the pelt algorithm by
removing all references of uarch and frequency and applying the same
contribution to utilization and loads. Furthermore, the scaling is done
only once per update of clock (update_rq_clock_task()) instead of during
each update of sched_entities and cfs/rt/dl_rq of the rq like the current
implementation. This is interesting when cgroup are involved as shown in
the results below:

On a hikey (octo Arm64 platform).
Performance cpufreq governor and only shallowest c-state to remove variance
generated by those power features so we only track the impact of pelt algo.

each test runs 16 times:

	./perf bench sched pipe
	(higher is better)
	kernel	tip/sched/core     + patch
	        ops/seconds        ops/seconds         diff
	cgroup
	root    59652(+/- 0.18%)   59876(+/- 0.24%)    +0.38%
	level1  55608(+/- 0.27%)   55923(+/- 0.24%)    +0.57%
	level2  52115(+/- 0.29%)   52564(+/- 0.22%)    +0.86%

	hackbench -l 1000
	(lower is better)
	kernel	tip/sched/core     + patch
	        duration(sec)      duration(sec)        diff
	cgroup
	root    4.453(+/- 2.37%)   4.383(+/- 2.88%)     -1.57%
	level1  4.859(+/- 8.50%)   4.830(+/- 7.07%)     -0.60%
	level2  5.063(+/- 9.83%)   4.928(+/- 9.66%)     -2.66%

Then, the responsiveness of PELT is improved when CPU is not running at max
capacity with this new algorithm. I have put below some examples of
duration to reach some typical load values according to the capacity of the
CPU with current implementation and with this patch. These values has been
computed based on the geometric series and the half period value:

  Util (%)     max capacity  half capacity(mainline)  half capacity(w/ patch)
  972 (95%)    138ms         not reachable            276ms
  486 (47.5%)  30ms          138ms                     60ms
  256 (25%)    13ms           32ms                     26ms

On my hikey (octo Arm64 platform) with schedutil governor, the time to
reach max OPP when starting from a null utilization, decreases from 223ms
with current scale invariance down to 121ms with the new algorithm.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: patrick.bellasi@arm.com
Cc: pjt@google.com
Cc: pkondeti@codeaurora.org
Cc: quentin.perret@arm.com
Cc: rjw@rjwysocki.net
Cc: srinivas.pandruvada@linux.intel.com
Cc: thara.gopinath@linaro.org
Link: https://lkml.kernel.org/r/1548257214-13745-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 09:13:21 +01:00
Elena Reshetova f0b89d3958 sched/core: Convert task_struct.stack_refcount to refcount_t
atomic_t variables are currently used to implement reference
counters with the following properties:

 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable task_struct.stack_refcount is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

** Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.

The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.

Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.

Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the task_struct.stack_refcount it might make a difference
in following places:

 - try_get_task_stack(): increment in refcount_inc_not_zero() only
   guarantees control dependency on success vs. fully ordered
   atomic counterpart
 - put_task_stack(): decrement in refcount_dec_and_test() only
   provides RELEASE ordering and control dependency on success
   vs. fully ordered atomic counterpart

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1547814450-18902-6-git-send-email-elena.reshetova@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 08:53:56 +01:00
Elena Reshetova ec1d281923 sched/core: Convert task_struct.usage to refcount_t
atomic_t variables are currently used to implement reference
counters with the following properties:

 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable task_struct.usage is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

** Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts.

The full comparison can be seen in
https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon
in state to be merged to the documentation tree.

Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.

Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the task_struct.usage it might make a difference
in following places:

 - put_task_struct(): decrement in refcount_dec_and_test() only
   provides RELEASE ordering and control dependency on success
   vs. fully ordered atomic counterpart

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1547814450-18902-5-git-send-email-elena.reshetova@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 08:53:55 +01:00
Richard Guy Briggs 5f3d544f16 audit: remove audit_context when CONFIG_ AUDIT and not AUDITSYSCALL
Remove audit_context from struct task_struct and struct audit_buffer
when CONFIG_AUDIT is enabled but CONFIG_AUDITSYSCALL is not.

Also, audit_log_name() (and supporting inode and fcaps functions) should
have been put back in auditsc.c when soft and hard link logging was
normalized since it is only used by syscall auditing.

See github issue https://github.com/linux-audit/audit-kernel/issues/105

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-02-03 17:49:35 -05:00
Linus Torvalds 24b888d8d5 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Thomas Gleixner:
 "A few updates for x86:

   - Fix an unintended sign extension issue in the fault handling code

   - Rename the new resource control config switch so it's less
     confusing

   - Avoid setting up EFI info in kexec when the EFI runtime is
     disabled.

   - Fix the microcode version check in the AMD microcode loader so it
     only loads higher version numbers and never downgrades

   - Set EFER.LME in the 32bit trampoline before returning to long mode
     to handle older AMD/KVM behaviour properly.

   - Add Darren and Andy as x86/platform reviewers"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/resctrl: Avoid confusion over the new X86_RESCTRL config
  x86/kexec: Don't setup EFI info if EFI runtime is not enabled
  x86/microcode/amd: Don't falsely trick the late loading mechanism
  MAINTAINERS: Add Andy and Darren as arch/x86/platform/ reviewers
  x86/fault: Fix sign-extend unintended sign extension
  x86/boot/compressed/64: Set EFER.LME=1 in 32-bit trampoline before returning to long mode
  x86/cpu: Add Atom Tremont (Jacobsville)
2019-02-03 09:08:12 -08:00
Johannes Weiner e6d429313e x86/resctrl: Avoid confusion over the new X86_RESCTRL config
"Resource Control" is a very broad term for this CPU feature, and a term
that is also associated with containers, cgroups etc. This can easily
cause confusion.

Make the user prompt more specific. Match the config symbol name.

 [ bp: In the future, the corresponding ARM arch-specific code will be
   under ARM_CPU_RESCTRL and the arch-agnostic bits will be carved out
   under the CPU_RESCTRL umbrella symbol. ]

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Babu Moger <Babu.Moger@amd.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morse <james.morse@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: linux-doc@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pu Wen <puwen@hygon.cn>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190130195621.GA30653@cmpxchg.org
2019-02-02 10:34:52 +01:00
Waiman Long 71368af902 x86/speculation: Add PR_SPEC_DISABLE_NOEXEC
With the default SPEC_STORE_BYPASS_SECCOMP/SPEC_STORE_BYPASS_PRCTL mode,
the TIF_SSBD bit will be inherited when a new task is fork'ed or cloned.
It will also remain when a new program is execve'ed.

Only certain class of applications (like Java) that can run on behalf of
multiple users on a single thread will require disabling speculative store
bypass for security purposes. Those applications will call prctl(2) at
startup time to disable SSB. They won't rely on the fact the SSB might have
been disabled. Other applications that don't need SSBD will just move on
without checking if SSBD has been turned on or not.

The fact that the TIF_SSBD is inherited across execve(2) boundary will
cause performance of applications that don't need SSBD but their
predecessors have SSBD on to be unwittingly impacted especially if they
write to memory a lot.

To remedy this problem, a new PR_SPEC_DISABLE_NOEXEC argument for the
PR_SET_SPECULATION_CTRL option of prctl(2) is added to allow applications
to specify that the SSBD feature bit on the task structure should be
cleared whenever a new program is being execve'ed.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: KarimAllah Ahmed <karahmed@amazon.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: https://lkml.kernel.org/r/1547676096-3281-1-git-send-email-longman@redhat.com
2019-01-29 22:11:49 +01:00
Thomas Gleixner 15917dc028 sched: Remove stale PF_MUTEX_TESTER bit
The RTMUTEX tester was removed long ago but the PF bit stayed
around. Remove it and free up the space.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2019-01-29 20:14:28 +01:00
Richard Guy Briggs 4b7d248b3a audit: move loginuid and sessionid from CONFIG_AUDITSYSCALL to CONFIG_AUDIT
loginuid and sessionid (and audit_log_session_info) should be part of
CONFIG_AUDIT scope and not CONFIG_AUDITSYSCALL since it is used in
CONFIG_CHANGE, ANOM_LINK, FEATURE_CHANGE (and INTEGRITY_RULE), none of
which are otherwise dependent on AUDITSYSCALL.

Please see github issue
https://github.com/linux-audit/audit-kernel/issues/104

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: tweaked subject line for better grep'ing]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-01-25 13:03:23 -05:00
Linus Torvalds e8746440bf Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Pull networking fixes from David Miller:

 1) Fix regression in multi-SKB responses to RTM_GETADDR, from Arthur
    Gautier.

 2) Fix ipv6 frag parsing in openvswitch, from Yi-Hung Wei.

 3) Unbounded recursion in ipv4 and ipv6 GUE tunnels, from Stefano
    Brivio.

 4) Use after free in hns driver, from Yonglong Liu.

 5) icmp6_send() needs to handle the case of NULL skb, from Eric
    Dumazet.

 6) Missing rcu read lock in __inet6_bind() when operating on mapped
    addresses, from David Ahern.

 7) Memory leak in tipc-nl_compat_publ_dump(), from Gustavo A. R. Silva.

 8) Fix PHY vs r8169 module loading ordering issues, from Heiner
    Kallweit.

 9) Fix bridge vlan memory leak, from Ido Schimmel.

10) Dev refcount leak in AF_PACKET, from Jason Gunthorpe.

11) Infoleak in ipv6_local_error(), flow label isn't completely
    initialized. From Eric Dumazet.

12) Handle mv88e6390 errata, from Andrew Lunn.

13) Making vhost/vsock CID hashing consistent, from Zha Bin.

14) Fix lack of UMH cleanup when it unexpectedly exits, from Taehee Yoo.

15) Bridge forwarding must clear skb->tstamp, from Paolo Abeni.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (87 commits)
  bnxt_en: Fix context memory allocation.
  bnxt_en: Fix ring checking logic on 57500 chips.
  mISDN: hfcsusb: Use struct_size() in kzalloc()
  net: clear skb->tstamp in bridge forwarding path
  net: bpfilter: disallow to remove bpfilter module while being used
  net: bpfilter: restart bpfilter_umh when error occurred
  net: bpfilter: use cleanup callback to release umh_info
  umh: add exit routine for UMH process
  isdn: i4l: isdn_tty: Fix some concurrency double-free bugs
  vhost/vsock: fix vhost vsock cid hashing inconsistent
  net: stmmac: Prevent RX starvation in stmmac_napi_poll()
  net: stmmac: Fix the logic of checking if RX Watchdog must be enabled
  net: stmmac: Check if CBS is supported before configuring
  net: stmmac: dwxgmac2: Only clear interrupts that are active
  net: stmmac: Fix PCI module removal leak
  tools/bpf: fix bpftool map dump with bitfields
  tools/bpf: test btf bitfield with >=256 struct member offset
  bpf: fix bpffs bitfield pretty print
  net: ethernet: mediatek: fix warning in phy_start_aneg
  tcp: change txhash on SYN-data timeout
  ...
2019-01-16 05:13:36 +12:00
Taehee Yoo 73ab1cb2de umh: add exit routine for UMH process
A UMH process which is created by the fork_usermode_blob() such as
bpfilter needs to release members of the umh_info when process is
terminated.
But the do_exit() does not release members of the umh_info. hence module
which uses UMH needs own code to detect whether UMH process is
terminated or not.
But this implementation needs extra code for checking the status of
UMH process. it eventually makes the code more complex.

The new PF_UMH flag is added and it is used to identify UMH processes.
The exit_umh() does not release members of the umh_info.
Hence umh_info->cleanup callback should release both members of the
umh_info and the private data.

Suggested-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-01-11 18:05:40 -08:00
Borislav Petkov 90802938f7 x86/cache: Rename config option to CONFIG_X86_RESCTRL
CONFIG_RESCTRL is too generic. The final goal is to have a generic
option called like this which is selected by the arch-specific ones
CONFIG_X86_RESCTRL and CONFIG_ARM64_RESCTRL. The generic one will
cover the resctrl filesystem and other generic and shared bits of
functionality.

Signed-off-by: Borislav Petkov <bp@suse.de>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Requested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Babu Moger <babu.moger@amd.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: James Morse <james.morse@arm.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20190108171401.GC12235@zn.tnic
2019-01-09 10:29:03 +01:00
Linus Torvalds 17bf423a1f Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Introduce "Energy Aware Scheduling" - by Quentin Perret.

     This is a coherent topology description of CPUs in cooperation with
     the PM subsystem, with the goal to schedule more energy-efficiently
     on asymetric SMP platform - such as waking up tasks to the more
     energy-efficient CPUs first, as long as the system isn't
     oversubscribed.

     For details of the design, see:

        https://lore.kernel.org/lkml/20180724122521.22109-1-quentin.perret@arm.com/

   - Misc cleanups and smaller enhancements"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  sched/fair: Select an energy-efficient CPU on task wake-up
  sched/fair: Introduce an energy estimation helper function
  sched/fair: Add over-utilization/tipping point indicator
  sched/fair: Clean-up update_sg_lb_stats parameters
  sched/toplogy: Introduce the 'sched_energy_present' static key
  sched/topology: Make Energy Aware Scheduling depend on schedutil
  sched/topology: Disable EAS on inappropriate platforms
  sched/topology: Add lowest CPU asymmetry sched_domain level pointer
  sched/topology: Reference the Energy Model of CPUs when available
  PM: Introduce an Energy Model management framework
  sched/cpufreq: Prepare schedutil for Energy Aware Scheduling
  sched/topology: Relocate arch_scale_cpu_capacity() to the internal header
  sched/core: Remove unnecessary unlikely() in push_*_task()
  sched/topology: Remove the ::smt_gain field from 'struct sched_domain'
  sched: Fix various typos in comments
  sched/core: Clean up the #ifdef block in add_nr_running()
  sched/fair: Make some variables static
  sched/core: Create task_has_idle_policy() helper
  sched/fair: Add lsub_positive() and use it consistently
  sched/fair: Mask UTIL_AVG_UNCHANGED usages
  ...
2018-12-26 14:56:10 -08:00
Linus Torvalds 792bf4d871 Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:
 "The biggest RCU changes in this cycle were:

   - Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar.

   - Replace calls of RCU-bh and RCU-sched update-side functions to
     their vanilla RCU counterparts. This series is a step towards
     complete removal of the RCU-bh and RCU-sched update-side functions.

     ( Note that some of these conversions are going upstream via their
       respective maintainers. )

   - Documentation updates, including a number of flavor-consolidation
     updates from Joel Fernandes.

   - Miscellaneous fixes.

   - Automate generation of the initrd filesystem used for rcutorture
     testing.

   - Convert spin_is_locked() assertions to instead use lockdep.

     ( Note that some of these conversions are going upstream via their
       respective maintainers. )

   - SRCU updates, especially including a fix from Dennis Krein for a
     bag-on-head-class bug.

   - RCU torture-test updates"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (112 commits)
  rcutorture: Don't do busted forward-progress testing
  rcutorture: Use 100ms buckets for forward-progress callback histograms
  rcutorture: Recover from OOM during forward-progress tests
  rcutorture: Print forward-progress test age upon failure
  rcutorture: Print time since GP end upon forward-progress failure
  rcutorture: Print histogram of CB invocation at OOM time
  rcutorture: Print GP age upon forward-progress failure
  rcu: Print per-CPU callback counts for forward-progress failures
  rcu: Account for nocb-CPU callback counts in RCU CPU stall warnings
  rcutorture: Dump grace-period diagnostics upon forward-progress OOM
  rcutorture: Prepare for asynchronous access to rcu_fwd_startat
  torture: Remove unnecessary "ret" variables
  rcutorture: Affinity forward-progress test to avoid housekeeping CPUs
  rcutorture: Break up too-long rcu_torture_fwd_prog() function
  rcutorture: Remove cbflood facility
  torture: Bring any extra CPUs online during kernel startup
  rcutorture: Add call_rcu() flooding forward-progress tests
  rcutorture/formal: Replace synchronize_sched() with synchronize_rcu()
  tools/kernel.h: Replace synchronize_sched() with synchronize_rcu()
  net/decnet: Replace rcu_barrier_bh() with rcu_barrier()
  ...
2018-12-26 13:07:19 -08:00
Linus Torvalds a52fb43a5f Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cache control updates from Borislav Petkov:

 - The generalization of the RDT code to accommodate the addition of
   AMD's very similar implementation of the cache monitoring feature.

   This entails a subsystem move into a separate and generic
   arch/x86/kernel/cpu/resctrl/ directory along with adding
   vendor-specific initialization and feature detection helpers.

   Ontop of that is the unification of user-visible strings, both in the
   resctrl filesystem error handling and Kconfig.

   Provided by Babu Moger and Sherry Hurwitz.

 - Code simplifications and error handling improvements by Reinette
   Chatre.

* 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/resctrl: Fix rdt_find_domain() return value and checks
  x86/resctrl: Remove unnecessary check for cbm_validate()
  x86/resctrl: Use rdt_last_cmd_puts() where possible
  MAINTAINERS: Update resctrl filename patterns
  Documentation: Rename and update intel_rdt_ui.txt to resctrl_ui.txt
  x86/resctrl: Introduce AMD QOS feature
  x86/resctrl: Fixup the user-visible strings
  x86/resctrl: Add AMD's X86_FEATURE_MBA to the scattered CPUID features
  x86/resctrl: Rename the config option INTEL_RDT to RESCTRL
  x86/resctrl: Add vendor check for the MBA software controller
  x86/resctrl: Bring cbm_validate() into the resource structure
  x86/resctrl: Initialize the vendor-specific resource functions
  x86/resctrl: Move all the macros to resctrl/internal.h
  x86/resctrl: Re-arrange the RDT init code
  x86/resctrl: Rename the RDT functions and definitions
  x86/resctrl: Rename and move rdt files to a separate directory
2018-12-26 12:17:43 -08:00
Ingo Molnar 4bbfd7467c Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU changes from Paul E. McKenney:

- Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar.

- Replace calls of RCU-bh and RCU-sched update-side functions
  to their vanilla RCU counterparts.  This series is a step
  towards complete removal of the RCU-bh and RCU-sched update-side
  functions.

  ( Note that some of these conversions are going upstream via their
    respective maintainers. )

- Documentation updates, including a number of flavor-consolidation
  updates from Joel Fernandes.

- Miscellaneous fixes.

- Automate generation of the initrd filesystem used for
  rcutorture testing.

- Convert spin_is_locked() assertions to instead use lockdep.

  ( Note that some of these conversions are going upstream via their
    respective maintainers. )

- SRCU updates, especially including a fix from Dennis Krein
  for a bag-on-head-class bug.

- RCU torture-test updates.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-12-04 07:52:30 +01:00
Ingo Molnar dfcb245e28 sched: Fix various typos in comments
Go over the scheduler source code and fix common typos
in comments - and a typo in an actual variable name.

No change in functionality intended.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-12-03 11:55:42 +01:00
Linus Torvalds 4b78317679 Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull STIBP fallout fixes from Thomas Gleixner:
 "The performance destruction department finally got it's act together
  and came up with a cure for the STIPB regression:

   - Provide a command line option to control the spectre v2 user space
     mitigations. Default is either seccomp or prctl (if seccomp is
     disabled in Kconfig). prctl allows mitigation opt-in, seccomp
     enables the migitation for sandboxed processes.

   - Rework the code to handle the conditional STIBP/IBPB control and
     remove the now unused ptrace_may_access_sched() optimization
     attempt

   - Disable STIBP automatically when SMT is disabled

   - Optimize the switch_to() logic to avoid MSR writes and invocations
     of __switch_to_xtra().

   - Make the asynchronous speculation TIF updates synchronous to
     prevent stale mitigation state.

  As a general cleanup this also makes retpoline directly depend on
  compiler support and removes the 'minimal retpoline' option which just
  pretended to provide some form of security while providing none"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
  x86/speculation: Provide IBPB always command line options
  x86/speculation: Add seccomp Spectre v2 user space protection mode
  x86/speculation: Enable prctl mode for spectre_v2_user
  x86/speculation: Add prctl() control for indirect branch speculation
  x86/speculation: Prepare arch_smt_update() for PRCTL mode
  x86/speculation: Prevent stale SPEC_CTRL msr content
  x86/speculation: Split out TIF update
  ptrace: Remove unused ptrace_may_access_sched() and MODE_IBRS
  x86/speculation: Prepare for conditional IBPB in switch_mm()
  x86/speculation: Avoid __switch_to_xtra() calls
  x86/process: Consolidate and simplify switch_to_xtra() code
  x86/speculation: Prepare for per task indirect branch speculation control
  x86/speculation: Add command line control for indirect branch speculation
  x86/speculation: Unify conditional spectre v2 print functions
  x86/speculataion: Mark command line parser data __initdata
  x86/speculation: Mark string arrays const correctly
  x86/speculation: Reorder the spec_v2 code
  x86/l1tf: Show actual SMT state
  x86/speculation: Rework SMT state change
  sched/smt: Expose sched_smt_present static key
  ...
2018-12-01 12:35:48 -08:00
Thomas Gleixner 9137bb27e6 x86/speculation: Add prctl() control for indirect branch speculation
Add the PR_SPEC_INDIRECT_BRANCH option for the PR_GET_SPECULATION_CTRL and
PR_SET_SPECULATION_CTRL prctls to allow fine grained per task control of
indirect branch speculation via STIBP and IBPB.

Invocations:
 Check indirect branch speculation status with
 - prctl(PR_GET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, 0, 0, 0);

 Enable indirect branch speculation with
 - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_ENABLE, 0, 0);

 Disable indirect branch speculation with
 - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_DISABLE, 0, 0);

 Force disable indirect branch speculation with
 - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_FORCE_DISABLE, 0, 0);

See Documentation/userspace-api/spec_ctrl.rst.

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Casey Schaufler <casey.schaufler@intel.com>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Waiman Long <longman9394@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Dave Stewart <david.c.stewart@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181125185005.866780996@linutronix.de
2018-11-28 11:57:13 +01:00
Steven Rostedt (VMware) 39eb456dac function_graph: Use new curr_ret_depth to manage depth instead of curr_ret_stack
Currently, the depth of the ret_stack is determined by curr_ret_stack index.
The issue is that there's a race between setting of the curr_ret_stack and
calling of the callback attached to the return of the function.

Commit 03274a3ffb ("tracing/fgraph: Adjust fgraph depth before calling
trace return callback") moved the calling of the callback to after the
setting of the curr_ret_stack, even stating that it was safe to do so, when
in fact, it was the reason there was a barrier() there (yes, I should have
commented that barrier()).

Not only does the curr_ret_stack keep track of the current call graph depth,
it also keeps the ret_stack content from being overwritten by new data.

The function profiler, uses the "subtime" variable of ret_stack structure
and by moving the curr_ret_stack, it allows for interrupts to use the same
structure it was using, corrupting the data, and breaking the profiler.

To fix this, there needs to be two variables to handle the call stack depth
and the pointer to where the ret_stack is being used, as they need to change
at two different locations.

Cc: stable@kernel.org
Fixes: 03274a3ffb ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-11-27 20:31:54 -05:00
Babu Moger 6fe07ce35e x86/resctrl: Rename the config option INTEL_RDT to RESCTRL
The resource control feature is supported by both Intel and AMD. So,
rename CONFIG_INTEL_RDT to the vendor-neutral CONFIG_RESCTRL.

Now CONFIG_RESCTRL will be used for both Intel and AMD to enable
Resource Control support. Update the texts in config and condition
accordingly.

 [ bp: Simplify Kconfig text. ]

Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: "Chang S. Bae" <chang.seok.bae@intel.com>
Cc: David Miller <davem@davemloft.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Dmitry Safonov <dima@arista.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <linux-doc@vger.kernel.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Pu Wen <puwen@hygon.cn>
Cc: <qianyue.zj@alibaba-inc.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Rian Hunter <rian@alum.mit.edu>
Cc: Sherry Hurwitz <sherry.hurwitz@amd.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Lendacky <Thomas.Lendacky@amd.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: <xiaochen.shen@intel.com>
Link: https://lkml.kernel.org/r/20181121202811.4492-9-babu.moger@amd.com
2018-11-22 20:16:19 +01:00
Paul E. McKenney 05f415715c rcu: Speed up expedited GPs when interrupting RCU reader
In PREEMPT kernels, an expedited grace period might send an IPI to a
CPU that is executing an RCU read-side critical section.  In that case,
it would be nice if the rcu_read_unlock() directly interacted with the
RCU core code to immediately report the quiescent state.  And this does
happen in the case where the reader has been preempted.  But it would
also be a nice performance optimization if immediate reporting also
happened in the preemption-free case.

This commit therefore adds an ->exp_hint field to the task_struct structure's
->rcu_read_unlock_special field.  The IPI handler sets this hint when
it has interrupted an RCU read-side critical section, and this causes
the outermost rcu_read_unlock() call to invoke rcu_read_unlock_special(),
which, if preemption is enabled, reports the quiescent state immediately.
If preemption is disabled, then the report is required to be deferred
until preemption (or bottom halves or interrupts or whatever) is re-enabled.

Because this is a hint, it does nothing for more complicated cases.  For
example, if the IPI interrupts an RCU reader, but interrupts are disabled
across the rcu_read_unlock(), but another rcu_read_lock() is executed
before interrupts are re-enabled, the hint will already have been cleared.
If you do crazy things like this, reporting will be deferred until some
later RCU_SOFTIRQ handler, context switch, cond_resched(), or similar.

Reported-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org>
2018-11-12 09:03:59 -08:00
Linus Torvalds 2d6bb6adb7 New gcc plugin: stackleak
- Introduces the stackleak gcc plugin ported from grsecurity by Alexander
   Popov, with x86 and arm64 support.
 -----BEGIN PGP SIGNATURE-----
 Comment: Kees Cook <kees@outflux.net>
 
 iQJKBAABCgA0FiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAlvQvn4WHGtlZXNjb29r
 QGNocm9taXVtLm9yZwAKCRCJcvTf3G3AJpSfD/sErFreuPT1beSw994Lr9Zx4k9v
 ERsuXxWBENaJOJXbOOHMfVEcEeG/1uhPSp7hlw/dpHfh0anATTrcYqm8RNKbfK+k
 o06+JK14OJfpm5Ghq/7OizhdNLCMT8wMU3XZtWfy65VSJGjEFx8Y48vMeQtpWtUK
 ylSzi9JV6j2iUBF9oibtiT53+yqsqAtX80X1G7HRCgv9kxuKMhZr+Q5oGV6+ViyQ
 Azj8mNn06iRnhHKd17WxDJr0GjSibzz4weS/9XgP3t3EcNWJo1EgBlD2KV3tOfP5
 nzmqfqTqrcjxs/tyjdh6vVCSlYucNtyCQGn63qyShQYSg6mZwclR2fY8YSTw6PWw
 GfYWFOWru9z+qyQmwFkQ9bSQS2R+JIT0oBCj9VmtF9XmPCy7K2neJsQclzSPBiCW
 wPgXVQS4IA4684O5CmDOVMwmDpGvhdBNUR6cqSzGLxQOHY1csyXubMNUsqU3g9xk
 Ob4pEy/xrrIw4WpwHcLHSEW5gV1/OLhsT0fGRJJiC947L3cN5s9EZp7FLbIS0zlk
 qzaXUcLmn6AgcfkYwg5cI3RMLaN2V0eDCMVTWZJ1wbrmUV9chAaOnTPTjNqLOTht
 v3b1TTxXG4iCpMmOFf59F8pqgAwbBDlfyNSbySZ/Pq5QH69udz3Z9pIUlYQnSJHk
 u6q++2ReDpJXF81rBw==
 =Ks6B
 -----END PGP SIGNATURE-----

Merge tag 'stackleak-v4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull stackleak gcc plugin from Kees Cook:
 "Please pull this new GCC plugin, stackleak, for v4.20-rc1. This plugin
  was ported from grsecurity by Alexander Popov. It provides efficient
  stack content poisoning at syscall exit. This creates a defense
  against at least two classes of flaws:

   - Uninitialized stack usage. (We continue to work on improving the
     compiler to do this in other ways: e.g. unconditional zero init was
     proposed to GCC and Clang, and more plugin work has started too).

   - Stack content exposure. By greatly reducing the lifetime of valid
     stack contents, exposures via either direct read bugs or unknown
     cache side-channels become much more difficult to exploit. This
     complements the existing buddy and heap poisoning options, but
     provides the coverage for stacks.

  The x86 hooks are included in this series (which have been reviewed by
  Ingo, Dave Hansen, and Thomas Gleixner). The arm64 hooks have already
  been merged through the arm64 tree (written by Laura Abbott and
  reviewed by Mark Rutland and Will Deacon).

  With VLAs having been removed this release, there is no need for
  alloca() protection, so it has been removed from the plugin"

* tag 'stackleak-v4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  arm64: Drop unneeded stackleak_check_alloca()
  stackleak: Allow runtime disabling of kernel stack erasing
  doc: self-protection: Add information about STACKLEAK feature
  fs/proc: Show STACKLEAK metrics in the /proc file system
  lkdtm: Add a test for STACKLEAK
  gcc-plugins: Add STACKLEAK plugin for tracking the kernel stack
  x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls
2018-11-01 11:46:27 -07:00
Shakeel Butt 85cfb24506 memcg: remove memcg_kmem_skip_account
The flag memcg_kmem_skip_account was added during the era of opt-out kmem
accounting.  There is no need for such flag in the opt-in world as there
aren't any __GFP_ACCOUNT allocations within memcg_create_cache_enqueue().

Link: http://lkml.kernel.org/r/20180919004501.178023-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 16:26:33 -07:00
Johannes Weiner eb414681d5 psi: pressure stall information for CPU, memory, and IO
When systems are overcommitted and resources become contended, it's hard
to tell exactly the impact this has on workload productivity, or how close
the system is to lockups and OOM kills.  In particular, when machines work
multiple jobs concurrently, the impact of overcommit in terms of latency
and throughput on the individual job can be enormous.

In order to maximize hardware utilization without sacrificing individual
job health or risk complete machine lockups, this patch implements a way
to quantify resource pressure in the system.

A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that
expose the percentage of time the system is stalled on CPU, memory, or IO,
respectively.  Stall states are aggregate versions of the per-task delay
accounting delays:

       cpu: some tasks are runnable but not executing on a CPU
       memory: tasks are reclaiming, or waiting for swapin or thrashing cache
       io: tasks are waiting for io completions

These percentages of walltime can be thought of as pressure percentages,
and they give a general sense of system health and productivity loss
incurred by resource overcommit.  They can also indicate when the system
is approaching lockup scenarios and OOMs.

To do this, psi keeps track of the task states associated with each CPU
and samples the time they spend in stall states.  Every 2 seconds, the
samples are averaged across CPUs - weighted by the CPUs' non-idle time to
eliminate artifacts from unused CPUs - and translated into percentages of
walltime.  A running average of those percentages is maintained over 10s,
1m, and 5m periods (similar to the loadaverage).

[hannes@cmpxchg.org: doc fixlet, per Randy]
  Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org
[hannes@cmpxchg.org: code optimization]
  Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org
[hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter]
  Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org
[hannes@cmpxchg.org: fix build]
  Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26 16:26:32 -07:00
Linus Torvalds ba9f6f8954 Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull siginfo updates from Eric Biederman:
 "I have been slowly sorting out siginfo and this is the culmination of
  that work.

  The primary result is in several ways the signal infrastructure has
  been made less error prone. The code has been updated so that manually
  specifying SEND_SIG_FORCED is never necessary. The conversion to the
  new siginfo sending functions is now complete, which makes it
  difficult to send a signal without filling in the proper siginfo
  fields.

  At the tail end of the patchset comes the optimization of decreasing
  the size of struct siginfo in the kernel from 128 bytes to about 48
  bytes on 64bit. The fundamental observation that enables this is by
  definition none of the known ways to use struct siginfo uses the extra
  bytes.

  This comes at the cost of a small user space observable difference.
  For the rare case of siginfo being injected into the kernel only what
  can be copied into kernel_siginfo is delivered to the destination, the
  rest of the bytes are set to 0. For cases where the signal and the
  si_code are known this is safe, because we know those bytes are not
  used. For cases where the signal and si_code combination is unknown
  the bits that won't fit into struct kernel_siginfo are tested to
  verify they are zero, and the send fails if they are not.

  I made an extensive search through userspace code and I could not find
  anything that would break because of the above change. If it turns out
  I did break something it will take just the revert of a single change
  to restore kernel_siginfo to the same size as userspace siginfo.

  Testing did reveal dependencies on preferring the signo passed to
  sigqueueinfo over si->signo, so bit the bullet and added the
  complexity necessary to handle that case.

  Testing also revealed bad things can happen if a negative signal
  number is passed into the system calls. Something no sane application
  will do but something a malicious program or a fuzzer might do. So I
  have fixed the code that performs the bounds checks to ensure negative
  signal numbers are handled"

* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (80 commits)
  signal: Guard against negative signal numbers in copy_siginfo_from_user32
  signal: Guard against negative signal numbers in copy_siginfo_from_user
  signal: In sigqueueinfo prefer sig not si_signo
  signal: Use a smaller struct siginfo in the kernel
  signal: Distinguish between kernel_siginfo and siginfo
  signal: Introduce copy_siginfo_from_user and use it's return value
  signal: Remove the need for __ARCH_SI_PREABLE_SIZE and SI_PAD_SIZE
  signal: Fail sigqueueinfo if si_signo != sig
  signal/sparc: Move EMT_TAGOVF into the generic siginfo.h
  signal/unicore32: Use force_sig_fault where appropriate
  signal/unicore32: Generate siginfo in ucs32_notify_die
  signal/unicore32: Use send_sig_fault where appropriate
  signal/arc: Use force_sig_fault where appropriate
  signal/arc: Push siginfo generation into unhandled_exception
  signal/ia64: Use force_sig_fault where appropriate
  signal/ia64: Use the force_sig(SIGSEGV,...) in ia64_rt_sigreturn
  signal/ia64: Use the generic force_sigsegv in setup_frame
  signal/arm/kvm: Use send_sig_mceerr
  signal/arm: Use send_sig_fault where appropriate
  signal/arm: Use force_sig_fault where appropriate
  ...
2018-10-24 11:22:39 +01:00
Linus Torvalds 0200fbdd43 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking and misc x86 updates from Ingo Molnar:
 "Lots of changes in this cycle - in part because locking/core attracted
  a number of related x86 low level work which was easier to handle in a
  single tree:

   - Linux Kernel Memory Consistency Model updates (Alan Stern, Paul E.
     McKenney, Andrea Parri)

   - lockdep scalability improvements and micro-optimizations (Waiman
     Long)

   - rwsem improvements (Waiman Long)

   - spinlock micro-optimization (Matthew Wilcox)

   - qspinlocks: Provide a liveness guarantee (more fairness) on x86.
     (Peter Zijlstra)

   - Add support for relative references in jump tables on arm64, x86
     and s390 to optimize jump labels (Ard Biesheuvel, Heiko Carstens)

   - Be a lot less permissive on weird (kernel address) uaccess faults
     on x86: BUG() when uaccess helpers fault on kernel addresses (Jann
     Horn)

   - macrofy x86 asm statements to un-confuse the GCC inliner. (Nadav
     Amit)

   - ... and a handful of other smaller changes as well"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (57 commits)
  locking/lockdep: Make global debug_locks* variables read-mostly
  locking/lockdep: Fix debug_locks off performance problem
  locking/pvqspinlock: Extend node size when pvqspinlock is configured
  locking/qspinlock_stat: Count instances of nested lock slowpaths
  locking/qspinlock, x86: Provide liveness guarantee
  x86/asm: 'Simplify' GEN_*_RMWcc() macros
  locking/qspinlock: Rework some comments
  locking/qspinlock: Re-order code
  locking/lockdep: Remove duplicated 'lock_class_ops' percpu array
  x86/defconfig: Enable CONFIG_USB_XHCI_HCD=y
  futex: Replace spin_is_locked() with lockdep
  locking/lockdep: Make class->ops a percpu counter and move it under CONFIG_DEBUG_LOCKDEP=y
  x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs
  x86/cpufeature: Macrofy inline assembly code to work around GCC inlining bugs
  x86/extable: Macrofy inline assembly code to work around GCC inlining bugs
  x86/paravirt: Work around GCC inlining bugs when compiling paravirt ops
  x86/bug: Macrofy the BUG table section handling, to work around GCC inlining bugs
  x86/alternatives: Macrofy lock prefixes to work around GCC inlining bugs
  x86/refcount: Work around GCC inlining bug
  x86/objtool: Use asm macros to work around GCC inlining bugs
  ...
2018-10-23 13:08:53 +01:00
Eric W. Biederman ae7795bc61 signal: Distinguish between kernel_siginfo and siginfo
Linus recently observed that if we did not worry about the padding
member in struct siginfo it is only about 48 bytes, and 48 bytes is
much nicer than 128 bytes for allocating on the stack and copying
around in the kernel.

The obvious thing of only adding the padding when userspace is
including siginfo.h won't work as there are sigframe definitions in
the kernel that embed struct siginfo.

So split siginfo in two; kernel_siginfo and siginfo.  Keeping the
traditional name for the userspace definition.  While the version that
is used internally to the kernel and ultimately will not be padded to
128 bytes is called kernel_siginfo.

The definition of struct kernel_siginfo I have put in include/signal_types.h

A set of buildtime checks has been added to verify the two structures have
the same field offsets.

To make it easy to verify the change kernel_siginfo retains the same
size as siginfo.  The reduction in size comes in a following change.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-10-03 16:47:43 +02:00
Alexander Popov c8d126275a fs/proc: Show STACKLEAK metrics in the /proc file system
Introduce CONFIG_STACKLEAK_METRICS providing STACKLEAK information about
tasks via the /proc file system. In particular, /proc/<pid>/stack_depth
shows the maximum kernel stack consumption for the current and previous
syscalls. Although this information is not precise, it can be useful for
estimating the STACKLEAK performance impact for your workloads.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
2018-09-04 10:35:48 -07:00
Alexander Popov afaef01c00 x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls
The STACKLEAK feature (initially developed by PaX Team) has the following
benefits:

1. Reduces the information that can be revealed through kernel stack leak
   bugs. The idea of erasing the thread stack at the end of syscalls is
   similar to CONFIG_PAGE_POISONING and memzero_explicit() in kernel
   crypto, which all comply with FDP_RIP.2 (Full Residual Information
   Protection) of the Common Criteria standard.

2. Blocks some uninitialized stack variable attacks (e.g. CVE-2017-17712,
   CVE-2010-2963). That kind of bugs should be killed by improving C
   compilers in future, which might take a long time.

This commit introduces the code filling the used part of the kernel
stack with a poison value before returning to userspace. Full
STACKLEAK feature also contains the gcc plugin which comes in a
separate commit.

The STACKLEAK feature is ported from grsecurity/PaX. More information at:
  https://grsecurity.net/
  https://pax.grsecurity.net/

This code is modified from Brad Spengler/PaX Team's code in the last
public patch of grsecurity/PaX based on our understanding of the code.
Changes or omissions from the original code are ours and don't reflect
the original grsecurity/PaX code.

Performance impact:

Hardware: Intel Core i7-4770, 16 GB RAM

Test #1: building the Linux kernel on a single core
        0.91% slowdown

Test #2: hackbench -s 4096 -l 2000 -g 15 -f 25 -P
        4.2% slowdown

So the STACKLEAK description in Kconfig includes: "The tradeoff is the
performance impact: on a single CPU system kernel compilation sees a 1%
slowdown, other systems and workloads may vary and you are advised to
test this feature on your expected workload before deploying it".

Signed-off-by: Alexander Popov <alex.popov@linux.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
2018-09-04 10:35:47 -07:00
Jann Horn 9da3f2b740 x86/fault: BUG() when uaccess helpers fault on kernel addresses
There have been multiple kernel vulnerabilities that permitted userspace to
pass completely unchecked pointers through to userspace accessors:

 - the waitid() bug - commit 96ca579a1e ("waitid(): Add missing
   access_ok() checks")
 - the sg/bsg read/write APIs
 - the infiniband read/write APIs

These don't happen all that often, but when they do happen, it is hard to
test for them properly; and it is probably also hard to discover them with
fuzzing. Even when an unmapped kernel address is supplied to such buggy
code, it just returns -EFAULT instead of doing a proper BUG() or at least
WARN().

Try to make such misbehaving code a bit more visible by refusing to do a
fixup in the pagefault handler code when a userspace accessor causes a #PF
on a kernel address and the current context isn't whitelisted.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: dvyukov@google.com
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lkml.kernel.org/r/20180828201421.157735-7-jannh@google.com
2018-09-03 15:12:09 +02:00
Paul E. McKenney fcc878e4df rcu: Remove now-unused ->b.exp_need_qs field from the rcu_special union
The ->b.exp_need_qs field is now set only to false, so this commit
removes it.  The job this field used to do is now done by the rcu_data
structure's ->deferred_qs field, which is a consequence of a better
split between task-based (the rcu_node structure's ->exp_tasks field) and
CPU-based (the aforementioned rcu_data structure's ->deferred_qs field)
tracking of quiescent states for RCU-preempt expedited grace periods.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2018-08-30 16:02:36 -07:00
Linus Torvalds cd9b44f907 Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton:

 - the rest of MM

 - procfs updates

 - various misc things

 - more y2038 fixes

 - get_maintainer updates

 - lib/ updates

 - checkpatch updates

 - various epoll updates

 - autofs updates

 - hfsplus

 - some reiserfs work

 - fatfs updates

 - signal.c cleanups

 - ipc/ updates

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (166 commits)
  ipc/util.c: update return value of ipc_getref from int to bool
  ipc/util.c: further variable name cleanups
  ipc: simplify ipc initialization
  ipc: get rid of ids->tables_initialized hack
  lib/rhashtable: guarantee initial hashtable allocation
  lib/rhashtable: simplify bucket_table_alloc()
  ipc: drop ipc_lock()
  ipc/util.c: correct comment in ipc_obtain_object_check
  ipc: rename ipcctl_pre_down_nolock()
  ipc/util.c: use ipc_rcu_putref() for failues in ipc_addid()
  ipc: reorganize initialization of kern_ipc_perm.seq
  ipc: compute kern_ipc_perm.id under the ipc lock
  init/Kconfig: remove EXPERT from CHECKPOINT_RESTORE
  fs/sysv/inode.c: use ktime_get_real_seconds() for superblock stamp
  adfs: use timespec64 for time conversion
  kernel/sysctl.c: fix typos in comments
  drivers/rapidio/devices/rio_mport_cdev.c: remove redundant pointer md
  fork: don't copy inconsistent signal handler state to child
  signal: make get_signal() return bool
  signal: make sigkill_pending() return bool
  ...
2018-08-22 12:34:08 -07:00
Dmitry Vyukov a2e5144538 kernel/hung_task.c: allow to set checking interval separately from timeout
Currently task hung checking interval is equal to timeout, as the result
hung is detected anywhere between timeout and 2*timeout.  This is fine for
most interactive environments, but this hurts automated testing setups
(syzbot).  In an automated setup we need to strictly order CPU lockup <
RCU stall < workqueue lockup < task hung < silent loss, so that RCU stall
is not detected as task hung and task hung is not detected as silent
machine loss.  The large variance in task hung detection timeout requires
setting silent machine loss timeout to a very large value (e.g.  if task
hung is 3 mins, then silent loss need to be set to ~7 mins).  The
additional 3 minutes significantly reduce testing efficiency because
usually we crash kernel within a minute, and this can add hours to bug
localization process as it needs to do dozens of tests.

Allow setting checking interval separately from timeout.  This allows to
set timeout to, say, 3 minutes, but checking interval to 10 secs.

The interval is controlled via a new hung_task_check_interval_secs sysctl,
similar to the existing hung_task_timeout_secs sysctl.  The default value
of 0 results in the current behavior: checking interval is equal to
timeout.

[akpm@linux-foundation.org: update hung_task_timeout_max's comment]
Link: http://lkml.kernel.org/r/20180611111004.203513-1-dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:47 -07:00
Linus Torvalds 0214f46b3a Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull core signal handling updates from Eric Biederman:
 "It was observed that a periodic timer in combination with a
  sufficiently expensive fork could prevent fork from every completing.
  This contains the changes to remove the need for that restart.

  This set of changes is split into several parts:

   - The first part makes PIDTYPE_TGID a proper pid type instead
     something only for very special cases. The part starts using
     PIDTYPE_TGID enough so that in __send_signal where signals are
     actually delivered we know if the signal is being sent to a a group
     of processes or just a single process.

   - With that prep work out of the way the logic in fork is modified so
     that fork logically makes signals received while it is running
     appear to be received after the fork completes"

* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (22 commits)
  signal: Don't send signals to tasks that don't exist
  signal: Don't restart fork when signals come in.
  fork: Have new threads join on-going signal group stops
  fork: Skip setting TIF_SIGPENDING in ptrace_init_task
  signal: Add calculate_sigpending()
  fork: Unconditionally exit if a fatal signal is pending
  fork: Move and describe why the code examines PIDNS_ADDING
  signal: Push pid type down into complete_signal.
  signal: Push pid type down into __send_signal
  signal: Push pid type down into send_signal
  signal: Pass pid type into do_send_sig_info
  signal: Pass pid type into send_sigio_to_task & send_sigurg_to_task
  signal: Pass pid type into group_send_sig_info
  signal: Pass pid and pid type into send_sigqueue
  posix-timers: Noralize good_sigevent
  signal: Use PIDTYPE_TGID to clearly store where file signals will be sent
  pid: Implement PIDTYPE_TGID
  pids: Move the pgrp and session pid pointers from task_struct to signal_struct
  kvm: Don't open code task_pid in kvm_vcpu_ioctl
  pids: Compute task_tgid using signal->leader_pid
  ...
2018-08-21 13:47:29 -07:00
Kirill Tkhai 84c07d11aa mm: introduce CONFIG_MEMCG_KMEM as combination of CONFIG_MEMCG && !CONFIG_SLOB
Introduce new config option, which is used to replace repeating
CONFIG_MEMCG && !CONFIG_SLOB pattern.  Next patches add a little more
memcg+kmem related code, so let's keep the defines more clearly.

Link: http://lkml.kernel.org/r/153063053670.1818.15013136946600481138.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-17 16:20:30 -07:00
Michal Hocko 29ef680ae7 memcg, oom: move out_of_memory back to the charge path
Commit 3812c8c8f3 ("mm: memcg: do not trap chargers with full
callstack on OOM") has changed the ENOMEM semantic of memcg charges.
Rather than invoking the oom killer from the charging context it delays
the oom killer to the page fault path (pagefault_out_of_memory).  This
in turn means that many users (e.g.  slab or g-u-p) will get ENOMEM when
the corresponding memcg hits the hard limit and the memcg is is OOM.
This is behavior is inconsistent with !memcg case where the oom killer
is invoked from the allocation context and the allocator keeps retrying
until it succeeds.

The difference in the behavior is user visible.  mmap(MAP_POPULATE)
might result in not fully populated ranges while the mmap return code
doesn't tell that to the userspace.  Random syscalls might fail with
ENOMEM etc.

The primary motivation of the different memcg oom semantic was the
deadlock avoidance.  Things have changed since then, though.  We have an
async oom teardown by the oom reaper now and so we do not have to rely
on the victim to tear down its memory anymore.  Therefore we can return
to the original semantic as long as the memcg oom killer is not handed
over to the users space.

There is still one thing to be careful about here though.  If the oom
killer is not able to make any forward progress - e.g.  because there is
no eligible task to kill - then we have to bail out of the charge path
to prevent from same class of deadlocks.  We have basically two options
here.  Either we fail the charge with ENOMEM or force the charge and
allow overcharge.  The first option has been considered more harmful
than useful because rare inconsistencies in the ENOMEM behavior is hard
to test for and error prone.  Basically the same reason why the page
allocator doesn't fail allocations under such conditions.  The later
might allow runaways but those should be really unlikely unless somebody
misconfigures the system.  E.g.  allowing to migrate tasks away from the
memcg to a different unlimited memcg with move_charge_at_immigrate
disabled.

Link: http://lkml.kernel.org/r/20180628151101.25307-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-17 16:20:30 -07:00
Shakeel Butt d46eb14b73 fs: fsnotify: account fsnotify metadata to kmemcg
Patch series "Directed kmem charging", v8.

The Linux kernel's memory cgroup allows limiting the memory usage of the
jobs running on the system to provide isolation between the jobs.  All
the kernel memory allocated in the context of the job and marked with
__GFP_ACCOUNT will also be included in the memory usage and be limited
by the job's limit.

The kernel memory can only be charged to the memcg of the process in
whose context kernel memory was allocated.  However there are cases
where the allocated kernel memory should be charged to the memcg
different from the current processes's memcg.  This patch series
contains two such concrete use-cases i.e.  fsnotify and buffer_head.

The fsnotify event objects can consume a lot of system memory for large
or unlimited queues if there is either no or slow listener.  The events
are allocated in the context of the event producer.  However they should
be charged to the event consumer.  Similarly the buffer_head objects can
be allocated in a memcg different from the memcg of the page for which
buffer_head objects are being allocated.

To solve this issue, this patch series introduces mechanism to charge
kernel memory to a given memcg.  In case of fsnotify events, the memcg
of the consumer can be used for charging and for buffer_head, the memcg
of the page can be charged.  For directed charging, the caller can use
the scope API memalloc_[un]use_memcg() to specify the memcg to charge
for all the __GFP_ACCOUNT allocations within the scope.

This patch (of 2):

A lot of memory can be consumed by the events generated for the huge or
unlimited queues if there is either no or slow listener.  This can cause
system level memory pressure or OOMs.  So, it's better to account the
fsnotify kmem caches to the memcg of the listener.

However the listener can be in a different memcg than the memcg of the
producer and these allocations happen in the context of the event
producer.  This patch introduces remote memcg charging API which the
producer can use to charge the allocations to the memcg of the listener.

There are seven fsnotify kmem caches and among them allocations from
dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and
inotify_inode_mark_cachep happens in the context of syscall from the
listener.  So, SLAB_ACCOUNT is enough for these caches.

The objects from fsnotify_mark_connector_cachep are not accounted as
they are small compared to the notification mark or events and it is
unclear whom to account connector to since it is shared by all events
attached to the inode.

The allocations from the event caches happen in the context of the event
producer.  For such caches we will need to remote charge the allocations
to the listener's memcg.  Thus we save the memcg reference in the
fsnotify_group structure of the listener.

This patch has also moved the members of fsnotify_group to keep the size
same, at least for 64 bit build, even with additional member by filling
the holes.

[shakeelb@google.com: use GFP_KERNEL_ACCOUNT rather than open-coding it]
  Link: http://lkml.kernel.org/r/20180702215439.211597-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20180627191250.209150-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-17 16:20:30 -07:00
Linus Torvalds 73ba2fb33c for-4.19/block-20180812
-----BEGIN PGP SIGNATURE-----
 
 iQJEBAABCAAuFiEEwPw5LcreJtl1+l5K99NY+ylx4KYFAltwvasQHGF4Ym9lQGtl
 cm5lbC5kawAKCRD301j7KXHgpv65EACTq5gSLnJBI6ZPr1RAHruVDnjfzO2Veitl
 tUtjm0XfWmnEiwQ3dYvnyhy99xbyaG3900d9BClCTlH6xaUdSiQkDpcKG/R2F36J
 5mZitYukQcpFAQJWF8YKsTTE7JPl4VglCIDqYiC4+C3rOSVi8lrKn2qp4J4MMCFn
 thRg3jCcq7c5s9Eigsop1pXWQSasubkXfk55Krcp4oybKYpYRKXXf74Mj14QAbwJ
 QHN3VisyAUWoBRg7UQZo1Npe2oPk6bbnJypnjf8M0M2EnlvddEkIlHob91sodka8
 6p4APOEu5cbyXOBCAQsw/koff14mb8aEadqeQA68WvXfIdX9ZjfxCX0OoC3sBEXk
 yqJhZ0C980AM13zIBD8ejv4uasGcPca8W+47mE5P8sRiI++5kBsFWDZPCtUBna0X
 2Kh24NsmEya9XRR5vsB84dsIPQ3tLMkxg/IgQRVDaSnfJz0c/+zm54xDyKRaFT4l
 5iERk2WSkm9+8jNfVmWG0edrv6nRAXjpGwFfOCPh6/LCSCi4xQRULYN7sVzsX8ZK
 FRjt24HftBI8mJbh4BtweJvg+ppVe1gAk3IO3HvxAQhv29Hz+uvFYe9kL+3N8LJA
 Qosr9n9O4+wKYizJcDnw+5iPqCHfAwOm9th4pyedR+R7SmNcP3yNC8AbbheNBiF5
 Zolos5H+JA==
 =b9ib
 -----END PGP SIGNATURE-----

Merge tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block

Pull block updates from Jens Axboe:
 "First pull request for this merge window, there will also be a
  followup request with some stragglers.

  This pull request contains:

   - Fix for a thundering heard issue in the wbt block code (Anchal
     Agarwal)

   - A few NVMe pull requests:
      * Improved tracepoints (Keith)
      * Larger inline data support for RDMA (Steve Wise)
      * RDMA setup/teardown fixes (Sagi)
      * Effects log suppor for NVMe target (Chaitanya Kulkarni)
      * Buffered IO suppor for NVMe target (Chaitanya Kulkarni)
      * TP4004 (ANA) support (Christoph)
      * Various NVMe fixes

   - Block io-latency controller support. Much needed support for
     properly containing block devices. (Josef)

   - Series improving how we handle sense information on the stack
     (Kees)

   - Lightnvm fixes and updates/improvements (Mathias/Javier et al)

   - Zoned device support for null_blk (Matias)

   - AIX partition fixes (Mauricio Faria de Oliveira)

   - DIF checksum code made generic (Max Gurtovoy)

   - Add support for discard in iostats (Michael Callahan / Tejun)

   - Set of updates for BFQ (Paolo)

   - Removal of async write support for bsg (Christoph)

   - Bio page dirtying and clone fixups (Christoph)

   - Set of bcache fix/changes (via Coly)

   - Series improving blk-mq queue setup/teardown speed (Ming)

   - Series improving merging performance on blk-mq (Ming)

   - Lots of other fixes and cleanups from a slew of folks"

* tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block: (190 commits)
  blkcg: Make blkg_root_lookup() work for queues in bypass mode
  bcache: fix error setting writeback_rate through sysfs interface
  null_blk: add lock drop/acquire annotation
  Blk-throttle: reduce tail io latency when iops limit is enforced
  block: paride: pd: mark expected switch fall-throughs
  block: Ensure that a request queue is dissociated from the cgroup controller
  block: Introduce blk_exit_queue()
  blkcg: Introduce blkg_root_lookup()
  block: Remove two superfluous #include directives
  blk-mq: count the hctx as active before allocating tag
  block: bvec_nr_vecs() returns value for wrong slab
  bcache: trivial - remove tailing backslash in macro BTREE_FLAG
  bcache: make the pr_err statement used for ENOENT only in sysfs_attatch section
  bcache: set max writeback rate when I/O request is idle
  bcache: add code comments for bset.c
  bcache: fix mistaken comments in request.c
  bcache: fix mistaken code comments in bcache.h
  bcache: add a comment in super.c
  bcache: avoid unncessary cache prefetch bch_btree_node_get()
  bcache: display rate debug parameters to 0 when writeback is not running
  ...
2018-08-14 10:23:25 -07:00
Linus Torvalds de5d1b39ea Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking/atomics update from Thomas Gleixner:
 "The locking, atomics and memory model brains delivered:

   - A larger update to the atomics code which reworks the ordering
     barriers, consolidates the atomic primitives, provides the new
     atomic64_fetch_add_unless() primitive and cleans up the include
     hell.

   - Simplify cmpxchg() instrumentation and add instrumentation for
     xchg() and cmpxchg_double().

   - Updates to the memory model and documentation"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (48 commits)
  locking/atomics: Rework ordering barriers
  locking/atomics: Instrument cmpxchg_double*()
  locking/atomics: Instrument xchg()
  locking/atomics: Simplify cmpxchg() instrumentation
  locking/atomics/x86: Reduce arch_cmpxchg64*() instrumentation
  tools/memory-model: Rename litmus tests to comply to norm7
  tools/memory-model/Documentation: Fix typo, smb->smp
  sched/Documentation: Update wake_up() & co. memory-barrier guarantees
  locking/spinlock, sched/core: Clarify requirements for smp_mb__after_spinlock()
  sched/core: Use smp_mb() in wake_woken_function()
  tools/memory-model: Add informal LKMM documentation to MAINTAINERS
  locking/atomics/Documentation: Describe atomic_set() as a write operation
  tools/memory-model: Make scripts executable
  tools/memory-model: Remove ACCESS_ONCE() from model
  tools/memory-model: Remove ACCESS_ONCE() from recipes
  locking/memory-barriers.txt/kokr: Update Korean translation to fix broken DMA vs. MMIO ordering example
  MAINTAINERS: Add Daniel Lustig as an LKMM reviewer
  tools/memory-model: Fix ISA2+pooncelock+pooncelock+pombonce name
  tools/memory-model: Add litmus test for full multicopy atomicity
  locking/refcount: Always allow checked forms
  ...
2018-08-13 12:23:39 -07:00
Srikar Dronamraju 6e30396767 sched/numa: Remove redundant field
'numa_entry' is a struct list_head defined in task_struct, but never used.

No functional change.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1529514181-9842-2-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-25 11:41:06 +02:00
Eric W. Biederman 6883f81aac pid: Implement PIDTYPE_TGID
Everywhere except in the pid array we distinguish between a tasks pid and
a tasks tgid (thread group id).  Even in the enumeration we want that
distinction sometimes so we have added __PIDTYPE_TGID.  With leader_pid
we almost have an implementation of PIDTYPE_TGID in struct signal_struct.

Add PIDTYPE_TGID as a first class member of the pid_type enumeration and
into the pids array.  Then remove the __PIDTYPE_TGID special case and the
leader_pid in signal_struct.

The net size increase is just an extra pointer added to struct pid and
an extra pair of pointers of an hlist_node added to task_struct.

The effect on code maintenance is the removal of a number of special
cases today and the potential to remove many more special cases as
PIDTYPE_TGID gets used to it's fullest.  The long term potential
is allowing zombie thread group leaders to exit, which will remove
a lot more special cases in the code.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-21 10:43:12 -05:00
Eric W. Biederman 2c4704756c pids: Move the pgrp and session pid pointers from task_struct to signal_struct
To access these fields the code always has to go to group leader so
going to signal struct is no loss and is actually a fundamental simplification.

This saves a little bit of memory by only allocating the pid pointer array
once instead of once for every thread, and even better this removes a
few potential races caused by the fact that group_leader can be changed
by de_thread, while signal_struct can not.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-21 10:43:12 -05:00
Eric W. Biederman 7a36094d61 pids: Compute task_tgid using signal->leader_pid
The cost is the the same and this removes the need
to worry about complications that come from de_thread
and group_leader changing.

__task_pid_nr_ns has been updated to take advantage of this change.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-21 10:43:12 -05:00
Andrea Parri 7696f9910a sched/Documentation: Update wake_up() & co. memory-barrier guarantees
Both the implementation and the users' expectation [1] for the various
wakeup primitives have evolved over time, but the documentation has not
kept up with these changes: brings it into 2018.

[1] http://lkml.kernel.org/r/20180424091510.GB4064@hirez.programming.kicks-ass.net

Also applied feedback from Alan Stern.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Akira Yokosawa <akiyks@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Daniel Lustig <dlustig@nvidia.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jade Alglave <j.alglave@ucl.ac.uk>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Maranget <luc.maranget@inria.fr>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: parri.andrea@gmail.com
Link: http://lkml.kernel.org/r/20180716180605.16115-12-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-17 09:30:34 +02:00
Josef Bacik d09d8df3a2 blkcg: add generic throttling mechanism
Since IO can be issued from literally anywhere it's almost impossible to
do throttling without having some sort of adverse effect somewhere else
in the system because of locking or other dependencies.  The best way to
solve this is to do the throttling when we know we aren't holding any
other kernel resources.  Do this by tracking throttling in a per-blkg
basis, and if we require throttling flag the task that it needs to check
before it returns to user space and possibly sleep there.

This is to address the case where a process is doing work that is
generating IO that can't be throttled, whether that is directly with a
lot of REQ_META IO, or indirectly by allocating so much memory that it
is swamping the disk with REQ_SWAP.  We can't use task_add_work as we
don't want to induce a memory allocation in the IO path, so simply
saving the request queue in the task and flagging it to do the
notify_resume thing achieves the same result without the overhead of a
memory allocation.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:54 -06:00
Peter Zijlstra 1cef1150ef kthread, sched/core: Fix kthread_parkme() (again...)
Gaurav reports that commit:

  85f1abe001 ("kthread, sched/wait: Fix kthread_parkme() completion issue")

isn't working for him. Because of the following race:

> controller Thread                               CPUHP Thread
> takedown_cpu
> kthread_park
> kthread_parkme
> Set KTHREAD_SHOULD_PARK
>                                                 smpboot_thread_fn
>                                                 set Task interruptible
>
>
> wake_up_process
>  if (!(p->state & state))
>                 goto out;
>
>                                                 Kthread_parkme
>                                                 SET TASK_PARKED
>                                                 schedule
>                                                 raw_spin_lock(&rq->lock)
> ttwu_remote
> waiting for __task_rq_lock
>                                                 context_switch
>
>                                                 finish_lock_switch
>
>
>
>                                                 Case TASK_PARKED
>                                                 kthread_park_complete
>
>
> SET Running

Furthermore, Oleg noticed that the whole scheduler TASK_PARKED
handling is buggered because the TASK_DEAD thing is done with
preemption disabled, the current code can still complete early on
preemption :/

So basically revert that earlier fix and go with a variant of the
alternative mentioned in the commit. Promote TASK_PARKED to special
state to avoid the store-store issue on task->state leading to the
WARN in kthread_unpark() -> __kthread_bind().

But in addition, add wait_task_inactive() to kthread_park() to ensure
the task really is PARKED when we return from kthread_park(). This
avoids the whole kthread still gets migrated nonsense -- although it
would be really good to get this done differently.

Reported-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 85f1abe001 ("kthread, sched/wait: Fix kthread_parkme() completion issue")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-03 09:17:30 +02:00
Will Deacon 784e0300fe rseq: Avoid infinite recursion when delivering SIGSEGV
When delivering a signal to a task that is using rseq, we call into
__rseq_handle_notify_resume() so that the registers pushed in the
sigframe are updated to reflect the state of the restartable sequence
(for example, ensuring that the signal returns to the abort handler if
necessary).

However, if the rseq management fails due to an unrecoverable fault when
accessing userspace or certain combinations of RSEQ_CS_* flags, then we
will attempt to deliver a SIGSEGV. This has the potential for infinite
recursion if the rseq code continuously fails on signal delivery.

Avoid this problem by using force_sigsegv() instead of force_sig(), which
is explicitly designed to reset the SEGV handler to SIG_DFL in the case
of a recursive fault. In doing so, remove rseq_signal_deliver() from the
internal rseq API and have an optional struct ksignal * parameter to
rseq_handle_notify_resume() instead.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: peterz@infradead.org
Cc: paulmck@linux.vnet.ibm.com
Cc: boqun.feng@gmail.com
Link: https://lkml.kernel.org/r/1529664307-983-1-git-send-email-will.deacon@arm.com
2018-06-22 19:04:22 +02:00
Mathieu Desnoyers 9a789fcfe8 rseq/cleanup: Do not abort rseq c.s. in child on fork()
Considering that we explicitly forbid system calls in rseq critical
sections, it is not valid to issue a fork or clone system call within a
rseq critical section, so rseq_fork() is not required to restart an
active rseq c.s. in the child process.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ben Maurer <bmaurer@fb.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Lameter <cl@linux.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-api@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Link: https://lore.kernel.org/lkml/20180619133230.4087-4-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-06-21 12:40:13 +02:00
Mark Rutland 0ed557aa81 sched/core / kcov: avoid kcov_area during task switch
During a context switch, we first switch_mm() to the next task's mm,
then switch_to() that new task.  This means that vmalloc'd regions which
had previously been faulted in can transiently disappear in the context
of the prev task.

Functions instrumented by KCOV may try to access a vmalloc'd kcov_area
during this window, and as the fault handling code is instrumented, this
results in a recursive fault.

We must avoid accessing any kcov_area during this window.  We can do so
with a new flag in kcov_mode, set prior to switching the mm, and cleared
once the new task is live.  Since task_struct::kcov_mode isn't always a
specific enum kcov_mode value, this is made an unsigned int.

The manipulation is hidden behind kcov_{prepare,finish}_switch() helpers,
which are empty for !CONFIG_KCOV kernels.

The code uses macros because I can't use static inline functions without a
circular include dependency between <linux/sched.h> and <linux/kcov.h>,
since the definition of task_struct uses things defined in <linux/kcov.h>

Link: http://lkml.kernel.org/r/20180504135535.53744-4-mark.rutland@arm.com
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-15 07:55:24 +09:00
Linus Torvalds 050e9baa9d Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables
The changes to automatically test for working stack protector compiler
support in the Kconfig files removed the special STACKPROTECTOR_AUTO
option that picked the strongest stack protector that the compiler
supported.

That was all a nice cleanup - it makes no sense to have the AUTO case
now that the Kconfig phase can just determine the compiler support
directly.

HOWEVER.

It also meant that doing "make oldconfig" would now _disable_ the strong
stackprotector if you had AUTO enabled, because in a legacy config file,
the sane stack protector configuration would look like

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  # CONFIG_CC_STACKPROTECTOR_NONE is not set
  # CONFIG_CC_STACKPROTECTOR_REGULAR is not set
  # CONFIG_CC_STACKPROTECTOR_STRONG is not set
  CONFIG_CC_STACKPROTECTOR_AUTO=y

and when you ran this through "make oldconfig" with the Kbuild changes,
it would ask you about the regular CONFIG_CC_STACKPROTECTOR (that had
been renamed from CONFIG_CC_STACKPROTECTOR_REGULAR to just
CONFIG_CC_STACKPROTECTOR), but it would think that the STRONG version
used to be disabled (because it was really enabled by AUTO), and would
disable it in the new config, resulting in:

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
  CONFIG_CC_STACKPROTECTOR=y
  # CONFIG_CC_STACKPROTECTOR_STRONG is not set
  CONFIG_CC_HAS_SANE_STACKPROTECTOR=y

That's dangerously subtle - people could suddenly find themselves with
the weaker stack protector setup without even realizing.

The solution here is to just rename not just the old RECULAR stack
protector option, but also the strong one.  This does that by just
removing the CC_ prefix entirely for the user choices, because it really
is not about the compiler support (the compiler support now instead
automatially impacts _visibility_ of the options to users).

This results in "make oldconfig" actually asking the user for their
choice, so that we don't have any silent subtle security model changes.
The end result would generally look like this:

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
  CONFIG_STACKPROTECTOR=y
  CONFIG_STACKPROTECTOR_STRONG=y
  CONFIG_CC_HAS_SANE_STACKPROTECTOR=y

where the "CC_" versions really are about internal compiler
infrastructure, not the user selections.

Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-14 12:21:18 +09:00
Linus Torvalds b357bf6023 Small update for KVM.
* ARM: lazy context-switching of FPSIMD registers on arm64, "split"
 regions for vGIC redistributor
 
 * s390: cleanups for nested, clock handling, crypto, storage keys and
 control register bits
 
 * x86: many bugfixes, implement more Hyper-V super powers,
 implement lapic_timer_advance_ns even when the LAPIC timer
 is emulated using the processor's VMX preemption timer.  Two
 security-related bugfixes at the top of the branch.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2.0.22 (GNU/Linux)
 
 iQEcBAABAgAGBQJbH8Z/AAoJEL/70l94x66DF+UIAJeOuTp6LGasT/9uAb2OovaN
 +5kGmOPGFwkTcmg8BQHI2fXT4vhxMXWPFcQnyig9eXJVxhuwluXDOH4P9IMay0yw
 VDCBsWRdMvZDQad2hn6Z5zR4Jx01XrSaG/KqvXbbDKDCy96mWG7SYAY2m3ZwmeQi
 3Pa3O3BTijr7hBYnMhdXGkSn4ZyU8uPaAgIJ8795YKeOJ2JmioGYk6fj6y2WCxA3
 ztJymBjTmIoZ/F8bjuVouIyP64xH4q9roAyw4rpu7vnbWGqx1fjPYJoB8yddluWF
 JqCPsPzhKDO7mjZJy+lfaxIlzz2BN7tKBNCm88s5GefGXgZwk3ByAq/0GQ2M3rk=
 =H5zI
 -----END PGP SIGNATURE-----

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM updates from Paolo Bonzini:
 "Small update for KVM:

  ARM:
   - lazy context-switching of FPSIMD registers on arm64
   - "split" regions for vGIC redistributor

  s390:
   - cleanups for nested
   - clock handling
   - crypto
   - storage keys
   - control register bits

  x86:
   - many bugfixes
   - implement more Hyper-V super powers
   - implement lapic_timer_advance_ns even when the LAPIC timer is
     emulated using the processor's VMX preemption timer.
   - two security-related bugfixes at the top of the branch"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (79 commits)
  kvm: fix typo in flag name
  kvm: x86: use correct privilege level for sgdt/sidt/fxsave/fxrstor access
  KVM: x86: pass kvm_vcpu to kvm_read_guest_virt and kvm_write_guest_virt_system
  KVM: x86: introduce linear_{read,write}_system
  kvm: nVMX: Enforce cpl=0 for VMX instructions
  kvm: nVMX: Add support for "VMWRITE to any supported field"
  kvm: nVMX: Restrict VMX capability MSR changes
  KVM: VMX: Optimize tscdeadline timer latency
  KVM: docs: nVMX: Remove known limitations as they do not exist now
  KVM: docs: mmu: KVM support exposing SLAT to guests
  kvm: no need to check return value of debugfs_create functions
  kvm: Make VM ioctl do valloc for some archs
  kvm: Change return type to vm_fault_t
  KVM: docs: mmu: Fix link to NPT presentation from KVM Forum 2008
  kvm: x86: Amend the KVM_GET_SUPPORTED_CPUID API documentation
  KVM: x86: hyperv: declare KVM_CAP_HYPERV_TLBFLUSH capability
  KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX implementation
  KVM: x86: hyperv: simplistic HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE} implementation
  KVM: introduce kvm_make_vcpus_request_mask() API
  KVM: x86: hyperv: do rep check for each hypercall separately
  ...
2018-06-12 11:34:04 -07:00
Mathieu Desnoyers d7822b1e24 rseq: Introduce restartable sequences system call
Expose a new system call allowing each thread to register one userspace
memory area to be used as an ABI between kernel and user-space for two
purposes: user-space restartable sequences and quick access to read the
current CPU number value from user-space.

* Restartable sequences (per-cpu atomics)

Restartables sequences allow user-space to perform update operations on
per-cpu data without requiring heavy-weight atomic operations.

The restartable critical sections (percpu atomics) work has been started
by Paul Turner and Andrew Hunter. It lets the kernel handle restart of
critical sections. [1] [2] The re-implementation proposed here brings a
few simplifications to the ABI which facilitates porting to other
architectures and speeds up the user-space fast path.

Here are benchmarks of various rseq use-cases.

Test hardware:

arm32: ARMv7 Processor rev 4 (v7l) "Cubietruck", 2-core
x86-64: Intel E5-2630 v3@2.40GHz, 16-core, hyperthreading

The following benchmarks were all performed on a single thread.

* Per-CPU statistic counter increment

                getcpu+atomic (ns/op)    rseq (ns/op)    speedup
arm32:                344.0                 31.4          11.0
x86-64:                15.3                  2.0           7.7

* LTTng-UST: write event 32-bit header, 32-bit payload into tracer
             per-cpu buffer

                getcpu+atomic (ns/op)    rseq (ns/op)    speedup
arm32:               2502.0                 2250.0         1.1
x86-64:               117.4                   98.0         1.2

* liburcu percpu: lock-unlock pair, dereference, read/compare word

                getcpu+atomic (ns/op)    rseq (ns/op)    speedup
arm32:                751.0                 128.5          5.8
x86-64:                53.4                  28.6          1.9

* jemalloc memory allocator adapted to use rseq

Using rseq with per-cpu memory pools in jemalloc at Facebook (based on
rseq 2016 implementation):

The production workload response-time has 1-2% gain avg. latency, and
the P99 overall latency drops by 2-3%.

* Reading the current CPU number

Speeding up reading the current CPU number on which the caller thread is
running is done by keeping the current CPU number up do date within the
cpu_id field of the memory area registered by the thread. This is done
by making scheduler preemption set the TIF_NOTIFY_RESUME flag on the
current thread. Upon return to user-space, a notify-resume handler
updates the current CPU value within the registered user-space memory
area. User-space can then read the current CPU number directly from
memory.

Keeping the current cpu id in a memory area shared between kernel and
user-space is an improvement over current mechanisms available to read
the current CPU number, which has the following benefits over
alternative approaches:

- 35x speedup on ARM vs system call through glibc
- 20x speedup on x86 compared to calling glibc, which calls vdso
  executing a "lsl" instruction,
- 14x speedup on x86 compared to inlined "lsl" instruction,
- Unlike vdso approaches, this cpu_id value can be read from an inline
  assembly, which makes it a useful building block for restartable
  sequences.
- The approach of reading the cpu id through memory mapping shared
  between kernel and user-space is portable (e.g. ARM), which is not the
  case for the lsl-based x86 vdso.

On x86, yet another possible approach would be to use the gs segment
selector to point to user-space per-cpu data. This approach performs
similarly to the cpu id cache, but it has two disadvantages: it is
not portable, and it is incompatible with existing applications already
using the gs segment selector for other purposes.

Benchmarking various approaches for reading the current CPU number:

ARMv7 Processor rev 4 (v7l)
Machine model: Cubietruck
- Baseline (empty loop):                                    8.4 ns
- Read CPU from rseq cpu_id:                               16.7 ns
- Read CPU from rseq cpu_id (lazy register):               19.8 ns
- glibc 2.19-0ubuntu6.6 getcpu:                           301.8 ns
- getcpu system call:                                     234.9 ns

x86-64 Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz:
- Baseline (empty loop):                                    0.8 ns
- Read CPU from rseq cpu_id:                                0.8 ns
- Read CPU from rseq cpu_id (lazy register):                0.8 ns
- Read using gs segment selector:                           0.8 ns
- "lsl" inline assembly:                                   13.0 ns
- glibc 2.19-0ubuntu6 getcpu:                              16.6 ns
- getcpu system call:                                      53.9 ns

- Speed (benchmark taken on v8 of patchset)

Running 10 runs of hackbench -l 100000 seems to indicate, contrary to
expectations, that enabling CONFIG_RSEQ slightly accelerates the
scheduler:

Configuration: 2 sockets * 8-core Intel(R) Xeon(R) CPU E5-2630 v3 @
2.40GHz (directly on hardware, hyperthreading disabled in BIOS, energy
saving disabled in BIOS, turboboost disabled in BIOS, cpuidle.off=1
kernel parameter), with a Linux v4.6 defconfig+localyesconfig,
restartable sequences series applied.

* CONFIG_RSEQ=n

avg.:      41.37 s
std.dev.:   0.36 s

* CONFIG_RSEQ=y

avg.:      40.46 s
std.dev.:   0.33 s

- Size

On x86-64, between CONFIG_RSEQ=n/y, the text size increase of vmlinux is
567 bytes, and the data size increase of vmlinux is 5696 bytes.

[1] https://lwn.net/Articles/650333/
[2] http://www.linuxplumbersconf.org/2013/ocw/system/presentations/1695/original/LPC%20-%20PerCpu%20Atomics.pdf

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Chris Lameter <cl@linux.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Andrew Hunter <ahh@google.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Maurer <bmaurer@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-api@vger.kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20151027235635.16059.11630.stgit@pjt-glaptop.roam.corp.google.com
Link: http://lkml.kernel.org/r/20150624222609.6116.86035.stgit@kitami.mtv.corp.google.com
Link: https://lkml.kernel.org/r/20180602124408.8430-3-mathieu.desnoyers@efficios.com
2018-06-06 11:58:31 +02:00
Linus Torvalds f7f4e7fc6c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:

 - power-aware scheduling improvements (Patrick Bellasi)

 - NUMA balancing improvements (Mel Gorman)

 - vCPU scheduling fixes (Rohit Jain)

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Update util_est before updating schedutil
  sched/cpufreq: Modify aggregate utilization to always include blocked FAIR utilization
  sched/deadline/Documentation: Add overrun signal and GRUB-PA documentation
  sched/core: Distinguish between idle_cpu() calls based on desired effect, introduce available_idle_cpu()
  sched/wait: Include <linux/wait.h> in <linux/swait.h>
  sched/numa: Stagger NUMA balancing scan periods for new threads
  sched/core: Don't schedule threads on pre-empted vCPUs
  sched/fair: Avoid calling sync_entity_load_avg() unnecessarily
  sched/fair: Rearrange select_task_rq_fair() to optimize it
2018-06-04 17:45:38 -07:00
Linus Torvalds 4057adafb3 Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:

 - updates to the handling of expedited grace periods

 - updates to reduce lock contention in the rcu_node combining tree

   [ These are in preparation for the consolidation of RCU-bh,
     RCU-preempt, and RCU-sched into a single flavor, which was
     requested by Linus in response to a security flaw whose root cause
     included confusion between the multiple flavors of RCU ]

 - torture-test updates that save their users some time and effort

 - miscellaneous fixes

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
  rcu/x86: Provide early rcu_cpu_starting() callback
  torture: Make kvm-find-errors.sh find build warnings
  rcutorture: Abbreviate kvm.sh summary lines
  rcutorture: Print end-of-test state in kvm.sh summary
  rcutorture: Print end-of-test state
  torture: Fold parse-torture.sh into parse-console.sh
  torture: Add a script to edit output from failed runs
  rcu: Update list of rcu_future_grace_period() trace events
  rcu: Drop early GP request check from rcu_gp_kthread()
  rcu: Simplify and inline cpu_needs_another_gp()
  rcu: The rcu_gp_cleanup() function does not need cpu_needs_another_gp()
  rcu: Make rcu_start_this_gp() check for out-of-range requests
  rcu: Add funnel locking to rcu_start_this_gp()
  rcu: Make rcu_start_future_gp() caller select grace period
  rcu: Inline rcu_start_gp_advanced() into rcu_start_future_gp()
  rcu: Clear request other than RCU_GP_FLAG_INIT at GP end
  rcu: Cleanup, don't put ->completed into an int
  rcu: Switch __rcu_process_callbacks() to rcu_accelerate_cbs()
  rcu: Avoid __call_rcu_core() root rcu_node ->lock acquisition
  rcu: Make rcu_migrate_callbacks wake GP kthread when needed
  ...
2018-06-04 15:54:04 -07:00
Paolo Bonzini 5eec43a1fa KVM/ARM updates for 4.18
- Lazy context-switching of FPSIMD registers on arm64
 - Allow virtual redistributors to be part of two or more MMIO ranges
 -----BEGIN PGP SIGNATURE-----
 
 iQJJBAABCAAzFiEEn9UcU+C1Yxj9lZw9I9DQutE9ekMFAlsRY14VHG1hcmMuenlu
 Z2llckBhcm0uY29tAAoJECPQ0LrRPXpDMGwP/A3FDrzGSjgC65m037/dsQj/Eniv
 NkpueEVO3Z8UN44j0TNdeUzj6vQD376GVDwnW3mFlQ416A4ZwwHkk8cQhbpP2UvQ
 EqKKUgujvLueZeuAwYG/DtrR9VZ6fh7QLD7Mv8DW/0AaNdBN2LyHEkW0qx7cSXqu
 PijTsImj9B8TSykYc0SlJz7Q7Y5QUOYbWrJqqa1cskOdmpN2ATInnA2haXeO7j8v
 lkb+WZ9R6xiJSzMCeLEzFV6tUvTiaSw5lVL64jpJhbkBNWPIVAza0erm9TSlQaTw
 d3uJlAy0W9UkXSSqvbmtXvBFqCyEOzZ0hwi2MF6RoVuFt1yXwLgHGps6OUkho4Kq
 pXWImaRHwxyQGrOY0qm0cxr+6TjYnjn8rIOzmzBOrKKq+aCIQ+Sl+CtNYzczQYeE
 rOFBQFsMlzSRJWyabUjhBGFNfDmZZaVFKnUekEqXXETtLxzLZtx+W9i4tzoA1stv
 y0+4yAjEyOQoRsAAE3GmzpDsu7Eu2sae6+lTo7DX1y+A7Wi94HKmy47sVjrS+evV
 2SLyVZ4mhwMzaQ7ngrjHLD1GXDlBxxk2X+NSmBVe5z4AsuWeoqy81f0rgjyCQNxo
 swEqs0k7mMDo8GQNjawwzhdDuHYm4gTX5iGs/Nxx6K4OoJ0bgv83yb/goArp+LEU
 /QWT4T37A/pEEECe
 =DUmC
 -----END PGP SIGNATURE-----

Merge tag 'kvmarm-for-v4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/ARM updates for 4.18

- Lazy context-switching of FPSIMD registers on arm64
- Allow virtual redistributors to be part of two or more MMIO ranges
2018-06-01 19:17:22 +02:00
Dave Martin 93ee37c2a6 thread_info: Add update_thread_flag() helpers
There are a number of bits of code sprinkled around the kernel to
set a thread flag if a certain condition is true, and clear it
otherwise.

To help make those call sites terser and less cumbersome, this
patch adds a new family of thread flag manipulators

	update*_thread_flag([...,] flag, cond)

which do the equivalent of:

	if (cond)
		set*_thread_flag([...,] flag);
	else
		clear*_thread_flag([...,] flag);

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-05-25 12:27:53 +01:00
Ingo Molnar 0548dc5cde Merge branch 'sched/urgent' into sched/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-25 08:04:39 +02:00
Linus Torvalds 3b78ce4a34 Merge branch 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Merge speculative store buffer bypass fixes from Thomas Gleixner:

 - rework of the SPEC_CTRL MSR management to accomodate the new fancy
   SSBD (Speculative Store Bypass Disable) bit handling.

 - the CPU bug and sysfs infrastructure for the exciting new Speculative
   Store Bypass 'feature'.

 - support for disabling SSB via LS_CFG MSR on AMD CPUs including
   Hyperthread synchronization on ZEN.

 - PRCTL support for dynamic runtime control of SSB

 - SECCOMP integration to automatically disable SSB for sandboxed
   processes with a filter flag for opt-out.

 - KVM integration to allow guests fiddling with SSBD including the new
   software MSR VIRT_SPEC_CTRL to handle the LS_CFG based oddities on
   AMD.

 - BPF protection against SSB

.. this is just the core and x86 side, other architecture support will
come separately.

* 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (49 commits)
  bpf: Prevent memory disambiguation attack
  x86/bugs: Rename SSBD_NO to SSB_NO
  KVM: SVM: Implement VIRT_SPEC_CTRL support for SSBD
  x86/speculation, KVM: Implement support for VIRT_SPEC_CTRL/LS_CFG
  x86/bugs: Rework spec_ctrl base and mask logic
  x86/bugs: Remove x86_spec_ctrl_set()
  x86/bugs: Expose x86_spec_ctrl_base directly
  x86/bugs: Unify x86_spec_ctrl_{set_guest,restore_host}
  x86/speculation: Rework speculative_store_bypass_update()
  x86/speculation: Add virtualized speculative store bypass disable support
  x86/bugs, KVM: Extend speculation control for VIRT_SPEC_CTRL
  x86/speculation: Handle HT correctly on AMD
  x86/cpufeatures: Add FEATURE_ZEN
  x86/cpufeatures: Disentangle SSBD enumeration
  x86/cpufeatures: Disentangle MSR_SPEC_CTRL enumeration from IBRS
  x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP
  KVM: SVM: Move spec control call after restore of GS
  x86/cpu: Make alternative_msr_write work for 32-bit code
  x86/bugs: Fix the parameters alignment and missing void
  x86/bugs: Make cpu_show_common() static
  ...
2018-05-21 11:23:26 -07:00
Ingo Molnar 13a553199f Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
- Updates to the handling of expedited grace periods, perhaps most
   notably parallelizing their initialization.  Other changes
   include fixes from Boqun Feng.

 - Miscellaneous fixes.  These include an nvme fix from Nitzan Carmi
   that I am carrying because it depends on a new SRCU function
   cleanup_srcu_struct_quiesced().  This branch also includes fixes
   from Byungchul Park and Yury Norov.

 - Updates to reduce lock contention in the rcu_node combining tree.
   These are in preparation for the consolidation of RCU-bh,
   RCU-preempt, and RCU-sched into a single flavor, which was
   requested by Linus Torvalds in response to a security flaw
   whose root cause included confusion between the multiple flavors
   of RCU.

 - Torture-test updates that save their users some time and effort.

Conflicts:
	drivers/nvme/host/core.c

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-16 09:34:51 +02:00
Paul E. McKenney c3442697c2 softirq: Eliminate unused cond_resched_softirq() macro
The cond_resched_softirq() macro is not used anywhere in mainline, so
this commit simplifies the kernel by eliminating it.

Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Tested-by: Nicholas Piggin <npiggin@gmail.com>
2018-05-15 10:27:35 -07:00
Rohit Jain 943d355d7f sched/core: Distinguish between idle_cpu() calls based on desired effect, introduce available_idle_cpu()
In the following commit:

  247f2f6f3c ("sched/core: Don't schedule threads on pre-empted vCPUs")

... we distinguish between idle_cpu() when the vCPU is not running for
scheduling threads.

However, the idle_cpu() function is used in other places for
actually checking whether the state of the CPU is idle or not.

Hence split the use of that function based on the desired return value,
by introducing the available_idle_cpu() function.

This fixes a (slight) regression in that initial vCPU commit, because
some code paths (like the load-balancer) don't care and shouldn't care
if the vCPU is preempted or not, they just want to know if there's any
tasks on the CPU.

Signed-off-by: Rohit Jain <rohit.k.jain@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dhaval.giani@oracle.com
Cc: linux-kernel@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: steven.sistare@oracle.com
Cc: subhra.mazumdar@oracle.com
Link: http://lkml.kernel.org/r/1525883988-10356-1-git-send-email-rohit.k.jain@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-14 09:12:26 +02:00
Thomas Gleixner 356e4bfff2 prctl: Add force disable speculation
For certain use cases it is desired to enforce mitigations so they cannot
be undone afterwards. That's important for loader stubs which want to
prevent a child from disabling the mitigation again. Will also be used for
seccomp(). The extra state preserving of the prctl state for SSB is a
preparatory step for EBPF dymanic speculation control.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-05-05 00:51:43 +02:00
Peter Zijlstra b5bf9a90bb sched/core: Introduce set_special_state()
Gaurav reported a perceived problem with TASK_PARKED, which turned out
to be a broken wait-loop pattern in __kthread_parkme(), but the
reported issue can (and does) in fact happen for states that do not do
condition based sleeps.

When the 'current->state = TASK_RUNNING' store of a previous
(concurrent) try_to_wake_up() collides with the setting of a 'special'
sleep state, we can loose the sleep state.

Normal condition based wait-loops are immune to this problem, but for
sleep states that are not condition based are subject to this problem.

There already is a fix for TASK_DEAD. Abstract that and also apply it
to TASK_STOPPED and TASK_TRACED, both of which are also without
condition based wait-loop.

Reported-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-04 07:54:54 +02:00
Peter Zijlstra 317d359df9 sched/core: Force proper alignment of 'struct util_est'
For some as yet not understood reason, Tony gets unaligned access
traps on IA64 because of:

  struct util_est ue = READ_ONCE(p->se.avg.util_est);

and:

  WRITE_ONCE(p->se.avg.util_est, ue);

introduced by commit:

  d519329f72 ("sched/fair: Update util_est only on util_avg updates")

Normally those two fields should end up on an 8-byte aligned location,
but UP and RANDSTRUCT can mess that up so enforce the alignment
explicitly.

Also make the alignment on sched_avg unconditional, as it is really
about data locality, not false-sharing.

With or without this patch the layout for sched_avg on a
ia64-defconfig build looks like:

	$ pahole -EC sched_avg ia64-defconfig/kernel/sched/core.o
	die__process_function: tag not supported (INVALID)!
	struct sched_avg {
		/* typedef u64 */ long long unsigned int     last_update_time;                   /*     0     8 */
		/* typedef u64 */ long long unsigned int     load_sum;                           /*     8     8 */
		/* typedef u64 */ long long unsigned int     runnable_load_sum;                  /*    16     8 */
		/* typedef u32 */ unsigned int               util_sum;                           /*    24     4 */
		/* typedef u32 */ unsigned int               period_contrib;                     /*    28     4 */
		long unsigned int          load_avg;                                             /*    32     8 */
		long unsigned int          runnable_load_avg;                                    /*    40     8 */
		long unsigned int          util_avg;                                             /*    48     8 */
		struct util_est {
			unsigned int       enqueued;                                             /*    56     4 */
			unsigned int       ewma;                                                 /*    60     4 */
		} util_est; /*    56     8 */
		/* --- cacheline 1 boundary (64 bytes) --- */

		/* size: 64, cachelines: 1, members: 9 */
	};

Reported-and-Tested-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Norbert Manthey <nmanthey@amazon.de>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony <tony.luck@intel.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Fixes: d519329f72 ("sched/fair: Update util_est only on util_avg updates")
Link: http://lkml.kernel.org/r/20180405080521.GG4129@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-04-05 10:56:16 +02:00
Patrick Bellasi 7f65ea42eb sched/fair: Add util_est on top of PELT
The util_avg signal computed by PELT is too variable for some use-cases.
For example, a big task waking up after a long sleep period will have its
utilization almost completely decayed. This introduces some latency before
schedutil will be able to pick the best frequency to run a task.

The same issue can affect task placement. Indeed, since the task
utilization is already decayed at wakeup, when the task is enqueued in a
CPU, this can result in a CPU running a big task as being temporarily
represented as being almost empty. This leads to a race condition where
other tasks can be potentially allocated on a CPU which just started to run
a big task which slept for a relatively long period.

Moreover, the PELT utilization of a task can be updated every [ms], thus
making it a continuously changing value for certain longer running
tasks. This means that the instantaneous PELT utilization of a RUNNING
task is not really meaningful to properly support scheduler decisions.

For all these reasons, a more stable signal can do a better job of
representing the expected/estimated utilization of a task/cfs_rq.
Such a signal can be easily created on top of PELT by still using it as
an estimator which produces values to be aggregated on meaningful
events.

This patch adds a simple implementation of util_est, a new signal built on
top of PELT's util_avg where:

    util_est(task) = max(task::util_avg, f(task::util_avg@dequeue))

This allows to remember how big a task has been reported by PELT in its
previous activations via f(task::util_avg@dequeue), which is the new
_task_util_est(struct task_struct*) function added by this patch.

If a task should change its behavior and it runs longer in a new
activation, after a certain time its util_est will just track the
original PELT signal (i.e. task::util_avg).

The estimated utilization of cfs_rq is defined only for root ones.
That's because the only sensible consumer of this signal are the
scheduler and schedutil when looking for the overall CPU utilization
due to FAIR tasks.

For this reason, the estimated utilization of a root cfs_rq is simply
defined as:

    util_est(cfs_rq) = max(cfs_rq::util_avg, cfs_rq::util_est::enqueued)

where:

    cfs_rq::util_est::enqueued = sum(_task_util_est(task))
                                 for each RUNNABLE task on that root cfs_rq

It's worth noting that the estimated utilization is tracked only for
objects of interests, specifically:

 - Tasks: to better support tasks placement decisions
 - root cfs_rqs: to better support both tasks placement decisions as
                 well as frequencies selection

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@android.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20180309095245.11071-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-20 08:11:06 +01:00
Peter Zijlstra 9e49e2447c sched/core: Remove TASK_ALL
It's unused:

  $ git grep "\<TASK_ALL\>" | wc -l
  1

... and it is also dangerous, kill the bugger.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180227160510.10829-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-12 10:51:47 +01:00
Linus Torvalds a2e5790d84 Merge branch 'akpm' (patches from Andrew)
Merge misc updates from Andrew Morton:

 - kasan updates

 - procfs

 - lib/bitmap updates

 - other lib/ updates

 - checkpatch tweaks

 - rapidio

 - ubsan

 - pipe fixes and cleanups

 - lots of other misc bits

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (114 commits)
  Documentation/sysctl/user.txt: fix typo
  MAINTAINERS: update ARM/QUALCOMM SUPPORT patterns
  MAINTAINERS: update various PALM patterns
  MAINTAINERS: update "ARM/OXNAS platform support" patterns
  MAINTAINERS: update Cortina/Gemini patterns
  MAINTAINERS: remove ARM/CLKDEV SUPPORT file pattern
  MAINTAINERS: remove ANDROID ION pattern
  mm: docs: add blank lines to silence sphinx "Unexpected indentation" errors
  mm: docs: fix parameter names mismatch
  mm: docs: fixup punctuation
  pipe: read buffer limits atomically
  pipe: simplify round_pipe_size()
  pipe: reject F_SETPIPE_SZ with size over UINT_MAX
  pipe: fix off-by-one error when checking buffer limits
  pipe: actually allow root to exceed the pipe buffer limits
  pipe, sysctl: remove pipe_proc_fn()
  pipe, sysctl: drop 'min' parameter from pipe-max-size converter
  kasan: rework Kconfig settings
  crash_dump: is_kdump_kernel can be boolean
  kernel/mutex: mutex_is_locked can be boolean
  ...
2018-02-06 22:15:42 -08:00
Mike Rapoport 2ee0826085 pids: introduce find_get_task_by_vpid() helper
There are several functions that do find_task_by_vpid() followed by
get_task_struct().  We can use a helper function instead.

Link: http://lkml.kernel.org/r/1509602027-11337-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06 18:32:46 -08:00
Mel Gorman 32e839dda3 sched/fair: Use a recently used CPU as an idle candidate and the basis for SIS
The select_idle_sibling() (SIS) rewrite in commit:

  10e2f1acd0 ("sched/core: Rewrite and improve select_idle_siblings()")

... replaced a domain iteration with a search that broadly speaking
does a wrapped walk of the scheduler domain sharing a last-level-cache.

While this had a number of improvements, one consequence is that two tasks
that share a waker/wakee relationship push each other around a socket. Even
though two tasks may be active, all cores are evenly used. This is great from
a search perspective and spreads a load across individual cores, but it has
adverse consequences for cpufreq. As each CPU has relatively low utilisation,
cpufreq may decide the utilisation is too low to used a higher P-state and
overall computation throughput suffers.

While individual cpufreq and cpuidle drivers may compensate by artifically
boosting P-state (at c0) or avoiding lower C-states (during idle), it does
not help if hardware-based cpufreq (e.g. HWP) is used.

This patch tracks a recently used CPU based on what CPU a task was running
on when it last was a waker a CPU it was recently using when a task is a
wakee. During SIS, the recently used CPU is used as a target if it's still
allowed by the task and is idle.

The benefit may be non-obvious so consider an example of two tasks
communicating back and forth. Task A may be an application doing IO where
task B is a kworker or kthread like journald. Task A may issue IO, wake
B and B wakes up A on completion.  With the existing scheme this may look
like the following (potentially different IDs if SMT is in use but similar
principal applies).

 A (cpu 0)	wake	B (wakes on cpu 1)
 B (cpu 1)	wake	A (wakes on cpu 2)
 A (cpu 2)	wake	B (wakes on cpu 3)
 etc.

A careful reader may wonder why CPU 0 was not idle when B wakes A the
first time and it's simply due to the fact that A can be rescheduled to
another CPU and the pattern is that prev == target when B tries to wakeup A
and the information about CPU 0 has been lost.

With this patch, the pattern is more likely to be:

 A (cpu 0)	wake	B (wakes on cpu 1)
 B (cpu 1)	wake	A (wakes on cpu 0)
 A (cpu 0)	wake	B (wakes on cpu 1)
 etc

i.e. two communicating casts are more likely to use just two cores instead
of all available cores sharing a LLC.

The most dramatic speedup was noticed on dbench using the XFS filesystem on
UMA as clients interact heavily with workqueues in that configuration. Note
that a similar speedup is not observed on ext4 as the wakeup pattern
is different:

                          4.15.0-rc9             4.15.0-rc9
                           waprev-v1        biasancestor-v1
 Hmean      1      287.54 (   0.00%)      817.01 ( 184.14%)
 Hmean      2     1268.12 (   0.00%)     1781.24 (  40.46%)
 Hmean      4     1739.68 (   0.00%)     1594.47 (  -8.35%)
 Hmean      8     2464.12 (   0.00%)     2479.56 (   0.63%)
 Hmean     64     1455.57 (   0.00%)     1434.68 (  -1.44%)

The results can be less dramatic on NUMA where automatic balancing interferes
with the test. It's also known that network benchmarks running on localhost
also benefit quite a bit from this patch (roughly 10% on netperf RR for UDP
and TCP depending on the machine). Hackbench also seens small improvements
(6-11% depending on machine and thread count). The facebook schbench was also
tested but in most cases showed little or no different to wakeup latencies.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180130104555.4125-5-mgorman@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-06 10:20:37 +01:00
Linus Torvalds af8c5e2d60 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Implement frequency/CPU invariance and OPP selection for
     SCHED_DEADLINE (Juri Lelli)

   - Tweak the task migration logic for better multi-tasking
     workload scalability (Mel Gorman)

   - Misc cleanups, fixes and improvements"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/deadline: Make bandwidth enforcement scale-invariant
  sched/cpufreq: Move arch_scale_{freq,cpu}_capacity() outside of #ifdef CONFIG_SMP
  sched/cpufreq: Remove arch_scale_freq_capacity()'s 'sd' parameter
  sched/cpufreq: Always consider all CPUs when deciding next freq
  sched/cpufreq: Split utilization signals
  sched/cpufreq: Change the worker kthread to SCHED_DEADLINE
  sched/deadline: Move CPU frequency selection triggering points
  sched/cpufreq: Use the DEADLINE utilization signal
  sched/deadline: Implement "runtime overrun signal" support
  sched/fair: Only immediately migrate tasks due to interrupts if prev and target CPUs share cache
  sched/fair: Correct obsolete comment about cpufreq_update_util()
  sched/fair: Remove impossible condition from find_idlest_group_cpu()
  sched/cpufreq: Don't pass flags to sugov_set_iowait_boost()
  sched/cpufreq: Initialize sg_cpu->flags to 0
  sched/fair: Consider RT/IRQ pressure in capacity_spare_wake()
  sched/fair: Use 'unsigned long' for utilization, consistently
  sched/core: Rework and clarify prepare_lock_switch()
  sched/fair: Remove unused 'curr' parameter from wakeup_gran
  sched/headers: Constify object_is_on_stack()
2018-01-30 11:55:56 -08:00
Juri Lelli 794a56ebd9 sched/cpufreq: Change the worker kthread to SCHED_DEADLINE
Worker kthread needs to be able to change frequency for all other
threads.

Make it special, just under STOP class.

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: alessio.balsini@arm.com
Cc: bristot@redhat.com
Cc: dietmar.eggemann@arm.com
Cc: joelaf@google.com
Cc: juri.lelli@redhat.com
Cc: mathieu.poirier@linaro.org
Cc: morten.rasmussen@arm.com
Cc: patrick.bellasi@arm.com
Cc: rjw@rjwysocki.net
Cc: rostedt@goodmis.org
Cc: tkjos@android.com
Cc: tommaso.cucinotta@santannapisa.it
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/20171204102325.5110-4-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-01-10 12:53:29 +01:00
Juri Lelli 34be39305a sched/deadline: Implement "runtime overrun signal" support
This patch adds the possibility of getting the delivery of a SIGXCPU
signal whenever there is a runtime overrun. The request is done through
the sched_flags field within the sched_attr structure.

Forward port of https://lkml.org/lkml/2009/10/16/170

Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1513077024-25461-1-git-send-email-claudio@evidence.eu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-01-10 11:30:31 +01:00
David Howells 0500871f21 Construct init thread stack in the linker script rather than by union
Construct the init thread stack in the linker script rather than doing it
by means of a union so that ia64's init_task.c can be got rid of.

The following symbols are then made available from INIT_TASK_DATA() linker
script macro:

	init_thread_union
	init_stack

INIT_TASK_DATA() also expands the region to THREAD_SIZE to accommodate the
size of the init stack.  init_thread_union is given its own section so that
it can be placed into the stack space in the right order.  I'm assuming
that the ia64 ordering is correct and that the task_struct is first and the
thread_info second.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Tested-by: Will Deacon <will.deacon@arm.com> (arm64)
Tested-by: Palmer Dabbelt <palmer@sifive.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
2018-01-09 23:21:02 +00:00
Linus Torvalds 1f76a75561 Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar:
 "Misc fixes:

   - Fix a S390 boot hang that was caused by the lock-break logic.
     Remove lock-break to begin with, as review suggested it was
     unreasonably fragile and our confidence in its continued good
     health is lower than our confidence in its removal.

   - Remove the lockdep cross-release checking code for now, because of
     unresolved false positive warnings. This should make lockdep work
     well everywhere again.

   - Get rid of the final (and single) ACCESS_ONCE() straggler and
     remove the API from v4.15.

   - Fix a liblockdep build warning"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tools/lib/lockdep: Add missing declaration of 'pr_cont()'
  checkpatch: Remove ACCESS_ONCE() warning
  compiler.h: Remove ACCESS_ONCE()
  tools/include: Remove ACCESS_ONCE()
  tools/perf: Convert ACCESS_ONCE() to READ_ONCE()
  locking/lockdep: Remove the cross-release locking checks
  locking/core: Remove break_lock field when CONFIG_GENERIC_LOCKBREAK=y
  locking/core: Fix deadlock during boot on systems with GENERIC_LOCKBREAK
2017-12-15 11:44:59 -08:00
Arnd Bergmann 3756f6401c exec: avoid gcc-8 warning for get_task_comm
gcc-8 warns about using strncpy() with the source size as the limit:

  fs/exec.c:1223:32: error: argument to 'sizeof' in 'strncpy' call is the same expression as the source; did you mean to use the size of the destination? [-Werror=sizeof-pointer-memaccess]

This is indeed slightly suspicious, as it protects us from source
arguments without NUL-termination, but does not guarantee that the
destination is terminated.

This keeps the strncpy() to ensure we have properly padded target
buffer, but ensures that we use the correct length, by passing the
actual length of the destination buffer as well as adding a build-time
check to ensure it is exactly TASK_COMM_LEN.

There are only 23 callsites which I all reviewed to ensure this is
currently the case.  We could get away with doing only the check or
passing the right length, but it doesn't hurt to do both.

Link: http://lkml.kernel.org/r/20171205151724.1764896-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Kees Cook <keescook@chromium.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Aleksa Sarai <asarai@suse.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-12-14 16:00:48 -08:00
Ingo Molnar e966eaeeb6 locking/lockdep: Remove the cross-release locking checks
This code (CONFIG_LOCKDEP_CROSSRELEASE=y and CONFIG_LOCKDEP_COMPLETIONS=y),
while it found a number of old bugs initially, was also causing too many
false positives that caused people to disable lockdep - which is arguably
a worse overall outcome.

If we disable cross-release by default but keep the code upstream then
in practice the most likely outcome is that we'll allow the situation
to degrade gradually, by allowing entropy to introduce more and more
false positives, until it overwhelms maintenance capacity.

Another bad side effect was that people were trying to work around
the false positives by uglifying/complicating unrelated code. There's
a marked difference between annotating locking operations and
uglifying good code just due to bad lock debugging code ...

This gradual decrease in quality happened to a number of debugging
facilities in the kernel, and lockdep is pretty complex already,
so we cannot risk this outcome.

Either cross-release checking can be done right with no false positives,
or it should not be included in the upstream kernel.

( Note that it might make sense to maintain it out of tree and go through
  the false positives every now and then and see whether new bugs were
  introduced. )

Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-12 12:38:51 +01:00
Dan Carpenter aa5222e92f sched/deadline: Don't use dubious signed bitfields
It doesn't cause a run-time bug, but these bitfields should be unsigned.
When it's signed ->dl_throttled is set to either 0 or -1, instead of
0 and 1 as expected.

The sched.h file is included into tons of places so Sparse generates
a flood of warnings like this:

  ./include/linux/sched.h:477:54: error: dubious one-bit signed bitfield

Reported-by: Matthew Wilcox <willy@infradead.org>
Reported-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-janitors@vger.kernel.org
Cc: luca abeni <luca.abeni@santannapisa.it>
Link: http://lkml.kernel.org/r/20171013070121.dzcncojuj2f4utij@mwanda
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-21 09:25:01 +01:00
Ingo Molnar 8a103df440 Merge branch 'linus' into sched/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-08 10:17:15 +01:00
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Frederic Weisbecker edb9382175 sched/isolation: Move isolcpus= handling to the housekeeping code
We want to centralize the isolation features, to be done by the housekeeping
subsystem and scheduler domain isolation is a significant part of it.

No intended behaviour change, we just reuse the housekeeping cpumask
and core code.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-11-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-27 09:55:30 +02:00
luca abeni 799ba82de0 sched/deadline: Use C bitfields for the state flags
Ask the compiler to use a single bit for storing true / false values,
instead of wasting the size of a whole int value.
Tested with gcc 5.4.0 on x86_64, and the compiler produces the expected
Assembly (similar to the Assembly code generated when explicitly accessing
the bits with bitmasks, "&" and "|").

Signed-off-by: luca abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1504778971-13573-5-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-10 11:45:26 +02:00
Peter Zijlstra 1d48b080bc sched/debug: Rename task-state printing helpers
Steve requested better names for the new task-state helper functions.

So introduce the concept of task-state index for the printing and
rename __get_task_state() to task_state_index() and
__task_state_to_char() to task_index_to_char().

Requested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170929115016.pzlqc7ss3ccystyg@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-10 11:43:29 +02:00
Peter Zijlstra 1ea6c46a23 sched/fair: Propagate an effective runnable_load_avg
The load balancer uses runnable_load_avg as load indicator. For
!cgroup this is:

  runnable_load_avg = \Sum se->avg.load_avg ; where se->on_rq

That is, a direct sum of all runnable tasks on that runqueue. As
opposed to load_avg, which is a sum of all tasks on the runqueue,
which includes a blocked component.

However, in the cgroup case, this comes apart since the group entities
are always runnable, even if most of their constituent entities are
blocked.

Therefore introduce a runnable_weight which for task entities is the
same as the regular weight, but for group entities is a fraction of
the entity weight and represents the runnable part of the group
runqueue.

Then propagate this load through the PELT hierarchy to arrive at an
effective runnable load avgerage -- which we should not confuse with
the canonical runnable load average.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 19:35:15 +02:00
Peter Zijlstra 8ef9925b02 sched/debug: Add explicit TASK_PARKED printing
Currently TASK_PARKED is masqueraded as TASK_INTERRUPTIBLE, give it
its own print state because it will not in fact get woken by regular
wakeups and is a long-term state.

This requires moving TASK_PARKED into the TASK_REPORT mask, and since
that latter needs to be a contiguous bitmask, we need to shuffle the
bits around a bit.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 11:02:57 +02:00
Peter Zijlstra 06eb61844d sched/debug: Add explicit TASK_IDLE printing
Markus reported that kthreads that idle using TASK_IDLE instead of
TASK_INTERRUPTIBLE are reported in as TASK_UNINTERRUPTIBLE and things
like htop mark those red.

This is undesirable, so add an explicit state for TASK_IDLE.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 11:02:56 +02:00
Peter Zijlstra 5f6ad26ea3 sched/tracing: Use common task-state helpers
Remove yet another task-state char instance.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 11:02:45 +02:00
Peter Zijlstra efb40f588b sched/tracing: Fix trace_sched_switch task-state printing
Convert trace_sched_switch to use the common task-state helpers and
fix the "X" and "Z" order, possibly they ended up in the wrong order
because TASK_REPORT has them in the wrong order too.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 10:09:10 +02:00
Peter Zijlstra 92c4bc9f9c sched/debug: Convert TASK_state to hex
Bit patterns are easier in hex.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 10:09:08 +02:00
Peter Zijlstra 1593baab91 sched/debug: Implement consistent task-state printing
Currently get_task_state() and task_state_to_char() report different
states, create a number of common helpers and unify the reported state
space.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-29 10:09:08 +02:00
Davidlohr Bueso a23ba907d5 locking/rtmutex: replace top-waiter and pi_waiters leftmost caching
... with the generic rbtree flavor instead. No changes
in semantics whatsoever.

Link: http://lkml.kernel.org/r/20170719014603.19029-10-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-08 18:26:49 -07:00
Linus Torvalds f57091767a Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cache quality monitoring update from Thomas Gleixner:
 "This update provides a complete rewrite of the Cache Quality
  Monitoring (CQM) facility.

  The existing CQM support was duct taped into perf with a lot of issues
  and the attempts to fix those turned out to be incomplete and
  horrible.

  After lengthy discussions it was decided to integrate the CQM support
  into the Resource Director Technology (RDT) facility, which is the
  obvious choise as in hardware CQM is part of RDT. This allowed to add
  Memory Bandwidth Monitoring support on top.

  As a result the mechanisms for allocating cache/memory bandwidth and
  the corresponding monitoring mechanisms are integrated into a single
  management facility with a consistent user interface"

* 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits)
  x86/intel_rdt: Turn off most RDT features on Skylake
  x86/intel_rdt: Add command line options for resource director technology
  x86/intel_rdt: Move special case code for Haswell to a quirk function
  x86/intel_rdt: Remove redundant ternary operator on return
  x86/intel_rdt/cqm: Improve limbo list processing
  x86/intel_rdt/mbm: Fix MBM overflow handler during CPU hotplug
  x86/intel_rdt: Modify the intel_pqr_state for better performance
  x86/intel_rdt/cqm: Clear the default RMID during hotcpu
  x86/intel_rdt: Show bitmask of shareable resource with other executing units
  x86/intel_rdt/mbm: Handle counter overflow
  x86/intel_rdt/mbm: Add mbm counter initialization
  x86/intel_rdt/mbm: Basic counting of MBM events (total and local)
  x86/intel_rdt/cqm: Add CPU hotplug support
  x86/intel_rdt/cqm: Add sched_in support
  x86/intel_rdt: Introduce rdt_enable_key for scheduling
  x86/intel_rdt/cqm: Add mount,umount support
  x86/intel_rdt/cqm: Add rmdir support
  x86/intel_rdt: Separate the ctrl bits from rmdir
  x86/intel_rdt/cqm: Add mon_data
  x86/intel_rdt: Prepare for RDT monitor data support
  ...
2017-09-04 13:56:37 -07:00
Linus Torvalds 5f82e71a00 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:

 - Add 'cross-release' support to lockdep, which allows APIs like
   completions, where it's not the 'owner' who releases the lock, to be
   tracked. It's all activated automatically under
   CONFIG_PROVE_LOCKING=y.

 - Clean up (restructure) the x86 atomics op implementation to be more
   readable, in preparation of KASAN annotations. (Dmitry Vyukov)

 - Fix static keys (Paolo Bonzini)

 - Add killable versions of down_read() et al (Kirill Tkhai)

 - Rework and fix jump_label locking (Marc Zyngier, Paolo Bonzini)

 - Rework (and fix) tlb_flush_pending() barriers (Peter Zijlstra)

 - Remove smp_mb__before_spinlock() and convert its usages, introduce
   smp_mb__after_spinlock() (Peter Zijlstra)

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (56 commits)
  locking/lockdep/selftests: Fix mixed read-write ABBA tests
  sched/completion: Avoid unnecessary stack allocation for COMPLETION_INITIALIZER_ONSTACK()
  acpi/nfit: Fix COMPLETION_INITIALIZER_ONSTACK() abuse
  locking/pvqspinlock: Relax cmpxchg's to improve performance on some architectures
  smp: Avoid using two cache lines for struct call_single_data
  locking/lockdep: Untangle xhlock history save/restore from task independence
  locking/refcounts, x86/asm: Disable CONFIG_ARCH_HAS_REFCOUNT for the time being
  futex: Remove duplicated code and fix undefined behaviour
  Documentation/locking/atomic: Finish the document...
  locking/lockdep: Fix workqueue crossrelease annotation
  workqueue/lockdep: 'Fix' flush_work() annotation
  locking/lockdep/selftests: Add mixed read-write ABBA tests
  mm, locking/barriers: Clarify tlb_flush_pending() barriers
  locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS truly non-interactive
  locking/lockdep: Explicitly initialize wq_barrier::done::map
  locking/lockdep: Rename CONFIG_LOCKDEP_COMPLETE to CONFIG_LOCKDEP_COMPLETIONS
  locking/lockdep: Reword title of LOCKDEP_CROSSRELEASE config
  locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE part of CONFIG_PROVE_LOCKING
  locking/refcounts, x86/asm: Implement fast refcount overflow protection
  locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease
  ...
2017-09-04 11:52:29 -07:00
Linus Torvalds f213a6c84c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - fix affine wakeups (Peter Zijlstra)

   - improve CPU onlining (and general bootup) scalability on systems
     with ridiculous number (thousands) of CPUs (Peter Zijlstra)

   - sched/numa updates (Rik van Riel)

   - sched/deadline updates (Byungchul Park)

   - sched/cpufreq enhancements and related cleanups (Viresh Kumar)

   - sched/debug enhancements (Xie XiuQi)

   - various fixes"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
  sched/debug: Optimize sched_domain sysctl generation
  sched/topology: Avoid pointless rebuild
  sched/topology, cpuset: Avoid spurious/wrong domain rebuilds
  sched/topology: Improve comments
  sched/topology: Fix memory leak in __sdt_alloc()
  sched/completion: Document that reinit_completion() must be called after complete_all()
  sched/autogroup: Fix error reporting printk text in autogroup_create()
  sched/fair: Fix wake_affine() for !NUMA_BALANCING
  sched/debug: Intruduce task_state_to_char() helper function
  sched/debug: Show task state in /proc/sched_debug
  sched/debug: Use task_pid_nr_ns in /proc/$pid/sched
  sched/core: Remove unnecessary initialization init_idle_bootup_task()
  sched/deadline: Change return value of cpudl_find()
  sched/deadline: Make find_later_rq() choose a closer CPU in topology
  sched/numa: Scale scan period with tasks in group and shared/private
  sched/numa: Slow down scan rate if shared faults dominate
  sched/pelt: Fix false running accounting
  sched: Mark pick_next_task_dl() and build_sched_domain() as static
  sched/cpupri: Don't re-initialize 'struct cpupri'
  sched/deadline: Don't re-initialize 'struct cpudl'
  ...
2017-09-04 09:10:24 -07:00
Linus Torvalds 0081a0ce80 Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnad:
 "The main RCU related changes in this cycle were:

   - Removal of spin_unlock_wait()
   - SRCU updates
   - RCU torture-test updates
   - RCU Documentation updates
   - Extend the sys_membarrier() ABI with the MEMBARRIER_CMD_PRIVATE_EXPEDITED variant
   - Miscellaneous RCU fixes
   - CPU-hotplug fixes"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (63 commits)
  arch: Remove spin_unlock_wait() arch-specific definitions
  locking: Remove spin_unlock_wait() generic definitions
  drivers/ata: Replace spin_unlock_wait() with lock/unlock pair
  ipc: Replace spin_unlock_wait() with lock/unlock pair
  exit: Replace spin_unlock_wait() with lock/unlock pair
  completion: Replace spin_unlock_wait() with lock/unlock pair
  doc: Set down RCU's scheduling-clock-interrupt needs
  doc: No longer allowed to use rcu_dereference on non-pointers
  doc: Add RCU files to docbook-generation files
  doc: Update memory-barriers.txt for read-to-write dependencies
  doc: Update RCU documentation
  membarrier: Provide expedited private command
  rcu: Remove exports from rcu_idle_exit() and rcu_idle_enter()
  rcu: Add warning to rcu_idle_enter() for irqs enabled
  rcu: Make rcu_idle_enter() rely on callers disabling irqs
  rcu: Add assertions verifying blocked-tasks list
  rcu/tracing: Set disable_rcu_irq_enter on rcu_eqs_exit()
  rcu: Add TPS() protection for _rcu_barrier_trace strings
  rcu: Use idle versions of swait to make idle-hack clear
  swait: Add idle variants which don't contribute to load average
  ...
2017-09-04 08:13:52 -07:00
Ingo Molnar 3a9ff4fd04 Merge branch 'linus' into sched/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-25 11:07:13 +02:00
Ingo Molnar 10c9850cb2 Merge branch 'linus' into locking/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-25 11:04:51 +02:00
Oleg Nesterov dd1c1f2f20 pids: make task_tgid_nr_ns() safe
This was reported many times, and this was even mentioned in commit
52ee2dfdd4 ("pids: refactor vnr/nr_ns helpers to make them safe") but
somehow nobody bothered to fix the obvious problem: task_tgid_nr_ns() is
not safe because task->group_leader points to nowhere after the exiting
task passes exit_notify(), rcu_read_lock() can not help.

We really need to change __unhash_process() to nullify group_leader,
parent, and real_parent, but this needs some cleanups.  Until then we
can turn task_tgid_nr_ns() into another user of __task_pid_nr_ns() and
fix the problem.

Reported-by: Troy Kensinger <tkensinger@google.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-21 12:47:31 -07:00
Paul E. McKenney ccdd29ffff rcu: Create reasonable API for do_exit() TASKS_RCU processing
Currently, the exit-time support for TASKS_RCU is open-coded in do_exit().
This commit creates exit_tasks_rcu_start() and exit_tasks_rcu_finish()
APIs for do_exit() use.  This has the benefit of confining the use of the
tasks_rcu_exit_srcu variable to one file, allowing it to become static.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-08-17 07:26:05 -07:00
Byungchul Park 23f873d8f9 locking/lockdep: Detect and handle hist_lock ring buffer overwrite
The ring buffer can be overwritten by hardirq/softirq/work contexts.
That cases must be considered on rollback or commit. For example,

          |<------ hist_lock ring buffer size ----->|
          ppppppppppppiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
wrapped > iiiiiiiiiiiiiiiiiiiiiii....................

          where 'p' represents an acquisition in process context,
          'i' represents an acquisition in irq context.

On irq exit, crossrelease tries to rollback idx to original position,
but it should not because the entry already has been invalid by
overwriting 'i'. Avoid rollback or commit for entries overwritten.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Cc: willy@infradead.org
Link: http://lkml.kernel.org/r/1502089981-21272-7-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 12:29:08 +02:00
Byungchul Park b09be676e0 locking/lockdep: Implement the 'crossrelease' feature
Lockdep is a runtime locking correctness validator that detects and
reports a deadlock or its possibility by checking dependencies between
locks. It's useful since it does not report just an actual deadlock but
also the possibility of a deadlock that has not actually happened yet.
That enables problems to be fixed before they affect real systems.

However, this facility is only applicable to typical locks, such as
spinlocks and mutexes, which are normally released within the context in
which they were acquired. However, synchronization primitives like page
locks or completions, which are allowed to be released in any context,
also create dependencies and can cause a deadlock.

So lockdep should track these locks to do a better job. The 'crossrelease'
implementation makes these primitives also be tracked.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Cc: willy@infradead.org
Link: http://lkml.kernel.org/r/1502089981-21272-6-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 12:29:07 +02:00
Peter Zijlstra d92a8cfcb3 locking/lockdep: Rework FS_RECLAIM annotation
A while ago someone, and I cannot find the email just now, asked if we
could not implement the RECLAIM_FS inversion stuff with a 'fake' lock
like we use for other things like workqueues etc. I think this should
be possible which allows reducing the 'irq' states and will reduce the
amount of __bfs() lookups we do.

Removing the 1 IRQ state results in 4 less __bfs() walks per
dependency, improving lockdep performance. And by moving this
annotation out of the lockdep code it becomes easier for the mm people
to extend.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: iamjoonsoo.kim@lge.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 12:29:03 +02:00
Xie XiuQi 20435d84e5 sched/debug: Intruduce task_state_to_char() helper function
Now that we have more than one place to get the task state,
intruduce the task_state_to_char() helper function to save some code.

No functionality changed.

Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <cj.chengjian@huawei.com>
Cc: <huawei.libin@huawei.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1502095463-160172-3-git-send-email-xiexiuqi@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 12:18:20 +02:00
Vikas Shivappa d6aaba615a x86/intel_rdt/cqm: Add tasks file support
The root directory, ctrl_mon and monitor groups are populated
with a read/write file named "tasks". When read, it shows all the task
IDs assigned to the resource group.

Tasks can be added to groups by writing the PID to the file. A task can
be present in one "ctrl_mon" group "and" one "monitor" group. IOW a
PID_x can be seen in a ctrl_mon group and a monitor group at the same
time. When a task is added to a ctrl_mon group, it is automatically
removed from the previous ctrl_mon group where it belonged. Similarly if
a task is moved to a monitor group it is removed from the previous
monitor group . Also since the monitor groups can only have subset of
tasks of parent ctrl_mon group, a task can be moved to a monitor group
only if its already present in the parent ctrl_mon group.

Task membership is indicated by a new field in the task_struct "u32
rmid" which holds the RMID for the task. RMID=0 is reserved for the
default root group where the tasks belong to at mount.

[tony: zero the rmid if rdtgroup was deleted when task was being moved]

Signed-off-by: Tony Luck <tony.luck@linux.intel.com>
Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Cc: reinette.chatre@intel.com
Link: http://lkml.kernel.org/r/1501017287-28083-16-git-send-email-vikas.shivappa@linux.intel.com
2017-08-01 22:41:24 +02:00
Vikas Shivappa 0734ded1ab x86/intel_rdt: Change closid type from int to u32
OS associates a CLOSid(Class of service id) to a task by writing the
high 32 bits of per CPU IA32_PQR_ASSOC MSR when a task is scheduled in.
CPUID.(EAX=10H, ECX=1):EDX[15:0] enumerates the max CLOSID supported and
it is zero indexed. Hence change the type to u32 from int.

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Cc: reinette.chatre@intel.com
Link: http://lkml.kernel.org/r/1501017287-28083-15-git-send-email-vikas.shivappa@linux.intel.com
2017-08-01 22:41:24 +02:00
Vikas Shivappa f01d7d51f5 x86/intel_rdt: Introduce a common compile option for RDT
We currently have a CONFIG_RDT_A which is for RDT(Resource directory
technology) allocation based resctrl filesystem interface. As a
preparation to add support for RDT monitoring as well into the same
resctrl filesystem, change the config option to be CONFIG_RDT which
would include both RDT allocation and monitoring code.

No functional change.

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Cc: reinette.chatre@intel.com
Link: http://lkml.kernel.org/r/1501017287-28083-4-git-send-email-vikas.shivappa@linux.intel.com
2017-08-01 22:41:19 +02:00
Linus Torvalds e06fdaf40a Now that IPC and other changes have landed, enable manual markings for
randstruct plugin, including the task_struct.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 Comment: Kees Cook <kees@outflux.net>
 
 iQIcBAABCgAGBQJZbRgGAAoJEIly9N/cbcAmk2AQAIL60aQ+9RIcFAXriFhnd7Z2
 x9Jqi9JNc8NgPFXx8GhE4J4eTZ5PwcjgXBpNRWY/laBkRyoBHn24ku09YxrJjmHz
 ZSUsP+/iO9lVeEfbmU9Tnk50afkfwx6bHXBwkiVGQWHtybNVUqA19JbqkHeg8ubx
 myKLGeUv5PPCodRIcBDD0+HaAANcsqtgbDpgmWU8s+IXWwvWCE2p7PuBw7v3HHgH
 qzlPDHYQCRDw+LWsSqPaHj+9mbRO18P/ydMoZHGH4Hl3YYNtty8ZbxnraI3A7zBL
 6mLUVcZ+/l88DqHc5I05T8MmLU1yl2VRxi8/jpMAkg9wkvZ5iNAtlEKIWU6eqsvk
 vaImNOkViLKlWKF+oUD1YdG16d8Segrc6m4MGdI021tb+LoGuUbkY7Tl4ee+3dl/
 9FM+jPv95HjJnyfRNGidh2TKTa9KJkh6DYM9aUnktMFy3ca1h/LuszOiN0LTDiHt
 k5xoFURk98XslJJyXM8FPwXCXiRivrXMZbg5ixNoS4aYSBLv7Cn1M6cPnSOs7UPh
 FqdNPXLRZ+vabSxvEg5+41Ioe0SHqACQIfaSsV5BfF2rrRRdaAxK4h7DBcI6owV2
 7ziBN1nBBq2onYGbARN6ApyCqLcchsKtQfiZ0iFsvW7ZawnkVOOObDTCgPl3tdkr
 403YXzphQVzJtpT5eRV6
 =ngAW
 -----END PGP SIGNATURE-----

Merge tag 'gcc-plugins-v4.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull structure randomization updates from Kees Cook:
 "Now that IPC and other changes have landed, enable manual markings for
  randstruct plugin, including the task_struct.

  This is the rest of what was staged in -next for the gcc-plugins, and
  comes in three patches, largest first:

   - mark "easy" structs with __randomize_layout

   - mark task_struct with an optional anonymous struct to isolate the
     __randomize_layout section

   - mark structs to opt _out_ of automated marking (which will come
     later)

  And, FWIW, this continues to pass allmodconfig (normal and patched to
  enable gcc-plugins) builds of x86_64, i386, arm64, arm, powerpc, and
  s390 for me"

* tag 'gcc-plugins-v4.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  randstruct: opt-out externally exposed function pointer structs
  task_struct: Allow randomized layout
  randstruct: Mark various structs for randomization
2017-07-19 08:55:18 -07:00
Akinobu Mita 9049f2f6e7 fault-inject: parse as natural 1-based value for fail-nth write interface
The value written to fail-nth file is parsed as 0-based.  Parsing as
one-based is more natural to understand and it enables to cancel the
previous setup by simply writing '0'.

This change also converts task->fail_nth from signed to unsigned int.

Link: http://lkml.kernel.org/r/1491490561-10485-3-git-send-email-akinobu.mita@gmail.com
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-14 15:05:13 -07:00
Dmitry Vyukov e41d58185f fault-inject: support systematic fault injection
Add /proc/self/task/<current-tid>/fail-nth file that allows failing
0-th, 1-st, 2-nd and so on calls systematically.
Excerpt from the added documentation:

 "Write to this file of integer N makes N-th call in the current task
  fail (N is 0-based). Read from this file returns a single char 'Y' or
  'N' that says if the fault setup with a previous write to this file
  was injected or not, and disables the fault if it wasn't yet injected.
  Note that this file enables all types of faults (slab, futex, etc).
  This setting takes precedence over all other generic settings like
  probability, interval, times, etc. But per-capability settings (e.g.
  fail_futex/ignore-private) take precedence over it. This feature is
  intended for systematic testing of faults in a single system call. See
  an example below"

Why add a new setting:
1. Existing settings are global rather than per-task.
   So parallel testing is not possible.
2. attr->interval is close but it depends on attr->count
   which is non reset to 0, so interval does not work as expected.
3. Trying to model this with existing settings requires manipulations
   of all of probability, interval, times, space, task-filter and
   unexposed count and per-task make-it-fail files.
4. Existing settings are per-failure-type, and the set of failure
   types is potentially expanding.
5. make-it-fail can't be changed by unprivileged user and aggressive
   stress testing better be done from an unprivileged user.
   Similarly, this would require opening the debugfs files to the
   unprivileged user, as he would need to reopen at least times file
   (not possible to pre-open before dropping privs).

The proposed interface solves all of the above (see the example).

We want to integrate this into syzkaller fuzzer.  A prototype has found
10 bugs in kernel in first day of usage:

  https://groups.google.com/forum/#!searchin/syzkaller/%22FAULT_INJECTION%22%7Csort:relevance

I've made the current interface work with all types of our sandboxes.
For setuid the secret sauce was prctl(PR_SET_DUMPABLE, 1, 0, 0, 0) to
make /proc entries non-root owned.  So I am fine with the current
version of the code.

[akpm@linux-foundation.org: fix build]
Link: http://lkml.kernel.org/r/20170328130128.101773-1-dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-12 16:26:01 -07:00
Linus Torvalds 4fde846ac0 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Thomas Gleixner:
 "This scheduler update provides:

   - The (hopefully) final fix for the vtime accounting issues which
     were around for quite some time

   - Use types known to user space in UAPI headers to unbreak user space
     builds

   - Make load balancing respect the current scheduling domain again
     instead of evaluating unrelated CPUs"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/headers/uapi: Fix linux/sched/types.h userspace compilation errors
  sched/fair: Fix load_balance() affinity redo path
  sched/cputime: Accumulate vtime on top of nsec clocksource
  sched/cputime: Move the vtime task fields to their own struct
  sched/cputime: Rename vtime fields
  sched/cputime: Always set tsk->vtime_snap_whence after accounting vtime
  vtime, sched/cputime: Remove vtime_account_user()
  Revert "sched/cputime: Refactor the cputime_adjust() code"
2017-07-09 10:52:16 -07:00
Vlastimil Babka 45816682b2 mm, mempolicy: stop adjusting current->il_next in mpol_rebind_nodemask()
The task->il_next variable stores the next allocation node id for task's
MPOL_INTERLEAVE policy.  mpol_rebind_nodemask() updates interleave and
bind mempolicies due to changing cpuset mems.  Currently it also tries
to make sure that current->il_next is valid within the updated nodemask.
This is bogus, because 1) we are updating potentially any task's
mempolicy, not just current, and 2) we might be updating a per-vma
mempolicy, not task one.

The interleave_nodes() function that uses il_next can cope fine with the
value not being within the currently allowed nodes, so this hasn't
manifested as an actual issue.

We can remove the need for updating il_next completely by changing it to
il_prev and store the node id of the previous interleave allocation
instead of the next id.  Then interleave_nodes() can calculate the next
id using the current nodemask and also store it as il_prev, except when
querying the next node via do_get_mempolicy().

Link: http://lkml.kernel.org/r/20170517081140.30654-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06 16:24:34 -07:00
Wanpeng Li 2a42eb9594 sched/cputime: Accumulate vtime on top of nsec clocksource
Currently the cputime source used by vtime is jiffies. When we cross
a context boundary and jiffies have changed since the last snapshot, the
pending cputime is accounted to the switching out context.

This system works ok if the ticks are not aligned across CPUs. If they
instead are aligned (ie: all fire at the same time) and the CPUs run in
userspace, the jiffies change is only observed on tick exit and therefore
the user cputime is accounted as system cputime. This is because the
CPU that maintains timekeeping fires its tick at the same time as the
others. It updates jiffies in the middle of the tick and the other CPUs
see that update on IRQ exit:

    CPU 0 (timekeeper)                  CPU 1
    -------------------              -------------
                      jiffies = N
    ...                              run in userspace for a jiffy
    tick entry                       tick entry (sees jiffies = N)
    set jiffies = N + 1
    tick exit                        tick exit (sees jiffies = N + 1)
                                                account 1 jiffy as stime

Fix this with using a nanosec clock source instead of jiffies. The
cputime is then accumulated and flushed everytime the pending delta
reaches a jiffy in order to mitigate the accounting overhead.

[ fweisbec: changelog, rebase on struct vtime, field renames, add delta
  on cputime readers, keep idle vtime as-is (low overhead accounting),
  harmonize clock sources. ]

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Luiz Capitulino <lcapitulino@redhat.com>
Tested-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1498756511-11714-6-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-05 09:54:15 +02:00
Frederic Weisbecker bac5b6b6b1 sched/cputime: Move the vtime task fields to their own struct
We are about to add vtime accumulation fields to the task struct. Let's
avoid more bloatification and gather vtime information to their own
struct.

Tested-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1498756511-11714-5-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-05 09:54:15 +02:00
Frederic Weisbecker 60a9ce57e7 sched/cputime: Rename vtime fields
The current "snapshot" based naming on vtime fields suggests we record
some past event but that's a low level picture of their actual purpose
which comes out blurry. The real point of these fields is to run a basic
state machine that tracks down cputime entry while switching between
contexts.

So lets reflect that with more meaningful names.

Tested-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1498756511-11714-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-05 09:54:14 +02:00
Linus Torvalds 9a9594efe5 Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull SMP hotplug updates from Thomas Gleixner:
 "This update is primarily a cleanup of the CPU hotplug locking code.

  The hotplug locking mechanism is an open coded RWSEM, which allows
  recursive locking. The main problem with that is the recursive nature
  as it evades the full lockdep coverage and hides potential deadlocks.

  The rework replaces the open coded RWSEM with a percpu RWSEM and
  establishes full lockdep coverage that way.

  The bulk of the changes fix up recursive locking issues and address
  the now fully reported potential deadlocks all over the place. Some of
  these deadlocks have been observed in the RT tree, but on mainline the
  probability was low enough to hide them away."

* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits)
  cpu/hotplug: Constify attribute_group structures
  powerpc: Only obtain cpu_hotplug_lock if called by rtasd
  ARM/hw_breakpoint: Fix possible recursive locking for arch_hw_breakpoint_init
  cpu/hotplug: Remove unused check_for_tasks() function
  perf/core: Don't release cred_guard_mutex if not taken
  cpuhotplug: Link lock stacks for hotplug callbacks
  acpi/processor: Prevent cpu hotplug deadlock
  sched: Provide is_percpu_thread() helper
  cpu/hotplug: Convert hotplug locking to percpu rwsem
  s390: Prevent hotplug rwsem recursion
  arm: Prevent hotplug rwsem recursion
  arm64: Prevent cpu hotplug rwsem recursion
  kprobes: Cure hotplug lock ordering issues
  jump_label: Reorder hotplug lock and jump_label_lock
  perf/tracing/cpuhotplug: Fix locking order
  ACPI/processor: Use cpu_hotplug_disable() instead of get_online_cpus()
  PCI: Replace the racy recursion prevention
  PCI: Use cpu_hotplug_disable() instead of get_online_cpus()
  perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode()
  x86/perf: Drop EXPORT of perf_check_microcode
  ...
2017-07-03 18:08:06 -07:00