When interrupts are shutdown, they are immediately deactivated in the
irqdomain hierarchy. While this looks obviously correct there is a subtle
issue:
There might be an interrupt in flight when free_irq() is invoking the
shutdown. This is properly handled at the irq descriptor / primary handler
level, but the deactivation might completely disable resources which are
required to acknowledge the interrupt.
Split the shutdown code and deactivate the interrupt after synchronization
in free_irq(). Fixup all other usage sites where this is not an issue to
invoke the combined shutdown_and_deactivate() function instead.
This still might be an issue if the interrupt in flight servicing is
delayed on a remote CPU beyond the invocation of synchronize_irq(), but
that cannot be handled at that level and needs to be handled in the
synchronize_irq() context.
Fixes: f8264e3496 ("irqdomain: Introduce new interfaces to support hierarchy irqdomains")
Reported-by: Robert Hodaszi <Robert.Hodaszi@digi.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/20190628111440.098196390@linutronix.de
!current->mm is not a reliable indicator for kernel threads as they might
temporarily use a user mm. Check for PF_KTHREAD instead.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1907021750100.1802@nanos.tec.linutronix.de
Christoph Hellwig says:
====================
Below is a series that cleans up the dev_pagemap interface so that it is
more easily usable, which removes the need to wrap it in hmm and thus
allowing to kill a lot of code
Changes since v3:
- pull in "mm/swap: Fix release_pages() when releasing devmap pages" and
rebase the other patches on top of that
- fold the hmm_devmem_add_resource into the DEVICE_PUBLIC memory removal
patch
- remove _vm_normal_page as it isn't needed without DEVICE_PUBLIC memory
- pick up various ACKs
Changes since v2:
- fix nvdimm kunit build
- add a new memory type for device dax
- fix a few issues in intermediate patches that didn't show up in the end
result
- incorporate feedback from Michal Hocko, including killing of
the DEVICE_PUBLIC memory type entirely
Changes since v1:
- rebase
- also switch p2pdma to the internal refcount
- add type checking for pgmap->type
- rename the migrate method to migrate_to_ram
- cleanup the altmap_valid flag
- various tidbits from the reviews
====================
Conflicts resolved by:
- Keeping Ira's version of the code in swap.c
- Using the delete for the section in hmm.rst
- Using the delete for the devmap code in hmm.c and .h
* branch 'hmm-devmem-cleanup.4': (24 commits)
mm: don't select MIGRATE_VMA_HELPER from HMM_MIRROR
mm: remove the HMM config option
mm: sort out the DEVICE_PRIVATE Kconfig mess
mm: simplify ZONE_DEVICE page private data
mm: remove hmm_devmem_add
mm: remove hmm_vma_alloc_locked_page
nouveau: use devm_memremap_pages directly
nouveau: use alloc_page_vma directly
PCI/P2PDMA: use the dev_pagemap internal refcount
device-dax: use the dev_pagemap internal refcount
memremap: provide an optional internal refcount in struct dev_pagemap
memremap: replace the altmap_valid field with a PGMAP_ALTMAP_VALID flag
memremap: remove the data field in struct dev_pagemap
memremap: add a migrate_to_ram method to struct dev_pagemap_ops
memremap: lift the devmap_enable manipulation into devm_memremap_pages
memremap: pass a struct dev_pagemap to ->kill and ->cleanup
memremap: move dev_pagemap callbacks into a separate structure
memremap: validate the pagemap type passed to devm_memremap_pages
mm: factor out a devm_request_free_mem_region helper
mm: export alloc_pages_vma
...
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
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Merge tag 'v5.2-rc7' into rdma.git hmm
Required for dependencies in the next patches.
Provide an internal refcounting logic if no ->ref field is provided
in the pagemap passed into devm_memremap_pages so that callers don't
have to reinvent it poorly.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Add a flags field to struct dev_pagemap to replace the altmap_valid
boolean to be a little more extensible. Also add a pgmap_altmap() helper
to find the optional altmap and clean up the code using the altmap using
it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
struct dev_pagemap is always embedded into a containing structure, so
there is no need to an additional private data field.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This replaces the hacky ->fault callback, which is currently directly
called from common code through a hmm specific data structure as an
exercise in layering violations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Just check if there is a ->page_free operation set and take care of the
static key enable, as well as the put using device managed resources.
Also check that a ->page_free is provided for the pgmaps types that
require it, and check for a valid type as well while we are at it.
Note that this also fixes the fact that hmm never called
dev_pagemap_put_ops and thus would leave the slow path enabled forever,
even after a device driver unload or disable.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Passing the actual typed structure leads to more understandable code
vs just passing the ref member.
Reported-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
The dev_pagemap is a growing too many callbacks. Move them into a
separate ops structure so that they are not duplicated for multiple
instances, and an attacker can't easily overwrite them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Most pgmap types are only supported when certain config options are
enabled. Check for a type that is valid for the current configuration
before setting up the pagemap. For this the usage of the 0 type for
device dax gets replaced with an explicit MEMORY_DEVICE_DEVDAX type.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Keep the physical address allocation that hmm_add_device does with the
rest of the resource code, and allow future reuse of it without the hmm
wrapper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
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Merge tag 'v5.2-rc6' into for-5.3/block
Merge 5.2-rc6 into for-5.3/block, so we get the same page merge leak
fix. Otherwise we end up having conflicts with future patches between
for-5.3/block and master that touch this area. In particular, it makes
the bio_full() fix hard to backport to stable.
* tag 'v5.2-rc6': (482 commits)
Linux 5.2-rc6
Revert "iommu/vt-d: Fix lock inversion between iommu->lock and device_domain_lock"
Bluetooth: Fix regression with minimum encryption key size alignment
tcp: refine memory limit test in tcp_fragment()
x86/vdso: Prevent segfaults due to hoisted vclock reads
SUNRPC: Fix a credential refcount leak
Revert "SUNRPC: Declare RPC timers as TIMER_DEFERRABLE"
net :sunrpc :clnt :Fix xps refcount imbalance on the error path
NFS4: Only set creation opendata if O_CREAT
ARM: 8867/1: vdso: pass --be8 to linker if necessary
KVM: nVMX: reorganize initial steps of vmx_set_nested_state
KVM: PPC: Book3S HV: Invalidate ERAT when flushing guest TLB entries
habanalabs: use u64_to_user_ptr() for reading user pointers
nfsd: replace Jeff by Chuck as nfsd co-maintainer
inet: clear num_timeout reqsk_alloc()
PCI/P2PDMA: Ignore root complex whitelist when an IOMMU is present
net: mvpp2: debugfs: Add pmap to fs dump
ipv6: Default fib6_type to RTN_UNICAST when not set
net: hns3: Fix inconsistent indenting
net/af_iucv: always register net_device notifier
...
During soft reboot(kexec_file_load) boot command line
arguments are not measured.
Call ima hook ima_kexec_cmdline to measure the boot command line
arguments into IMA measurement list.
- call ima_kexec_cmdline from kexec_file_load.
- move the call ima_add_kexec_buffer after the cmdline
args have been measured.
Signed-off-by: Prakhar Srivastava <prsriva02@gmail.com>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Pull SMP fixes from Thomas Gleixner:
"Two small changes for the cpu hotplug code:
- Prevent out of bounds access which actually might crash the machine
caused by a missing bounds check in the fail injection code
- Warn about unsupported migitation mode command line arguments to
make people aware that they typoed the paramater. Not necessarily a
fix but quite some people tripped over that"
* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpu/hotplug: Fix out-of-bounds read when setting fail state
cpu/speculation: Warn on unsupported mitigations= parameter
Pull perf fixes from Ingo Molnar:
"Various fixes, most of them related to bugs perf fuzzing found in the
x86 code"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/regs: Use PERF_REG_EXTENDED_MASK
perf/x86: Remove pmu->pebs_no_xmm_regs
perf/x86: Clean up PEBS_XMM_REGS
perf/x86/regs: Check reserved bits
perf/x86: Disable extended registers for non-supported PMUs
perf/ioctl: Add check for the sample_period value
perf/core: Fix perf_sample_regs_user() mm check
Avoid skipping bus-level PCI power management during system
resume for PCIe ports left in D0 during the preceding suspend
transition on platforms where the power states of those ports
can change out of the PCI layer's control.
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Merge tag 'pm-5.2-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fix from Rafael Wysocki:
"Avoid skipping bus-level PCI power management during system resume for
PCIe ports left in D0 during the preceding suspend transition on
platforms where the power states of those ports can change out of the
PCI layer's control"
* tag 'pm-5.2-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PCI: PM: Avoid skipping bus-level PM on platforms without ACPI
Commit 5eed6f1dff ("fork,memcg: fix crash in free_thread_stack on
memcg charge fail") corrected two instances, but there was a third
instance of this bug.
Without setting tsk->stack, if memcg_charge_kernel_stack fails, it'll
execute free_thread_stack() on a dangling pointer.
Enterprise kernels are compiled with VMAP_STACK=y so this isn't
critical, but custom VMAP_STACK=n builds should have some performance
advantage, with the drawback of risking to fail fork because compaction
didn't succeed. So as long as VMAP_STACK=n is a supported option it's
worth fixing it upstream.
Link: http://lkml.kernel.org/r/20190619011450.28048-1-aarcange@redhat.com
Fixes: 9b6f7e163c ("mm: rework memcg kernel stack accounting")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the minimal fix for stable, I'll send cleanups later.
Commit 854a6ed568 ("signal: Add restore_user_sigmask()") introduced
the visible change which breaks user-space: a signal temporary unblocked
by set_user_sigmask() can be delivered even if the caller returns
success or timeout.
Change restore_user_sigmask() to accept the additional "interrupted"
argument which should be used instead of signal_pending() check, and
update the callers.
Eric said:
: For clarity. I don't think this is required by posix, or fundamentally to
: remove the races in select. It is what linux has always done and we have
: applications who care so I agree this fix is needed.
:
: Further in any case where the semantic change that this patch rolls back
: (aka where allowing a signal to be delivered and the select like call to
: complete) would be advantage we can do as well if not better by using
: signalfd.
:
: Michael is there any chance we can get this guarantee of the linux
: implementation of pselect and friends clearly documented. The guarantee
: that if the system call completes successfully we are guaranteed that no
: signal that is unblocked by using sigmask will be delivered?
Link: http://lkml.kernel.org/r/20190604134117.GA29963@redhat.com
Fixes: 854a6ed568 ("signal: Add restore_user_sigmask()")
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Eric Wong <e@80x24.org>
Tested-by: Eric Wong <e@80x24.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: <stable@vger.kernel.org> [5.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We don't currently allow lookups into a devmap from eBPF, because the map
lookup returns a pointer directly to the dev->ifindex, which shouldn't be
modifiable from eBPF.
However, being able to do lookups in devmaps is useful to know (e.g.)
whether forwarding to a specific interface is enabled. Currently, programs
work around this by keeping a shadow map of another type which indicates
whether a map index is valid.
Since we now have a flag to make maps read-only from the eBPF side, we can
simply lift the lookup restriction if we make sure this flag is always set.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The socket map uses a linked list instead of a bitmap to keep track of
which entries to flush. Do the same for devmap and cpumap, as this means we
don't have to care about the map index when enqueueing things into the
map (and so we can cache the map lookup).
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add a helper in list.h for the non-standard way of clearing a list that is
used in xskmap. This makes it easier to reuse it in the other map types,
and also makes sure this usage is not forgotten in any list refactorings in
the future.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The commit 9f255b632b ("module: Fix livepatch/ftrace module text
permissions race") causes a possible deadlock between register_kprobe()
and ftrace_run_update_code() when ftrace is using stop_machine().
The existing dependency chain (in reverse order) is:
-> #1 (text_mutex){+.+.}:
validate_chain.isra.21+0xb32/0xd70
__lock_acquire+0x4b8/0x928
lock_acquire+0x102/0x230
__mutex_lock+0x88/0x908
mutex_lock_nested+0x32/0x40
register_kprobe+0x254/0x658
init_kprobes+0x11a/0x168
do_one_initcall+0x70/0x318
kernel_init_freeable+0x456/0x508
kernel_init+0x22/0x150
ret_from_fork+0x30/0x34
kernel_thread_starter+0x0/0xc
-> #0 (cpu_hotplug_lock.rw_sem){++++}:
check_prev_add+0x90c/0xde0
validate_chain.isra.21+0xb32/0xd70
__lock_acquire+0x4b8/0x928
lock_acquire+0x102/0x230
cpus_read_lock+0x62/0xd0
stop_machine+0x2e/0x60
arch_ftrace_update_code+0x2e/0x40
ftrace_run_update_code+0x40/0xa0
ftrace_startup+0xb2/0x168
register_ftrace_function+0x64/0x88
klp_patch_object+0x1a2/0x290
klp_enable_patch+0x554/0x980
do_one_initcall+0x70/0x318
do_init_module+0x6e/0x250
load_module+0x1782/0x1990
__s390x_sys_finit_module+0xaa/0xf0
system_call+0xd8/0x2d0
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(text_mutex);
lock(cpu_hotplug_lock.rw_sem);
lock(text_mutex);
lock(cpu_hotplug_lock.rw_sem);
It is similar problem that has been solved by the commit 2d1e38f566
("kprobes: Cure hotplug lock ordering issues"). Many locks are involved.
To be on the safe side, text_mutex must become a low level lock taken
after cpu_hotplug_lock.rw_sem.
This can't be achieved easily with the current ftrace design.
For example, arm calls set_all_modules_text_rw() already in
ftrace_arch_code_modify_prepare(), see arch/arm/kernel/ftrace.c.
This functions is called:
+ outside stop_machine() from ftrace_run_update_code()
+ without stop_machine() from ftrace_module_enable()
Fortunately, the problematic fix is needed only on x86_64. It is
the only architecture that calls set_all_modules_text_rw()
in ftrace path and supports livepatching at the same time.
Therefore it is enough to move text_mutex handling from the generic
kernel/trace/ftrace.c into arch/x86/kernel/ftrace.c:
ftrace_arch_code_modify_prepare()
ftrace_arch_code_modify_post_process()
This patch basically reverts the ftrace part of the problematic
commit 9f255b632b ("module: Fix livepatch/ftrace module
text permissions race"). And provides x86_64 specific-fix.
Some refactoring of the ftrace code will be needed when livepatching
is implemented for arm or nds32. These architectures call
set_all_modules_text_rw() and use stop_machine() at the same time.
Link: http://lkml.kernel.org/r/20190627081334.12793-1-pmladek@suse.com
Fixes: 9f255b632b ("module: Fix livepatch/ftrace module text permissions race")
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
[
As reviewed by Miroslav Benes <mbenes@suse.cz>, removed return value of
ftrace_run_update_code() as it is a void function.
]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This adds the pidfd_open() syscall. It allows a caller to retrieve pollable
pidfds for a process which did not get created via CLONE_PIDFD, i.e. for a
process that is created via traditional fork()/clone() calls that is only
referenced by a PID:
int pidfd = pidfd_open(1234, 0);
ret = pidfd_send_signal(pidfd, SIGSTOP, NULL, 0);
With the introduction of pidfds through CLONE_PIDFD it is possible to
created pidfds at process creation time.
However, a lot of processes get created with traditional PID-based calls
such as fork() or clone() (without CLONE_PIDFD). For these processes a
caller can currently not create a pollable pidfd. This is a problem for
Android's low memory killer (LMK) and service managers such as systemd.
Both are examples of tools that want to make use of pidfds to get reliable
notification of process exit for non-parents (pidfd polling) and race-free
signal sending (pidfd_send_signal()). They intend to switch to this API for
process supervision/management as soon as possible. Having no way to get
pollable pidfds from PID-only processes is one of the biggest blockers for
them in adopting this api. With pidfd_open() making it possible to retrieve
pidfds for PID-based processes we enable them to adopt this api.
In line with Arnd's recent changes to consolidate syscall numbers across
architectures, I have added the pidfd_open() syscall to all architectures
at the same time.
Signed-off-by: Christian Brauner <christian@brauner.io>
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jann Horn <jannh@google.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-api@vger.kernel.org
This patch adds polling support to pidfd.
Android low memory killer (LMK) needs to know when a process dies once
it is sent the kill signal. It does so by checking for the existence of
/proc/pid which is both racy and slow. For example, if a PID is reused
between when LMK sends a kill signal and checks for existence of the
PID, since the wrong PID is now possibly checked for existence.
Using the polling support, LMK will be able to get notified when a process
exists in race-free and fast way, and allows the LMK to do other things
(such as by polling on other fds) while awaiting the process being killed
to die.
For notification to polling processes, we follow the same existing
mechanism in the kernel used when the parent of the task group is to be
notified of a child's death (do_notify_parent). This is precisely when the
tasks waiting on a poll of pidfd are also awakened in this patch.
We have decided to include the waitqueue in struct pid for the following
reasons:
1. The wait queue has to survive for the lifetime of the poll. Including
it in task_struct would not be option in this case because the task can
be reaped and destroyed before the poll returns.
2. By including the struct pid for the waitqueue means that during
de_thread(), the new thread group leader automatically gets the new
waitqueue/pid even though its task_struct is different.
Appropriate test cases are added in the second patch to provide coverage of
all the cases the patch is handling.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Daniel Colascione <dancol@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Tim Murray <timmurray@google.com>
Cc: Jonathan Kowalski <bl0pbl33p@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: kernel-team@android.com
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Co-developed-by: Daniel Colascione <dancol@google.com>
Signed-off-by: Daniel Colascione <dancol@google.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Christian Brauner <christian@brauner.io>
Use zeroing allocator instead of using allocator
followed with memset with 0
Signed-off-by: Fuqian Huang <huangfq.daxian@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The new route handling in ip_mc_finish_output() from 'net' overlapped
with the new support for returning congestion notifications from BPF
programs.
In order to handle this I had to take the dev_loopback_xmit() calls
out of the switch statement.
The aquantia driver conflicts were simple overlapping changes.
Signed-off-by: David S. Miller <davem@davemloft.net>
Implement new BPF_PROG_TYPE_CGROUP_SOCKOPT program type and
BPF_CGROUP_{G,S}ETSOCKOPT cgroup hooks.
BPF_CGROUP_SETSOCKOPT can modify user setsockopt arguments before
passing them down to the kernel or bypass kernel completely.
BPF_CGROUP_GETSOCKOPT can can inspect/modify getsockopt arguments that
kernel returns.
Both hooks reuse existing PTR_TO_PACKET{,_END} infrastructure.
The buffer memory is pre-allocated (because I don't think there is
a precedent for working with __user memory from bpf). This might be
slow to do for each {s,g}etsockopt call, that's why I've added
__cgroup_bpf_prog_array_is_empty that exits early if there is nothing
attached to a cgroup. Note, however, that there is a race between
__cgroup_bpf_prog_array_is_empty and BPF_PROG_RUN_ARRAY where cgroup
program layout might have changed; this should not be a problem
because in general there is a race between multiple calls to
{s,g}etsocktop and user adding/removing bpf progs from a cgroup.
The return code of the BPF program is handled as follows:
* 0: EPERM
* 1: success, continue with next BPF program in the cgroup chain
v9:
* allow overwriting setsockopt arguments (Alexei Starovoitov):
* use set_fs (same as kernel_setsockopt)
* buffer is always kzalloc'd (no small on-stack buffer)
v8:
* use s32 for optlen (Andrii Nakryiko)
v7:
* return only 0 or 1 (Alexei Starovoitov)
* always run all progs (Alexei Starovoitov)
* use optval=0 as kernel bypass in setsockopt (Alexei Starovoitov)
(decided to use optval=-1 instead, optval=0 might be a valid input)
* call getsockopt hook after kernel handlers (Alexei Starovoitov)
v6:
* rework cgroup chaining; stop as soon as bpf program returns
0 or 2; see patch with the documentation for the details
* drop Andrii's and Martin's Acked-by (not sure they are comfortable
with the new state of things)
v5:
* skip copy_to_user() and put_user() when ret == 0 (Martin Lau)
v4:
* don't export bpf_sk_fullsock helper (Martin Lau)
* size != sizeof(__u64) for uapi pointers (Martin Lau)
* offsetof instead of bpf_ctx_range when checking ctx access (Martin Lau)
v3:
* typos in BPF_PROG_CGROUP_SOCKOPT_RUN_ARRAY comments (Andrii Nakryiko)
* reverse christmas tree in BPF_PROG_CGROUP_SOCKOPT_RUN_ARRAY (Andrii
Nakryiko)
* use __bpf_md_ptr instead of __u32 for optval{,_end} (Martin Lau)
* use BPF_FIELD_SIZEOF() for consistency (Martin Lau)
* new CG_SOCKOPT_ACCESS macro to wrap repeated parts
v2:
* moved bpf_sockopt_kern fields around to remove a hole (Martin Lau)
* aligned bpf_sockopt_kern->buf to 8 bytes (Martin Lau)
* bpf_prog_array_is_empty instead of bpf_prog_array_length (Martin Lau)
* added [0,2] return code check to verifier (Martin Lau)
* dropped unused buf[64] from the stack (Martin Lau)
* use PTR_TO_SOCKET for bpf_sockopt->sk (Martin Lau)
* dropped bpf_target_off from ctx rewrites (Martin Lau)
* use return code for kernel bypass (Martin Lau & Andrii Nakryiko)
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
That gets rid of this warning:
./kernel/time/hrtimer.c:1119: WARNING: Block quote ends without a blank line; unexpected unindent.
and displays nicely both at the source code and at the produced
documentation.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linux Doc Mailing List <linux-doc@vger.kernel.org>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Link: https://lkml.kernel.org/r/74ddad7dac331b4e5ce4a90e15c8a49e3a16d2ac.1561372382.git.mchehab+samsung@kernel.org
All callers use GFP_KERNEL. No point in having that argument.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
None of those functions have any users outside of workqueue.c. Confine
them.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since commit 4bfc0bb2c6 ("bpf: decouple the lifetime of cgroup_bpf
from cgroup itself"), cgroup_bpf release occurs asynchronously
(from a worker context), and before the release of the cgroup itself.
This introduced a previously non-existing race between the release
and update paths. E.g. if a leaf's cgroup_bpf is released and a new
bpf program is attached to the one of ancestor cgroups at the same
time. The race may result in double-free and other memory corruptions.
To fix the problem, let's protect the body of cgroup_bpf_release()
with cgroup_mutex, as it was effectively previously, when all this
code was called from the cgroup release path with cgroup mutex held.
Also let's skip cgroups, which have no chances to invoke a bpf
program, on the update path. If the cgroup bpf refcnt reached 0,
it means that the cgroup is offline (no attached processes), and
there are no associated sockets left. It means there is no point
in updating effective progs array! And it can lead to a leak,
if it happens after the release. So, let's skip such cgroups.
Big thanks for Tejun Heo for discovering and debugging of this problem!
Fixes: 4bfc0bb2c6 ("bpf: decouple the lifetime of cgroup_bpf from cgroup itself")
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
anon_inode_getfd() should be used *ONLY* in situations when we are
guaranteed to be past the last failure point (including copying the
descriptor number to userland, at that). And ksys_close() should
not be used for cleanups at all.
anon_inode_getfile() is there for all nontrivial cases like that.
Just use that...
Fixes: b3e5838252 ("clone: add CLONE_PIDFD")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Jann Horn <jannh@google.com>
Signed-off-by: Christian Brauner <christian@brauner.io>
Setting invalid value to /sys/devices/system/cpu/cpuX/hotplug/fail
can control `struct cpuhp_step *sp` address, results in the following
global-out-of-bounds read.
Reproducer:
# echo -2 > /sys/devices/system/cpu/cpu0/hotplug/fail
KASAN report:
BUG: KASAN: global-out-of-bounds in write_cpuhp_fail+0x2cd/0x2e0
Read of size 8 at addr ffffffff89734438 by task bash/1941
CPU: 0 PID: 1941 Comm: bash Not tainted 5.2.0-rc6+ #31
Call Trace:
write_cpuhp_fail+0x2cd/0x2e0
dev_attr_store+0x58/0x80
sysfs_kf_write+0x13d/0x1a0
kernfs_fop_write+0x2bc/0x460
vfs_write+0x1e1/0x560
ksys_write+0x126/0x250
do_syscall_64+0xc1/0x390
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f05e4f4c970
The buggy address belongs to the variable:
cpu_hotplug_lock+0x98/0xa0
Memory state around the buggy address:
ffffffff89734300: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
ffffffff89734380: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff89734400: 00 00 00 00 fa fa fa fa 00 00 00 00 fa fa fa fa
^
ffffffff89734480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffffff89734500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Add a sanity check for the value written from user space.
Fixes: 1db49484f2 ("smp/hotplug: Hotplug state fail injection")
Signed-off-by: Eiichi Tsukata <devel@etsukata.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: peterz@infradead.org
Link: https://lkml.kernel.org/r/20190627024732.31672-1-devel@etsukata.com
... since we immediately follow that with check that it *is* an
opened perf file, with O_PATH ones ending with with the same
-EBADF we'd get for descriptor that isn't opened at all.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There are platforms that do not call pm_set_suspend_via_firmware(),
so pm_suspend_via_firmware() returns 'false' on them, but the power
states of PCI devices (PCIe ports in particular) are changed as a
result of powering down core platform components during system-wide
suspend. Thus the pm_suspend_via_firmware() checks in
pci_pm_suspend_noirq() and pci_pm_resume_noirq() introduced by
commit 3e26c5feed ("PCI: PM: Skip devices in D0 for suspend-to-
idle") are not sufficient to determine that devices left in D0
during suspend will remain in D0 during resume and so the bus-level
power management can be skipped for them.
For this reason, introduce a new global suspend flag,
PM_SUSPEND_FLAG_NO_PLATFORM, set it for suspend-to-idle only
and replace the pm_suspend_via_firmware() checks mentioned above
with checks against this flag.
Fixes: 3e26c5feed ("PCI: PM: Skip devices in D0 for suspend-to-idle")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Move the user and user-session keyrings to the user_namespace struct rather
than pinning them from the user_struct struct. This prevents these
keyrings from propagating across user-namespaces boundaries with regard to
the KEY_SPEC_* flags, thereby making them more useful in a containerised
environment.
The issue is that a single user_struct may be represent UIDs in several
different namespaces.
The way the patch does this is by attaching a 'register keyring' in each
user_namespace and then sticking the user and user-session keyrings into
that. It can then be searched to retrieve them.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jann Horn <jannh@google.com>
Keyring names are held in a single global list that any process can pick
from by means of keyctl_join_session_keyring (provided the keyring grants
Search permission). This isn't very container friendly, however.
Make the following changes:
(1) Make default session, process and thread keyring names begin with a
'.' instead of '_'.
(2) Keyrings whose names begin with a '.' aren't added to the list. Such
keyrings are system specials.
(3) Replace the global list with per-user_namespace lists. A keyring adds
its name to the list for the user_namespace that it is currently in.
(4) When a user_namespace is deleted, it just removes itself from the
keyring name list.
The global keyring_name_lock is retained for accessing the name lists.
This allows (4) to work.
This can be tested by:
# keyctl newring foo @s
995906392
# unshare -U
$ keyctl show
...
995906392 --alswrv 65534 65534 \_ keyring: foo
...
$ keyctl session foo
Joined session keyring: 935622349
As can be seen, a new session keyring was created.
The capability bit KEYCTL_CAPS1_NS_KEYRING_NAME is set if the kernel is
employing this feature.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Eric W. Biederman <ebiederm@xmission.com>
If CONFIG_ARCH_HAS_STRICT_MODULE_RWX is not defined,
we need stub for module_enable_nx() and module_enable_x().
If CONFIG_ARCH_HAS_STRICT_MODULE_RWX is defined, but
CONFIG_STRICT_MODULE_RWX is disabled, we need stub for
module_enable_nx.
Move frob_text() outside of the CONFIG_STRICT_MODULE_RWX,
because it is needed anyway.
Fixes: 2eef1399a8 ("modules: fix BUG when load module with rodata=n")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Currently, if the user specifies an unsupported mitigation strategy on the
kernel command line, it will be ignored silently. The code will fall back
to the default strategy, possibly leaving the system more vulnerable than
expected.
This may happen due to e.g. a simple typo, or, for a stable kernel release,
because not all mitigation strategies have been backported.
Inform the user by printing a message.
Fixes: 98af845294 ("cpu/speculation: Add 'mitigations=' cmdline option")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190516070935.22546-1-geert@linux-m68k.org
Yauheni reported the following code do not work correctly on BE arches:
ALU_ARSH_X:
DST = (u64) (u32) ((*(s32 *) &DST) >> SRC);
CONT;
ALU_ARSH_K:
DST = (u64) (u32) ((*(s32 *) &DST) >> IMM);
CONT;
and are causing failure of test_verifier test 'arsh32 on imm 2' on BE
arches.
The code is taking address and interpreting memory directly, so is not
endianness neutral. We should instead perform standard C type casting on
the variable. A u64 to s32 conversion will drop the high 32-bit and reserve
the low 32-bit as signed integer, this is all we want.
Fixes: 2dc6b100f9 ("bpf: interpreter support BPF_ALU | BPF_ARSH")
Reported-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
With CONFIG_MODULES=n, the following compiler warning occurs:
/data/users/yhs/work/net-next/kernel/trace/bpf_trace.c:605:13: warning:
‘do_bpf_send_signal’ defined but not used [-Wunused-function]
static void do_bpf_send_signal(struct irq_work *entry)
The __init function send_signal_irq_work_init(), which calls
do_bpf_send_signal(), is defined under CONFIG_MODULES. Hence,
when CONFIG_MODULES=n, nobody calls static function do_bpf_send_signal(),
hence the warning.
The init function send_signal_irq_work_init() should work without
CONFIG_MODULES. Moving it out of CONFIG_MODULES
code section fixed the compiler warning, and also make bpf_send_signal()
helper work without CONFIG_MODULES.
Fixes: 8b401f9ed2 ("bpf: implement bpf_send_signal() helper")
Reported-By: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
DMA_ATTR_NO_KERNEL_MAPPING is generally implemented by allocating
normal cacheable pages or CMA memory, and then returning the page
pointer as the opaque handle. Lift that code from the xtensa and
generic dma remapping implementations into the generic dma-direct
code so that we don't even call arch_dma_alloc for these allocations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Only call into arch_dma_alloc if we require an uncached mapping,
and remove the parisc code manually doing normal cached
DMA_ATTR_NON_CONSISTENT allocations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Helge Deller <deller@gmx.de> # parisc
This is introduced for admins to check what is happening on XDP_TX when
bulk XDP_TX is in use, which will be first introduced in veth in next
commit.
v3:
- Add act field to be in line with other XDP tracepoints.
Signed-off-by: Toshiaki Makita <toshiaki.makita1@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
When system has been running for a long time, signed integer
counters are not enough for some lockdep statistics. Using
unsigned long counters can satisfy the requirement. Besides,
most of lockdep statistics are unsigned. It is better to use
unsigned int instead of int.
Remove unused variables.
- max_recursion_depth
- nr_cyclic_check_recursions
- nr_find_usage_forwards_recursions
- nr_find_usage_backwards_recursions
Signed-off-by: Kobe Wu <kobe-cp.wu@mediatek.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <linux-mediatek@lists.infradead.org>
Cc: <wsd_upstream@mediatek.com>
Cc: Eason Lin <eason-yh.lin@mediatek.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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/1561365348-16050-1-git-send-email-kobe-cp.wu@mediatek.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The last cleanup patch triggered another issue, as now another function
should be moved into the same section:
kernel/locking/lockdep.c:3580:12: error: 'mark_lock' defined but not used [-Werror=unused-function]
static int mark_lock(struct task_struct *curr, struct held_lock *this,
Move mark_lock() into the same #ifdef section as its only caller, and
remove the now-unused mark_lock_irq() stub helper.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yuyang Du <duyuyang@gmail.com>
Fixes: 0d2cc3b345 ("locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING")
Link: https://lkml.kernel.org/r/20190617124718.1232976-1-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Check if we need to allocate uncached memory for a device given the
allocation flags. Switch over the uncached segment check to this helper
to deal with architectures that do not support the dma_cache_sync
operation and thus should not returned cacheable memory for
DMA_ATTR_NON_CONSISTENT allocations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
The dma masks in struct device are always 64-bits wide. But for builds
using a 32-bit dma_addr_t we need to ensure we don't store an
unsupportable value. Before Linux 5.0 this was handled at least by
the ARM dma mapping code by never allowing to set a larger dma_mask,
but these days we allow the driver to just set the largest supported
value and never fall back to a smaller one. Ensure this always works
by truncating the value.
Fixes: 9eb9e96e97 ("Documentation/DMA-API-HOWTO: update dma_mask sections")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Currently perf_rotate_context assumes that if the context's nr_events !=
nr_active a rotation is necessary for perf event multiplexing. With
cgroups, nr_events is the total count of events for all cgroups and
nr_active will not include events in a cgroup other than the current
task's. This makes rotation appear necessary for cgroups when it is not.
Add a perf_event_context flag that is set when rotation is necessary.
Clear the flag during sched_out and set it when a flexible sched_in
fails due to resources.
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: https://lkml.kernel.org/r/20190601082722.44543-1-irogers@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The Energy Aware Scheduler (EAS) estimates the energy impact of waking
up a task on a given CPU. This estimation is based on:
a) an (active) power consumption defined for each CPU frequency
b) an estimation of which frequency will be used on each CPU
c) an estimation of the busy time (utilization) of each CPU
Utilization clamping can affect both b) and c).
A CPU is expected to run:
- on an higher than required frequency, but for a shorter time, in case
its estimated utilization will be smaller than the minimum utilization
enforced by uclamp
- on a smaller than required frequency, but for a longer time, in case
its estimated utilization is bigger than the maximum utilization
enforced by uclamp
While compute_energy() already accounts clamping effects on busy time,
the clamping effects on frequency selection are currently ignored.
Fix it by considering how CPU clamp values will be affected by a
task waking up and being RUNNABLE on that CPU.
Do that by refactoring schedutil_freq_util() to take an additional
task_struct* which allows EAS to evaluate the impact on clamp values of
a task being eventually queued in a CPU. Clamp values are applied to the
RT+CFS utilization only when a FREQUENCY_UTIL is required by
compute_energy().
Do note that switching from ENERGY_UTIL to FREQUENCY_UTIL in the
computation of the cpu_util signal implies that we are more likely to
estimate the highest OPP when a RT task is running in another CPU of
the same performance domain. This can have an impact on energy
estimation but:
- it's not easy to say which approach is better, since it depends on
the use case
- the original approach could still be obtained by setting a smaller
task-specific util_min whenever required
Since we are at that:
- rename schedutil_freq_util() into schedutil_cpu_util(),
since it's not only used for frequency selection.
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/20190621084217.8167-12-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So far uclamp_util() allows to clamp a specified utilization considering
the clamp values requested by RUNNABLE tasks in a CPU. For the Energy
Aware Scheduler (EAS) it is interesting to test how clamp values will
change when a task is becoming RUNNABLE on a given CPU.
For example, EAS is interested in comparing the energy impact of
different scheduling decisions and the clamp values can play a role on
that.
Add uclamp_util_with() which allows to clamp a given utilization by
considering the possible impact on CPU clamp values of a specified task.
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/20190621084217.8167-11-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Each time a frequency update is required via schedutil, a frequency is
selected to (possibly) satisfy the utilization reported by each
scheduling class and irqs. However, when utilization clamping is in use,
the frequency selection should consider userspace utilization clamping
hints. This will allow, for example, to:
- boost tasks which are directly affecting the user experience
by running them at least at a minimum "requested" frequency
- cap low priority tasks not directly affecting the user experience
by running them only up to a maximum "allowed" frequency
These constraints are meant to support a per-task based tuning of the
frequency selection thus supporting a fine grained definition of
performance boosting vs energy saving strategies in kernel space.
Add support to clamp the utilization of RUNNABLE FAIR and RT tasks
within the boundaries defined by their aggregated utilization clamp
constraints.
Do that by considering the max(min_util, max_util) to give boosted tasks
the performance they need even when they happen to be co-scheduled with
other capped tasks.
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/20190621084217.8167-10-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
By default FAIR tasks start without clamps, i.e. neither boosted nor
capped, and they run at the best frequency matching their utilization
demand. This default behavior does not fit RT tasks which instead are
expected to run at the maximum available frequency, if not otherwise
required by explicitly capping them.
Enforce the correct behavior for RT tasks by setting util_min to max
whenever:
1. the task is switched to the RT class and it does not already have a
user-defined clamp value assigned.
2. an RT task is forked from a parent with RESET_ON_FORK set.
NOTE: utilization clamp values are cross scheduling class attributes and
thus they are never changed/reset once a value has been explicitly
defined from user-space.
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/20190621084217.8167-9-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A forked tasks gets the same clamp values of its parent however, when
the RESET_ON_FORK flag is set on parent, e.g. via:
sys_sched_setattr()
sched_setattr()
__sched_setscheduler(attr::SCHED_FLAG_RESET_ON_FORK)
the new forked task is expected to start with all attributes reset to
default values.
Do that for utilization clamp values too by checking the reset request
from the existing uclamp_fork() call which already provides the required
initialization for other uclamp related bits.
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/20190621084217.8167-8-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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>
The sched_setattr() syscall mandates that a policy is always specified.
This requires to always know which policy a task will have when
attributes are configured and this makes it impossible to add more
generic task attributes valid across different scheduling policies.
Reading the policy before setting generic tasks attributes is racy since
we cannot be sure it is not changed concurrently.
Introduce the required support to change generic task attributes without
affecting the current task policy. This is done by adding an attribute flag
(SCHED_FLAG_KEEP_POLICY) to enforce the usage of the current policy.
Add support for the SETPARAM_POLICY policy, which is already used by the
sched_setparam() POSIX syscall, to the sched_setattr() non-POSIX
syscall.
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/20190621084217.8167-6-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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>
When a task sleeps it removes its max utilization clamp from its CPU.
However, the blocked utilization on that CPU can be higher than the max
clamp value enforced while the task was running. This allows undesired
CPU frequency increases while a CPU is idle, for example, when another
CPU on the same frequency domain triggers a frequency update, since
schedutil can now see the full not clamped blocked utilization of the
idle CPU.
Fix this by using:
uclamp_rq_dec_id(p, rq, UCLAMP_MAX)
uclamp_rq_max_value(rq, UCLAMP_MAX, clamp_value)
to detect when a CPU has no more RUNNABLE clamped tasks and to flag this
condition.
Don't track any minimum utilization clamps since an idle CPU never
requires a minimum frequency. The decay of the blocked utilization is
good enough to reduce the CPU frequency.
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/20190621084217.8167-4-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Because of bucketization, different task-specific clamp values are
tracked in the same bucket. For example, with 20% bucket size and
assuming to have:
Task1: util_min=25%
Task2: util_min=35%
both tasks will be refcounted in the [20..39]% bucket and always boosted
only up to 20% thus implementing a simple floor aggregation normally
used in histograms.
In systems with only few and well-defined clamp values, it would be
useful to track the exact clamp value required by a task whenever
possible. For example, if a system requires only 23% and 47% boost
values then it's possible to track the exact boost required by each
task using only 3 buckets of ~33% size each.
Introduce a mechanism to max aggregate the requested clamp values of
RUNNABLE tasks in the same bucket. Keep it simple by resetting the
bucket value to its base value only when a bucket becomes inactive.
Allow a limited and controlled overboosting margin for tasks recounted
in the same bucket.
In systems where the boost values are not known in advance, it is still
possible to control the maximum acceptable overboosting margin by tuning
the number of clamp groups. For example, 20 groups ensure a 5% maximum
overboost.
Remove the rq bucket initialization code since a correct bucket value
is now computed when a task is refcounted into a CPU's rq.
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/20190621084217.8167-3-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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>
The term 'weighted' is not needed since there is no 'unweighted' load.
Instead use the term 'runnable' to distinguish 'runnable' load
(avg.runnable_load_avg) used in load balance from load (avg.load_avg)
which is the sum of 'runnable' and 'blocked' load.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/57f27a7f-2775-d832-e965-0f4d51bb1954@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So that external modules can hook into them and extract the info they
need. Since these new tracepoints have no events associated with them
exporting these tracepoints make them useful for external modules to
perform testing and debugging. There's no other way otherwise to access
them.
BPF doesn't have infrastructure to access these bare tracepoints either.
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/20190604111459.2862-7-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The new tracepoint allows us to track the changes in overutilized
status.
Overutilized status is associated with EAS. It indicates that the system
is in high performance state. EAS is disabled when the system is in this
state since there's not much energy savings while high performance tasks
are pushing the system to the limit and it's better to default to the
spreading behavior of the scheduler.
This tracepoint helps understanding and debugging the conditions under
which this happens.
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/20190604111459.2862-6-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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>
Remove the #ifdef CONFIG_SCHED_DEBUG.
Some of the tracepoints to be introduced in later patches need to access
this function. Hence make it always available since the tracepoints are
not protected by CONFIG_SCHED_DEBUG.
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/20190604111459.2862-2-qais.yousef@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Statements in the loop's body and before it are identical.
Use do-while to not repeat it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.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/43ffea6ee2152b90dedf962eac851609e4197218.1560256112.git.asml.silence@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
perf_event_open() limits the sample_period to 63 bits. See:
0819b2e30c ("perf: Limit perf_event_attr::sample_period to 63 bits")
Make ioctl() consistent with it.
Also on PowerPC, negative sample_period could cause a recursive
PMIs leading to a hang (reported when running perf-fuzzer).
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: acme@kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: maddy@linux.vnet.ibm.com
Cc: mpe@ellerman.id.au
Fixes: 0819b2e30c ("perf: Limit perf_event_attr::sample_period to 63 bits")
Link: https://lkml.kernel.org/r/20190604042953.914-1-ravi.bangoria@linux.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 1dc9285184 ("bpf: kernel side support for BTF Var and DataSec")
added invocations of btf_type_is_resolve_source_only before
btf_type_nosize_or_null which checks for the NULL pointer.
Swap the order of btf_type_nosize_or_null and
btf_type_is_resolve_source_only to make sure the do the NULL pointer
check first.
Fixes: 1dc9285184 ("bpf: kernel side support for BTF Var and DataSec")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Give userspace a cheap and reliable way to tell whether CLONE_PIDFD is
supported by the kernel or not. The easiest way is to pass an invalid
file descriptor value in parent_tidptr, perform the syscall and verify
that parent_tidptr has been changed to a valid file descriptor value.
CLONE_PIDFD uses parent_tidptr to return pidfds. CLONE_PARENT_SETTID
will use parent_tidptr to return the tid of the parent. The two flags
cannot be used together. Old kernels that only support
CLONE_PARENT_SETTID will not verify the value pointed to by
parent_tidptr. This behavior is unchanged even with the introduction of
CLONE_PIDFD.
However, if CLONE_PIDFD is specified the kernel will currently check the
value pointed to by parent_tidptr before placing the pidfd in the memory
pointed to. EINVAL will be returned if the value in parent_tidptr is not
0.
If CLONE_PIDFD is supported and fd 0 is closed, then the returned pidfd
can and likely will be 0 and parent_tidptr will be unchanged. This means
userspace must either check CLONE_PIDFD support beforehand or check that
fd 0 is not closed when invoking CLONE_PIDFD.
The check for pidfd == 0 was introduced during the v5.2 merge window by
commit b3e5838252 ("clone: add CLONE_PIDFD") to ensure that
CLONE_PIDFD could be potentially extended by passing in flags through
the return argument.
However, that extension would look horrible, and with the upcoming
introduction of the clone3 syscall in v5.3 there is no need to extend
legacy clone syscall this way. (Even if it would need to be extended,
CLONE_DETACHED can be reused with CLONE_PIDFD.)
So remove the pidfd == 0 check. Userspace that needs to be portable to
kernels without CLONE_PIDFD support can then be advised to initialize
pidfd to -1 and check the pidfd value returned by CLONE_PIDFD.
Fixes: b3e5838252 ("clone: add CLONE_PIDFD")
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Christian Brauner <christian@brauner.io>
Some archs like ARM store unwind information for .exit.text in sections
with unusual names. As this unwind information refers to .exit.text, it
must not be loaded when .exit.text is not loaded (when CONFIG_MODULE_UNLOAD
is unset); otherwise, loading a module can fail due to relocation failures.
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
The return value is fixed. Remove it and amend the callers.
[ tglx: Fixup arm/bL_switcher and powerpc/rtas ]
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20190613064813.8102-2-namit@vmware.com
cfd_data is marked as shared, but although it hold pointers to shared
data structures, it is private per core.
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rik van Riel <riel@surriel.com>
Link: https://lkml.kernel.org/r/20190613064813.8102-8-namit@vmware.com
The new generic VDSO library allows to unify the update_vsyscall[_tz]()
implementations.
Provide a generic implementation based on the x86 code and the bindings
which need to be implemented in architecture specific code.
[ tglx: Moved it into kernel/time where it belongs. Removed the pointless
line breaks in the stub functions. Massaged changelog ]
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Shijith Thotton <sthotton@marvell.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Huw Davies <huw@codeweavers.com>
Link: https://lkml.kernel.org/r/20190621095252.32307-4-vincenzo.frascino@arm.com
itimer_delete() uses spin_lock_irqsave() to obtain a `flags' variable
which can then be passed to unlock_timer(). It uses already spin_lock
locking for the structure instead of lock_timer() because it has a timer
which can not be removed by others at this point. The cleanup is always
performed with enabled interrupts.
Use spin_lock_irq() / spin_unlock_irq() so the `flags' variable can be
removed.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190621143643.25649-3-bigeasy@linutronix.de
itimer_delete() is invoked during do_exit(). At this point it is the
last thread in the group dying and doing the clean up.
Since it is the last thread in the group, there can not be any other
task attempting to lock the itimer which means the NULL assignment (which
avoids lookups in __lock_timer()) is not required.
The assignment and comment was copied in commit 0e568881178ff ("[PATCH]
fix posix-timers to have proper per-process scope") from
sys_timer_delete() which was/is the syscall interface and requires the
assignment.
Remove the superfluous ->it_signal = NULL assignment.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190621143643.25649-2-bigeasy@linutronix.de
This makes boot uniformly boottime and tai uniformly clocktai, to
address the remaining oversights.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lkml.kernel.org/r/20190621203249.3909-2-Jason@zx2c4.com
While this doesn't actually amount to a real difference, since the macro
evaluates to the same thing, every place else operates on ktime_t using
these functions, so let's not break the pattern.
Fixes: e3ff9c3678 ("timekeeping: Repair ktime_get_coarse*() granularity")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lkml.kernel.org/r/20190621203249.3909-1-Jason@zx2c4.com
Don't allow the TAI-UTC offset of the system clock to be set by adjtimex()
to a value larger than 100000 seconds.
This prevents an overflow in the conversion to int, prevents the CLOCK_TAI
clock from getting too far ahead of the CLOCK_REALTIME clock, and it is
still large enough to allow leap seconds to be inserted at the maximum rate
currently supported by the kernel (once per day) for the next ~270 years,
however unlikely it is that someone can survive a catastrophic event which
slowed down the rotation of the Earth so much.
Reported-by: Weikang shi <swkhack@gmail.com>
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Link: https://lkml.kernel.org/r/20190618154713.20929-1-mlichvar@redhat.com
Another round of SPDX updates for 5.2-rc6
Here is what I am guessing is going to be the last "big" SPDX update for
5.2. It contains all of the remaining GPLv2 and GPLv2+ updates that
were "easy" to determine by pattern matching. The ones after this are
going to be a bit more difficult and the people on the spdx list will be
discussing them on a case-by-case basis now.
Another 5000+ files are fixed up, so our overall totals are:
Files checked: 64545
Files with SPDX: 45529
Compared to the 5.1 kernel which was:
Files checked: 63848
Files with SPDX: 22576
This is a huge improvement.
Also, we deleted another 20000 lines of boilerplate license crud, always
nice to see in a diffstat.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'spdx-5.2-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx
Pull still more SPDX updates from Greg KH:
"Another round of SPDX updates for 5.2-rc6
Here is what I am guessing is going to be the last "big" SPDX update
for 5.2. It contains all of the remaining GPLv2 and GPLv2+ updates
that were "easy" to determine by pattern matching. The ones after this
are going to be a bit more difficult and the people on the spdx list
will be discussing them on a case-by-case basis now.
Another 5000+ files are fixed up, so our overall totals are:
Files checked: 64545
Files with SPDX: 45529
Compared to the 5.1 kernel which was:
Files checked: 63848
Files with SPDX: 22576
This is a huge improvement.
Also, we deleted another 20000 lines of boilerplate license crud,
always nice to see in a diffstat"
* tag 'spdx-5.2-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx: (65 commits)
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 507
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 506
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 505
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 504
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 503
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 502
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 501
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 499
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 498
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 497
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 496
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 495
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 491
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 490
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 489
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 488
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 487
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 486
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 485
...
In the presence of any form of instrumentation, nmi_enter() should be
done before calling any traceable code and any instrumentation code.
Currently, nmi_enter() is done in handle_domain_nmi(), which is much
too late as instrumentation code might get called before. Move the
nmi_enter/exit() calls to the arch IRQ vector handler.
On arm64, it is not possible to know if the IRQ vector handler was
called because of an NMI before acknowledging the interrupt. However, It
is possible to know whether normal interrupts could be taken in the
interrupted context (i.e. if taking an NMI in that context could
introduce a potential race condition).
When interrupting a context with IRQs disabled, call nmi_enter() as soon
as possible. In contexts with IRQs enabled, defer this to the interrupt
controller, which is in a better position to know if an interrupt taken
is an NMI.
Fixes: bc3c03ccb4 ("arm64: Enable the support of pseudo-NMIs")
Cc: <stable@vger.kernel.org> # 5.1.x-
Cc: Will Deacon <will.deacon@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The bfq schedule now uses css_next_descendant_pre directly after
the stats functionality depending on it has been from the core
blk-cgroup code to bfq. Export the symbol so that bfq can still
be build modular.
Fixes: d6258980da ("bfq-iosched: move bfq_stat_recursive_sum into the only caller")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This cleanly handles arches who do not yet define clone3.
clone3() was initially placed under __ARCH_WANT_SYS_CLONE under the
assumption that this would cleanly handle all architectures. It does
not.
Architectures such as nios2 or h8300 simply take the asm-generic syscall
definitions and generate their syscall table from it. Since they don't
define __ARCH_WANT_SYS_CLONE the build would fail complaining about
sys_clone3 missing. The reason this doesn't happen for legacy clone is
that nios2 and h8300 provide assembly stubs for sys_clone. This seems to
be done for architectural reasons.
The build failures for nios2 and h8300 were caught int -next luckily.
The solution is to define __ARCH_WANT_SYS_CLONE3 that architectures can
add. Additionally, we need a cond_syscall(clone3) for architectures such
as nios2 or h8300 that generate their syscall table in the way I
explained above.
Fixes: 8f3220a806 ("arch: wire-up clone3() syscall")
Signed-off-by: Christian Brauner <christian@brauner.io>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Adrian Reber <adrian@lisas.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: x86@kernel.org
WARN_ON_ONCE() could not be called safely under rq lock because
of console deadlock issues. Moreover WARN_ON_ONCE() is superfluous in
klp_check_stack(), because stack_trace_save_tsk_reliable() cannot return
-ENOSYS thanks to klp_have_reliable_stack() check in
klp_try_switch_task().
[ mbenes: changelog edited ]
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
This reverts commit 1d98a69e5c. Commit
31adf2308f ("livepatch: Convert error about unsupported reliable
stacktrace into a warning") weakened the enforcement for architectures
to have reliable stack traces support. The system only warns now about
it.
It only makes sense to reintroduce the compile time checking in
klp_try_switch_task() again and bail out early.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Recent rework of stack trace infrastructure introduced a new set of
helpers for common stack trace operations (commit e9b98e162a
("stacktrace: Provide helpers for common stack trace operations") and
related). As a result, save_stack_trace_tsk_reliable() is not directly
called anywhere. Livepatch, currently the only user of the reliable
stack trace feature, now calls stack_trace_save_tsk_reliable().
When CONFIG_HAVE_RELIABLE_STACKTRACE is set and depending on
CONFIG_ARCH_STACKWALK, stack_trace_save_tsk_reliable() calls either
arch_stack_walk_reliable() or mentioned save_stack_trace_tsk_reliable().
x86_64 defines the former, ppc64le the latter. All other architectures
do not have HAVE_RELIABLE_STACKTRACE and include/linux/stacktrace.h
defines -ENOSYS returning version for them.
In short, stack_trace_save_tsk_reliable() returning -ENOSYS defined in
include/linux/stacktrace.h serves the same purpose as the old weak
version of save_stack_trace_tsk_reliable() which is therefore no longer
needed.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Alexei Starovoitov says:
====================
pull-request: bpf-next 2019-06-19
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) new SO_REUSEPORT_DETACH_BPF setsocktopt, from Martin.
2) BTF based map definition, from Andrii.
3) support bpf_map_lookup_elem for xskmap, from Jonathan.
4) bounded loops and scalar precision logic in the verifier, from Alexei.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
When converting an xdp_frame into an SKB, and sending this into the network
stack, then the underlying XDP memory model need to release associated
resources, because the network stack don't have callbacks for XDP memory
models. The only memory model that needs this is page_pool, when a driver
use the DMA-mapping feature.
Introduce page_pool_release_page(), which basically does the same as
page_pool_unmap_page(). Add xdp_release_frame() as the XDP memory model
interface for calling it, if the memory model match MEM_TYPE_PAGE_POOL, to
save the function call overhead for others. Have cpumap call
xdp_release_frame() before xdp_scrub_frame().
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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>
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Based on 1 normalized pattern(s):
this file is subject to the terms and conditions of version 2 of the
gnu general public license see the file copying in the main
directory of the linux distribution for more details
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 5 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081200.872755311@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Based on 1 normalized pattern(s):
this file is released under the gpl v2
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 3 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204655.103854853@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Based on 2 normalized pattern(s):
this source code is licensed under the gnu general public license
version 2 see the file copying for more details
this source code is licensed under general public license version 2
see
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 52 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.449021192@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On architectures that have a larger dma_addr_t than phys_addr_t,
the swiotlb_tbl_map_single() function truncates its return code
in the failure path, making it impossible to identify the error
later, as we compare to the original value:
kernel/dma/swiotlb.c:551:9: error: implicit conversion from 'dma_addr_t' (aka 'unsigned long long') to 'phys_addr_t' (aka 'unsigned int') changes value from 18446744073709551615 to 4294967295 [-Werror,-Wconstant-conversion]
return DMA_MAPPING_ERROR;
Use an explicit typecast here to convert it to the narrower type,
and use the same expression in the error handling later.
Fixes: b907e20508 ("swiotlb: remove SWIOTLB_MAP_ERROR")
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The name of pm_suspend_via_s2idle() is confusing, as it doesn't
reflect the purpose of the function precisely enough and it is
very similar to pm_suspend_via_firmware(), which has a different
purpose, so rename it as pm_suspend_default_s2idle() and update
its only caller, i8042_register_ports(), accordingly.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Introduce precision tracking logic that
helps cilium programs the most:
old clang old clang new clang new clang
with all patches with all patches
bpf_lb-DLB_L3.o 1838 2283 1923 1863
bpf_lb-DLB_L4.o 3218 2657 3077 2468
bpf_lb-DUNKNOWN.o 1064 545 1062 544
bpf_lxc-DDROP_ALL.o 26935 23045 166729 22629
bpf_lxc-DUNKNOWN.o 34439 35240 174607 28805
bpf_netdev.o 9721 8753 8407 6801
bpf_overlay.o 6184 7901 5420 4754
bpf_lxc_jit.o 39389 50925 39389 50925
Consider code:
654: (85) call bpf_get_hash_recalc#34
655: (bf) r7 = r0
656: (15) if r8 == 0x0 goto pc+29
657: (bf) r2 = r10
658: (07) r2 += -48
659: (18) r1 = 0xffff8881e41e1b00
661: (85) call bpf_map_lookup_elem#1
662: (15) if r0 == 0x0 goto pc+23
663: (69) r1 = *(u16 *)(r0 +0)
664: (15) if r1 == 0x0 goto pc+21
665: (bf) r8 = r7
666: (57) r8 &= 65535
667: (bf) r2 = r8
668: (3f) r2 /= r1
669: (2f) r2 *= r1
670: (bf) r1 = r8
671: (1f) r1 -= r2
672: (57) r1 &= 255
673: (25) if r1 > 0x1e goto pc+12
R0=map_value(id=0,off=0,ks=20,vs=64,imm=0) R1_w=inv(id=0,umax_value=30,var_off=(0x0; 0x1f))
674: (67) r1 <<= 1
675: (0f) r0 += r1
At this point the verifier will notice that scalar R1 is used in map pointer adjustment.
R1 has to be precise for later operations on R0 to be validated properly.
The verifier will backtrack the above code in the following way:
last_idx 675 first_idx 664
regs=2 stack=0 before 675: (0f) r0 += r1 // started backtracking R1 regs=2 is a bitmask
regs=2 stack=0 before 674: (67) r1 <<= 1
regs=2 stack=0 before 673: (25) if r1 > 0x1e goto pc+12
regs=2 stack=0 before 672: (57) r1 &= 255
regs=2 stack=0 before 671: (1f) r1 -= r2 // now both R1 and R2 has to be precise -> regs=6 mask
regs=6 stack=0 before 670: (bf) r1 = r8 // after this insn R8 and R2 has to be precise
regs=104 stack=0 before 669: (2f) r2 *= r1 // after this one R8, R2, and R1
regs=106 stack=0 before 668: (3f) r2 /= r1
regs=106 stack=0 before 667: (bf) r2 = r8
regs=102 stack=0 before 666: (57) r8 &= 65535
regs=102 stack=0 before 665: (bf) r8 = r7
regs=82 stack=0 before 664: (15) if r1 == 0x0 goto pc+21
// this is the end of verifier state. The following regs will be marked precised:
R1_rw=invP(id=0,umax_value=65535,var_off=(0x0; 0xffff)) R7_rw=invP(id=0)
parent didn't have regs=82 stack=0 marks // so backtracking continues into parent state
last_idx 663 first_idx 655
regs=82 stack=0 before 663: (69) r1 = *(u16 *)(r0 +0) // R1 was assigned no need to track it further
regs=80 stack=0 before 662: (15) if r0 == 0x0 goto pc+23 // keep tracking R7
regs=80 stack=0 before 661: (85) call bpf_map_lookup_elem#1 // keep tracking R7
regs=80 stack=0 before 659: (18) r1 = 0xffff8881e41e1b00
regs=80 stack=0 before 658: (07) r2 += -48
regs=80 stack=0 before 657: (bf) r2 = r10
regs=80 stack=0 before 656: (15) if r8 == 0x0 goto pc+29
regs=80 stack=0 before 655: (bf) r7 = r0 // here the assignment into R7
// mark R0 to be precise:
R0_rw=invP(id=0)
parent didn't have regs=1 stack=0 marks // regs=1 -> tracking R0
last_idx 654 first_idx 644
regs=1 stack=0 before 654: (85) call bpf_get_hash_recalc#34 // and in the parent frame it was a return value
// nothing further to backtrack
Two scalar registers not marked precise are equivalent from state pruning point of view.
More details in the patch comments.
It doesn't support bpf2bpf calls yet and enabled for root only.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The commit 7640ead939 partially resolved the issue of callees
incorrectly pruning the callers.
With introduction of bounded loops and jmps_processed heuristic
single verifier state may contain multiple branches and calls.
It's possible that new verifier state (for future pruning) will be
allocated inside callee. Then callee will exit (still within the same
verifier state). It will go back to the caller and there R6-R9 registers
will be read and will trigger mark_reg_read. But the reg->live for all frames
but the top frame is not set to LIVE_NONE. Hence mark_reg_read will fail
to propagate liveness into parent and future walking will incorrectly
conclude that the states are equivalent because LIVE_READ is not set.
In other words the rule for parent/live should be:
whenever register parentage chain is set the reg->live should be set to LIVE_NONE.
is_state_visited logic already follows this rule for spilled registers.
Fixes: 7640ead939 ("bpf: verifier: make sure callees don't prune with caller differences")
Fixes: f4d7e40a5b ("bpf: introduce function calls (verification)")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Allow the verifier to validate the loops by simulating their execution.
Exisiting programs have used '#pragma unroll' to unroll the loops
by the compiler. Instead let the verifier simulate all iterations
of the loop.
In order to do that introduce parentage chain of bpf_verifier_state and
'branches' counter for the number of branches left to explore.
See more detailed algorithm description in bpf_verifier.h
This algorithm borrows the key idea from Edward Cree approach:
https://patchwork.ozlabs.org/patch/877222/
Additional state pruning heuristics make such brute force loop walk
practical even for large loops.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch extends is_branch_taken() logic from JMP+K instructions
to JMP+X instructions.
Conditional branches are often done when src and dst registers
contain known scalars. In such case the verifier can follow
the branch that is going to be taken when program executes.
That speeds up the verification and is essential feature to support
bounded loops.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Compilers often spill induction variables into the stack,
hence it is necessary for the verifier to track scalar values
of the registers through stack slots.
Also few bpf programs were incorrectly rejected in the past,
since the verifier was not able to track such constants while
they were used to compute offsets into packet headers.
Tracking constants through the stack significantly decreases
the chances of state pruning, since two different constants
are considered to be different by state equivalency.
End result that cilium tests suffer serious degradation in the number
of states processed and corresponding verification time increase.
before after
bpf_lb-DLB_L3.o 1838 6441
bpf_lb-DLB_L4.o 3218 5908
bpf_lb-DUNKNOWN.o 1064 1064
bpf_lxc-DDROP_ALL.o 26935 93790
bpf_lxc-DUNKNOWN.o 34439 123886
bpf_netdev.o 9721 31413
bpf_overlay.o 6184 18561
bpf_lxc_jit.o 39389 359445
After further debugging turned out that cillium progs are
getting hurt by clang due to the same constant tracking issue.
Newer clang generates better code by spilling less to the stack.
Instead it keeps more constants in the registers which
hurts state pruning since the verifier already tracks constants
in the registers:
old clang new clang
(no spill/fill tracking introduced by this patch)
bpf_lb-DLB_L3.o 1838 1923
bpf_lb-DLB_L4.o 3218 3077
bpf_lb-DUNKNOWN.o 1064 1062
bpf_lxc-DDROP_ALL.o 26935 166729
bpf_lxc-DUNKNOWN.o 34439 174607
bpf_netdev.o 9721 8407
bpf_overlay.o 6184 5420
bpf_lcx_jit.o 39389 39389
The final table is depressing:
old clang old clang new clang new clang
const spill/fill const spill/fill
bpf_lb-DLB_L3.o 1838 6441 1923 8128
bpf_lb-DLB_L4.o 3218 5908 3077 6707
bpf_lb-DUNKNOWN.o 1064 1064 1062 1062
bpf_lxc-DDROP_ALL.o 26935 93790 166729 380712
bpf_lxc-DUNKNOWN.o 34439 123886 174607 440652
bpf_netdev.o 9721 31413 8407 31904
bpf_overlay.o 6184 18561 5420 23569
bpf_lxc_jit.o 39389 359445 39389 359445
Tracking constants in the registers hurts state pruning already.
Adding tracking of constants through stack hurts pruning even more.
The later patch address this general constant tracking issue
with coarse/precise logic.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:
struct tp_probes {
...
struct tracepoint_func probes[0];
};
instance = kmalloc(sizeof(sizeof(struct tp_probes) +
sizeof(struct tracepoint_func) * count, GFP_KERNEL);
Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:
instance = kmalloc(struct_size(instance, probes, count) GFP_KERNEL);
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pull networking fixes from David Miller:
"Lots of bug fixes here:
1) Out of bounds access in __bpf_skc_lookup, from Lorenz Bauer.
2) Fix rate reporting in cfg80211_calculate_bitrate_he(), from John
Crispin.
3) Use after free in psock backlog workqueue, from John Fastabend.
4) Fix source port matching in fdb peer flow rule of mlx5, from Raed
Salem.
5) Use atomic_inc_not_zero() in fl6_sock_lookup(), from Eric Dumazet.
6) Network header needs to be set for packet redirect in nfp, from
John Hurley.
7) Fix udp zerocopy refcnt, from Willem de Bruijn.
8) Don't assume linear buffers in vxlan and geneve error handlers,
from Stefano Brivio.
9) Fix TOS matching in mlxsw, from Jiri Pirko.
10) More SCTP cookie memory leak fixes, from Neil Horman.
11) Fix VLAN filtering in rtl8366, from Linus Walluij.
12) Various TCP SACK payload size and fragmentation memory limit fixes
from Eric Dumazet.
13) Use after free in pneigh_get_next(), also from Eric Dumazet.
14) LAPB control block leak fix from Jeremy Sowden"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (145 commits)
lapb: fixed leak of control-blocks.
tipc: purge deferredq list for each grp member in tipc_group_delete
ax25: fix inconsistent lock state in ax25_destroy_timer
neigh: fix use-after-free read in pneigh_get_next
tcp: fix compile error if !CONFIG_SYSCTL
hv_sock: Suppress bogus "may be used uninitialized" warnings
be2net: Fix number of Rx queues used for flow hashing
net: handle 802.1P vlan 0 packets properly
tcp: enforce tcp_min_snd_mss in tcp_mtu_probing()
tcp: add tcp_min_snd_mss sysctl
tcp: tcp_fragment() should apply sane memory limits
tcp: limit payload size of sacked skbs
Revert "net: phylink: set the autoneg state in phylink_phy_change"
bpf: fix nested bpf tracepoints with per-cpu data
bpf: Fix out of bounds memory access in bpf_sk_storage
vsock/virtio: set SOCK_DONE on peer shutdown
net: dsa: rtl8366: Fix up VLAN filtering
net: phylink: set the autoneg state in phylink_phy_change
net: add high_order_alloc_disable sysctl/static key
tcp: add tcp_tx_skb_cache sysctl
...
Nadav reported that code-gen changed because of the this_cpu_*()
constraints, avoid this for select_idle_cpu() because that runs with
preemption (and IRQs) disabled anyway.
Reported-by: Nadav Amit <nadav.amit@gmail.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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The upper bits of the count field is used as reader count. When
sufficient number of active readers are present, the most significant
bit will be set and the count becomes negative. If the number of active
readers keep on piling up, we may eventually overflow the reader counts.
This is not likely to happen unless the number of bits reserved for
reader count is reduced because those bits are need for other purpose.
To prevent this count overflow from happening, the most significant
bit is now treated as a guard bit (RWSEM_FLAG_READFAIL). Read-lock
attempts will now fail for both the fast and slow paths whenever this
bit is set. So all those extra readers will be put to sleep in the wait
list. Wakeup will not happen until the reader count reaches 0.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-17-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reader optimistic spinning is helpful when the reader critical section
is short and there aren't that many readers around. It makes readers
relatively more preferred than writers. When a writer times out spinning
on a reader-owned lock and set the nospinnable bits, there are two main
reasons for that.
1) The reader critical section is long, perhaps the task sleeps after
acquiring the read lock.
2) There are just too many readers contending the lock causing it to
take a while to service all of them.
In the former case, long reader critical section will impede the progress
of writers which is usually more important for system performance.
In the later case, reader optimistic spinning tends to make the reader
groups that contain readers that acquire the lock together smaller
leading to more of them. That may hurt performance in some cases. In
other words, the setting of nonspinnable bits indicates that reader
optimistic spinning may not be helpful for those workloads that cause it.
Therefore, any writers that have observed the setting of the writer
nonspinnable bit for a given rwsem after they fail to acquire the lock
via optimistic spinning will set the reader nonspinnable bit once they
acquire the write lock. Similarly, readers that observe the setting
of reader nonspinnable bit at slowpath entry will also set the reader
nonspinnable bit when they acquire the read lock via the wakeup path.
Once the reader nonspinnable bit is on, it will only be reset when
a writer is able to acquire the rwsem in the fast path or somehow a
reader or writer in the slowpath doesn't observe the nonspinable bit.
This is to discourage reader optmistic spinning on that particular
rwsem and make writers more preferred. This adaptive disabling of reader
optimistic spinning will alleviate some of the negative side effect of
this feature.
In addition, this patch tries to make readers in the spinning queue
follow the phase-fair principle after quitting optimistic spinning
by checking if another reader has somehow acquired a read lock after
this reader enters the optimistic spinning queue. If so and the rwsem
is still reader-owned, this reader is in the right read-phase and can
attempt to acquire the lock.
On a 2-socket 40-core 80-thread Skylake system, the page_fault1 test of
the will-it-scale benchmark was run with various number of threads. The
number of operations done before reader optimistic spinning patches,
this patch and after this patch were:
Threads Before rspin Before patch After patch %change
------- ------------ ------------ ----------- -------
20 5541068 5345484 5455667 -3.5%/ +2.1%
40 10185150 7292313 9219276 -28.5%/+26.4%
60 8196733 6460517 7181209 -21.2%/+11.2%
80 9508864 6739559 8107025 -29.1%/+20.3%
This patch doesn't recover all the lost performance, but it is more
than half. Given the fact that reader optimistic spinning does benefit
some workloads, this is a good compromise.
Using the rwsem locking microbenchmark with very short critical section,
this patch doesn't have too much impact on locking performance as shown
by the locking rates (kops/s) below with equal numbers of readers and
writers before and after this patch:
# of Threads Pre-patch Post-patch
------------ --------- ----------
2 4,730 4,969
4 4,814 4,786
8 4,866 4,815
16 4,715 4,511
32 3,338 3,500
64 3,212 3,389
80 3,110 3,044
When running the locking microbenchmark with 40 dedicated reader and writer
threads, however, the reader performance is curtailed to favor the writer.
Before patch:
40 readers, Iterations Min/Mean/Max = 204,026/234,309/254,816
40 writers, Iterations Min/Mean/Max = 88,515/95,884/115,644
After patch:
40 readers, Iterations Min/Mean/Max = 33,813/35,260/36,791
40 writers, Iterations Min/Mean/Max = 95,368/96,565/97,798
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-16-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the rwsem is owned by reader, writers stop optimistic spinning
simply because there is no easy way to figure out if all the readers
are actively running or not. However, there are scenarios where
the readers are unlikely to sleep and optimistic spinning can help
performance.
This patch provides a simple mechanism for spinning on a reader-owned
rwsem by a writer. It is a time threshold based spinning where the
allowable spinning time can vary from 10us to 25us depending on the
condition of the rwsem.
When the time threshold is exceeded, the nonspinnable bits will be set
in the owner field to indicate that no more optimistic spinning will
be allowed on this rwsem until it becomes writer owned again. Not even
readers is allowed to acquire the reader-locked rwsem by optimistic
spinning for fairness.
We also want a writer to acquire the lock after the readers hold the
lock for a relatively long time. In order to give preference to writers
under such a circumstance, the single RWSEM_NONSPINNABLE bit is now split
into two - one for reader and one for writer. When optimistic spinning
is disabled, both bits will be set. When the reader count drop down
to 0, the writer nonspinnable bit will be cleared to allow writers to
spin on the lock, but not the readers. When a writer acquires the lock,
it will write its own task structure pointer into sem->owner and clear
the reader nonspinnable bit in the process.
The time taken for each iteration of the reader-owned rwsem spinning
loop varies. Below are sample minimum elapsed times for 16 iterations
of the loop.
System Time for 16 Iterations
------ ----------------------
1-socket Skylake ~800ns
4-socket Broadwell ~300ns
2-socket ThunderX2 (arm64) ~250ns
When the lock cacheline is contended, we can see up to almost 10X
increase in elapsed time. So 25us will be at most 500, 1300 and 1600
iterations for each of the above systems.
With a locking microbenchmark running on 5.1 based kernel, the total
locking rates (in kops/s) on a 8-socket IvyBridge-EX system with
equal numbers of readers and writers before and after this patch were
as follows:
# of Threads Pre-patch Post-patch
------------ --------- ----------
2 1,759 6,684
4 1,684 6,738
8 1,074 7,222
16 900 7,163
32 458 7,316
64 208 520
128 168 425
240 143 474
This patch gives a big boost in performance for mixed reader/writer
workloads.
With 32 locking threads, the rwsem lock event data were:
rwsem_opt_fail=79850
rwsem_opt_nospin=5069
rwsem_opt_rlock=597484
rwsem_opt_wlock=957339
rwsem_sleep_reader=57782
rwsem_sleep_writer=55663
With 64 locking threads, the data looked like:
rwsem_opt_fail=346723
rwsem_opt_nospin=6293
rwsem_opt_rlock=1127119
rwsem_opt_wlock=1400628
rwsem_sleep_reader=308201
rwsem_sleep_writer=72281
So a lot more threads acquired the lock in the slowpath and more threads
went to sleep.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-15-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The rwsem->owner contains not just the task structure pointer, it also
holds some flags for storing the current state of the rwsem. Some of
the flags may have to be atomically updated. To reflect the new reality,
the owner is now changed to an atomic_long_t type.
New helper functions are added to properly separate out the task
structure pointer and the embedded flags.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-14-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch enables readers to optimistically spin on a
rwsem when it is owned by a writer instead of going to sleep
directly. The rwsem_can_spin_on_owner() function is extracted
out of rwsem_optimistic_spin() and is called directly by
rwsem_down_read_slowpath() and rwsem_down_write_slowpath().
With a locking microbenchmark running on 5.1 based kernel, the total
locking rates (in kops/s) on a 8-socket IvyBrige-EX system with equal
numbers of readers and writers before and after the patch were as
follows:
# of Threads Pre-patch Post-patch
------------ --------- ----------
4 1,674 1,684
8 1,062 1,074
16 924 900
32 300 458
64 195 208
128 164 168
240 149 143
The performance change wasn't significant in this case, but this change
is required by a follow-on patch.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-13-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Bit 1 of sem->owner (RWSEM_ANONYMOUSLY_OWNED) is used to designate an
anonymous owner - readers or an anonymous writer. The setting of this
anonymous bit is used as an indicator that optimistic spinning cannot
be done on this rwsem.
With the upcoming reader optimistic spinning patches, a reader-owned
rwsem can be spinned on for a limit period of time. We still need
this bit to indicate a rwsem is nonspinnable, but not setting this
bit loses its meaning that the owner is known. So rename the bit
to RWSEM_NONSPINNABLE to clarify its meaning.
This patch also fixes a DEBUG_RWSEMS_WARN_ON() bug in __up_write().
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-12-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the front of the wait queue is a reader, other readers
immediately following the first reader will also be woken up at the
same time. However, if there is a writer in between. Those readers
behind the writer will not be woken up.
Because of optimistic spinning, the lock acquisition order is not FIFO
anyway. The lock handoff mechanism will ensure that lock starvation
will not happen.
Assuming that the lock hold times of the other readers still in the
queue will be about the same as the readers that are being woken up,
there is really not much additional cost other than the additional
latency due to the wakeup of additional tasks by the waker. Therefore
all the readers up to a maximum of 256 in the queue are woken up when
the first waiter is a reader to improve reader throughput. This is
somewhat similar in concept to a phase-fair R/W lock.
With a locking microbenchmark running on 5.1 based kernel, the total
locking rates (in kops/s) on a 8-socket IvyBridge-EX system with
equal numbers of readers and writers before and after this patch were
as follows:
# of Threads Pre-Patch Post-patch
------------ --------- ----------
4 1,641 1,674
8 731 1,062
16 564 924
32 78 300
64 38 195
240 50 149
There is no performance gain at low contention level. At high contention
level, however, this patch gives a pretty decent performance boost.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-11-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
An RT task can do optimistic spinning only if the lock holder is
actually running. If the state of the lock holder isn't known, there
is a possibility that high priority of the RT task may block forward
progress of the lock holder if it happens to reside on the same CPU.
This will lead to deadlock. So we have to make sure that an RT task
will not spin on a reader-owned rwsem.
When the owner is temporarily set to NULL, there are two cases
where we may want to continue spinning:
1) The lock owner is in the process of releasing the lock, sem->owner
is cleared but the lock has not been released yet.
2) The lock was free and owner cleared, but another task just comes
in and acquire the lock before we try to get it. The new owner may
be a spinnable writer.
So an RT task is now made to retry one more time to see if it can
acquire the lock or continue spinning on the new owning writer.
When testing on a 8-socket IvyBridge-EX system, the one additional retry
seems to improve locking performance of RT write locking threads under
heavy contentions. The table below shows the locking rates (in kops/s)
with various write locking threads before and after the patch.
Locking threads Pre-patch Post-patch
--------------- --------- -----------
4 2,753 2,608
8 2,529 2,520
16 1,727 1,918
32 1,263 1,956
64 889 1,343
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-10-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With the use of wake_q, we can do task wakeups without holding the
wait_lock. There is one exception in the rwsem code, though. It is
when the writer in the slowpath detects that there are waiters ahead
but the rwsem is not held by a writer. This can lead to a long wait_lock
hold time especially when a large number of readers are to be woken up.
Remediate this situation by releasing the wait_lock before waking
up tasks and re-acquiring it afterward. The rwsem_try_write_lock()
function is also modified to read the rwsem count directly to avoid
stale count value.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-9-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Because of writer lock stealing, it is possible that a constant
stream of incoming writers will cause a waiting writer or reader to
wait indefinitely leading to lock starvation.
This patch implements a lock handoff mechanism to disable lock stealing
and force lock handoff to the first waiter or waiters (for readers)
in the queue after at least a 4ms waiting period unless it is a RT
writer task which doesn't need to wait. The waiting period is used to
avoid discouraging lock stealing too much to affect performance.
The setting and clearing of the handoff bit is serialized by the
wait_lock. So racing is not possible.
A rwsem microbenchmark was run for 5 seconds on a 2-socket 40-core
80-thread Skylake system with a v5.1 based kernel and 240 write_lock
threads with 5us sleep critical section.
Before the patch, the min/mean/max numbers of locking operations for
the locking threads were 1/7,792/173,696. After the patch, the figures
became 5,842/6,542/7,458. It can be seen that the rwsem became much
more fair, though there was a drop of about 16% in the mean locking
operations done which was a tradeoff of having better fairness.
Making the waiter set the handoff bit right after the first wakeup can
impact performance especially with a mixed reader/writer workload. With
the same microbenchmark with short critical section and equal number of
reader and writer threads (40/40), the reader/writer locking operation
counts with the current patch were:
40 readers, Iterations Min/Mean/Max = 1,793/1,794/1,796
40 writers, Iterations Min/Mean/Max = 1,793/34,956/86,081
By making waiter set handoff bit immediately after wakeup:
40 readers, Iterations Min/Mean/Max = 43/44/46
40 writers, Iterations Min/Mean/Max = 43/1,263/3,191
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-8-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch modifies rwsem_spin_on_owner() to return four possible
values to better reflect the state of lock holder which enables us to
make a better decision of what to do next.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-7-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After merging all the relevant rwsem code into one single file, there
are a number of optimizations and cleanups that can be done:
1) Remove all the EXPORT_SYMBOL() calls for functions that are not
accessed elsewhere.
2) Remove all the __visible tags as none of the functions will be
called from assembly code anymore.
3) Make all the internal functions static.
4) Remove some unneeded blank lines.
5) Remove the intermediate rwsem_down_{read|write}_failed*() functions
and rename __rwsem_down_{read|write}_failed_common() to
rwsem_down_{read|write}_slowpath().
6) Remove "__" prefix of __rwsem_mark_wake().
7) Use atomic_long_try_cmpxchg_acquire() as much as possible.
8) Remove the rwsem_rtrylock and rwsem_wtrylock lock events as they
are not that useful.
That enables the compiler to do better optimization and reduce code
size. The text+data size of rwsem.o on an x86-64 machine with gcc8 was
reduced from 10237 bytes to 5030 bytes with this change.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-6-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now we only have one implementation of rwsem. Even though we still use
xadd to handle reader locking, we use cmpxchg for writer instead. So
the filename rwsem-xadd.c is not strictly correct. Also no one outside
of the rwsem code need to know the internal implementation other than
function prototypes for two internal functions that are called directly
from percpu-rwsem.c.
So the rwsem-xadd.c and rwsem.h files are now merged into rwsem.c in
the following order:
<upper part of rwsem.h>
<rwsem-xadd.c>
<lower part of rwsem.h>
<rwsem.c>
The rwsem.h file now contains only 2 function declarations for
__up_read() and __down_read().
This is a code relocation patch with no code change at all except
making __up_read() and __down_read() non-static functions so they
can be used by percpu-rwsem.c.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-5-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The current way of using various reader, writer and waiting biases
in the rwsem code are confusing and hard to understand. I have to
reread the rwsem count guide in the rwsem-xadd.c file from time to
time to remind myself how this whole thing works. It also makes the
rwsem code harder to be optimized.
To make rwsem more sane, a new locking scheme similar to the one in
qrwlock is now being used. The atomic long count has the following
bit definitions:
Bit 0 - writer locked bit
Bit 1 - waiters present bit
Bits 2-7 - reserved for future extension
Bits 8-X - reader count (24/56 bits)
The cmpxchg instruction is now used to acquire the write lock. The read
lock is still acquired with xadd instruction, so there is no change here.
This scheme will allow up to 16M/64P active readers which should be
more than enough. We can always use some more reserved bits if necessary.
With that change, we can deterministically know if a rwsem has been
write-locked. Looking at the count alone, however, one cannot determine
for certain if a rwsem is owned by readers or not as the readers that
set the reader count bits may be in the process of backing out. So we
still need the reader-owned bit in the owner field to be sure.
With a locking microbenchmark running on 5.1 based kernel, the total
locking rates (in kops/s) of the benchmark on a 8-socket 120-core
IvyBridge-EX system before and after the patch were as follows:
Before Patch After Patch
# of Threads wlock rlock wlock rlock
------------ ----- ----- ----- -----
1 30,659 31,341 31,055 31,283
2 8,909 16,457 9,884 17,659
4 9,028 15,823 8,933 20,233
8 8,410 14,212 7,230 17,140
16 8,217 25,240 7,479 24,607
The locking rates of the benchmark on a Power8 system were as follows:
Before Patch After Patch
# of Threads wlock rlock wlock rlock
------------ ----- ----- ----- -----
1 12,963 13,647 13,275 13,601
2 7,570 11,569 7,902 10,829
4 5,232 5,516 5,466 5,435
8 5,233 3,386 5,467 3,168
The locking rates of the benchmark on a 2-socket ARM64 system were
as follows:
Before Patch After Patch
# of Threads wlock rlock wlock rlock
------------ ----- ----- ----- -----
1 21,495 21,046 21,524 21,074
2 5,293 10,502 5,333 10,504
4 5,325 11,463 5,358 11,631
8 5,391 11,712 5,470 11,680
The performance are roughly the same before and after the patch. There
are run-to-run variations in performance. Runs with higher variances
usually have higher throughput.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-4-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After the following commit:
59aabfc7e9 ("locking/rwsem: Reduce spinlock contention in wakeup after up_read()/up_write()")
the rwsem_wake() forgoes doing a wakeup if the wait_lock cannot be directly
acquired and an optimistic spinning locker is present. This can help performance
by avoiding spinning on the wait_lock when it is contended.
With the later commit:
133e89ef5e ("locking/rwsem: Enable lockless waiter wakeup(s)")
the performance advantage of the above optimization diminishes as the average
wait_lock hold time become much shorter.
With a later patch that supports rwsem lock handoff, we can no
longer relies on the fact that the presence of an optimistic spinning
locker will ensure that the lock will be acquired by a task soon and
rwsem_wake() will be called later on to wake up waiters. This can lead
to missed wakeup and application hang.
So the original 59aabfc7e9 commit has to be reverted.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-3-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The owner field in the rw_semaphore structure is used primarily for
optimistic spinning. However, identifying the rwsem owner can also be
helpful in debugging as well as tracing locking related issues when
analyzing crash dump. The owner field may also store state information
that can be important to the operation of the rwsem.
So the owner field is now made a permanent member of the rw_semaphore
structure irrespective of CONFIG_RWSEM_SPIN_ON_OWNER.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-2-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a cfs_rq sleeps and returns its quota, we delay for 5ms before
waking any throttled cfs_rqs to coalesce with other cfs_rqs going to
sleep, as this has to be done outside of the rq lock we hold.
The current code waits for 5ms without any sleeps, instead of waiting
for 5ms from the first sleep, which can delay the unthrottle more than
we want. Switch this around so that we can't push this forward forever.
This requires an extra flag rather than using hrtimer_active, since we
need to start a new timer if the current one is in the process of
finishing.
Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Xunlei Pang <xlpang@linux.alibaba.com>
Acked-by: Phil Auld <pauld@redhat.com>
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/xm26a7euy6iq.fsf_-_@bsegall-linux.svl.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Jens reported that significant performance can be had on some block
workloads by special casing local wakeups. That is, wakeups on the
current task before it schedules out.
Given something like the normal wait pattern:
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (cond)
break;
schedule();
}
__set_current_state(TASK_RUNNING);
Any wakeup (on this CPU) after set_current_state() and before
schedule() would benefit from this.
Normal wakeups take p->pi_lock, which serializes wakeups to the same
task. By eliding that we gain concurrency on:
- ttwu_stat(); we already had concurrency on rq stats, this now also
brings it to task stats. -ENOCARE
- tracepoints; it is now possible to get multiple instances of
trace_sched_waking() (and possibly trace_sched_wakeup()) for the
same task. Tracers will have to learn to cope.
Furthermore, p->pi_lock is used by set_special_state(), to order
against TASK_RUNNING stores from other CPUs. But since this is
strictly CPU local, we don't need the lock, and set_special_state()'s
disabling of IRQs is sufficient.
After the normal wakeup takes p->pi_lock it issues
smp_mb__after_spinlock(), in order to ensure the woken task must
observe prior stores before we observe the p->state. If this is CPU
local, this will be satisfied with a compiler barrier, and we rely on
try_to_wake_up() being a funcation call, which implies such.
Since, when 'p == current', 'p->on_rq' must be true, the normal wakeup
would continue into the ttwu_remote() branch, which normally is
concerned with exactly this wakeup scenario, except from a remote CPU.
IOW we're waking a task that is still running. In this case, we can
trivially avoid taking rq->lock, all that's left from this is to set
p->state.
This then yields an extremely simple and fast path for 'p == current'.
Reported-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: gkohli@codeaurora.org
Cc: hch@lst.de
Cc: oleg@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
runnable_avg_yN_inv[] is only used in kernel/sched/pelt.c but was
included in several other places because they need other macros all
came from kernel/sched/sched-pelt.h which was generated by
Documentation/scheduler/sched-pelt. As the result, it causes compilation
a lot of warnings,
kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but not used [-Wunused-const-variable=]
kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but not used [-Wunused-const-variable=]
kernel/sched/sched-pelt.h:4:18: warning: 'runnable_avg_yN_inv' defined but not used [-Wunused-const-variable=]
...
Silence it by appending the __maybe_unused attribute for it, so all
generated variables and macros can still be kept in the same file.
Signed-off-by: Qian Cai <cai@lca.pw>
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/1559596304-31581-1-git-send-email-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
cfs_rq_has_blocked() and others_have_blocked() are only used within
update_blocked_averages(). The !CONFIG_FAIR_GROUP_SCHED version of the
latter calls them within a #define CONFIG_NO_HZ_COMMON block, whereas
the CONFIG_FAIR_GROUP_SCHED one calls them unconditionnally.
As reported by Qian, the above leads to this warning in
!CONFIG_NO_HZ_COMMON configs:
kernel/sched/fair.c: In function 'update_blocked_averages':
kernel/sched/fair.c:7750:7: warning: variable 'done' set but not used [-Wunused-but-set-variable]
It wouldn't be wrong to keep cfs_rq_has_blocked() and
others_have_blocked() as they are, but since their only current use is
to figure out when we can stop calling update_blocked_averages() on
fully decayed NOHZ idle CPUs, we can give them a new definition for
!CONFIG_NO_HZ_COMMON.
Change the definition of cfs_rq_has_blocked() and
others_have_blocked() for !CONFIG_NO_HZ_COMMON so that the
NOHZ-specific blocks of update_blocked_averages() become no-ops and
the 'done' variable gets optimised out.
While at it, remove the CONFIG_NO_HZ_COMMON block from the
!CONFIG_FAIR_GROUP_SCHED definition of update_blocked_averages() by
using the newly-introduced update_blocked_load_status() helper.
No change in functionality intended.
[ Additions by Peter Zijlstra. ]
Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.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/20190603115424.7951-1-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Non-inline io_schedule() was introduced in:
commit 10ab56434f ("sched/core: Separate out io_schedule_prepare() and io_schedule_finish()")
Keep in line with io_schedule_timeout(), otherwise "/proc/<pid>/wchan" will
report io_schedule() rather than its callers when waiting for IO.
Reported-by: Jilong Kou <koujilong@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miao Xie <miaoxie@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 10ab56434f ("sched/core: Separate out io_schedule_prepare() and io_schedule_finish()")
Link: https://lkml.kernel.org/r/20190603091338.2695-1-gaoxiang25@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
perf_sample_regs_user() uses 'current->mm' to test for the presence of
userspace, but this is insufficient, consider use_mm().
A better test is: '!(current->flags & PF_KTHREAD)', exec() clears
PF_KTHREAD after it sets the new ->mm but before it drops to userspace
for the first time.
Possibly obsoletes: bf05fc25f2 ("powerpc/perf: Fix oops when kthread execs user process")
Reported-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Reported-by: Young Xiao <92siuyang@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4018994f3d ("perf: Add ability to attach user level registers dump to sample")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If the architecture supports the batching of jump label updates, use it!
An easy way to see the benefits of this patch is switching the
schedstats on and off. For instance:
-------------------------- %< ----------------------------
#!/bin/sh
while [ true ]; do
sysctl -w kernel.sched_schedstats=1
sleep 2
sysctl -w kernel.sched_schedstats=0
sleep 2
done
-------------------------- >% ----------------------------
while watching the IPI count:
-------------------------- %< ----------------------------
# watch -n1 "cat /proc/interrupts | grep Function"
-------------------------- >% ----------------------------
With the current mode, it is possible to see +- 168 IPIs each 2 seconds,
while with this patch the number of IPIs goes to 3 each 2 seconds.
Regarding the performance impact of this patch set, I made two measurements:
The time to update a key (the task that is causing the change)
The time to run the int3 handler (the side effect on a thread that
hits the code being changed)
The schedstats static key was chosen as the key to being switched on and off.
The reason being is that it is used in more than 56 places, in a hot path. The
change in the schedstats static key will be done with the following command:
while [ true ]; do
sysctl -w kernel.sched_schedstats=1
usleep 500000
sysctl -w kernel.sched_schedstats=0
usleep 500000
done
In this way, they key will be updated twice per second. To force the hit of the
int3 handler, the system will also run a kernel compilation with two jobs per
CPU. The test machine is a two nodes/24 CPUs box with an Intel Xeon processor
@2.27GHz.
Regarding the update part, on average, the regular kernel takes 57 ms to update
the schedstats key, while the kernel with the batch updates takes just 1.4 ms
on average. Although it seems to be too good to be true, it makes sense: the
schedstats key is used in 56 places, so it was expected that it would take
around 56 times to update the keys with the current implementation, as the
IPIs are the most expensive part of the update.
Regarding the int3 handler, the non-batch handler takes 45 ns on average, while
the batch version takes around 180 ns. At first glance, it seems to be a high
value. But it is not, considering that it is doing 56 updates, rather than one!
It is taking four times more, only. This gain is possible because the patch
uses a binary search in the vector: log2(56)=5.8. So, it was expected to have
an overhead within four times.
(voice of tv propaganda) But, that is not all! As the int3 handler keeps on for
a shorter period (because the update part is on for a shorter time), the number
of hits in the int3 handler decreased by 10%.
The question then is: Is it worth paying the price of "135 ns" more in the int3
handler?
Considering that, in this test case, we are saving the handling of 53 IPIs,
that takes more than these 135 ns, it seems to be a meager price to be paid.
Moreover, the test case was forcing the hit of the int3, in practice, it
does not take that often. While the IPI takes place on all CPUs, hitting
the int3 handler or not!
For instance, in an isolated CPU with a process running in user-space
(nohz_full use-case), the chances of hitting the int3 handler is barely zero,
while there is no way to avoid the IPIs. By bounding the IPIs, we are improving
a lot this scenario.
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/acc891dbc2dbc9fd616dd680529a2337b1d1274c.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In the batching mode, all the entries of a given key are updated at once.
During the update of a key, a hit in the int3 handler will check if the
hitting code address belongs to one of these keys.
To optimize the search of a given code in the vector of entries being
updated, a binary search is used. The binary search relies on the order
of the entries of a key by its code. Hence the keys need to be sorted
by the code too, so sort the entries of a given key by the code.
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/f57ae83e0592418ba269866bb7ade570fc8632e0.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move the check if a jump_entry is valid to a function. No functional
change.
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/56b69bd3f8e644ed64f2dbde7c088030b8cbe76b.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull timer fixes from Thomas Gleixner:
"A set of small fixes:
- Repair the ktime_get_coarse() functions so they actually deliver
what they are supposed to: tick granular time stamps. The current
code missed to add the accumulated nanoseconds part of the
timekeeper so the resulting granularity was 1 second.
- Prevent the tracer from infinitely recursing into time getter
functions in the arm architectured timer by marking these functions
notrace
- Fix a trivial compiler warning caused by wrong qualifier ordering"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timekeeping: Repair ktime_get_coarse*() granularity
clocksource/drivers/arm_arch_timer: Don't trace count reader functions
clocksource/drivers/timer-ti-dm: Change to new style declaration
Alexei Starovoitov says:
====================
pull-request: bpf 2019-06-15
The following pull-request contains BPF updates for your *net* tree.
The main changes are:
1) fix stack layout of JITed x64 bpf code, from Alexei.
2) fix out of bounds memory access in bpf_sk_storage, from Arthur.
3) fix lpm trie walk, from Jonathan.
4) fix nested bpf_perf_event_output, from Matt.
5) and several other fixes.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
BPF_PROG_TYPE_RAW_TRACEPOINTs can be executed nested on the same CPU, as
they do not increment bpf_prog_active while executing.
This enables three levels of nesting, to support
- a kprobe or raw tp or perf event,
- another one of the above that irq context happens to call, and
- another one in nmi context
(at most one of which may be a kprobe or perf event).
Fixes: 20b9d7ac48 ("bpf: avoid excessive stack usage for perf_sample_data")
Signed-off-by: Matt Mullins <mmullins@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Out of range read of stack trace output
- Fix for NULL pointer dereference in trace_uprobe_create()
- Fix to a livepatching / ftrace permission race in the module code
- Fix for NULL pointer dereference in free_ftrace_func_mapper()
- A couple of build warning clean ups
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Merge tag 'trace-v5.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
- Out of range read of stack trace output
- Fix for NULL pointer dereference in trace_uprobe_create()
- Fix to a livepatching / ftrace permission race in the module code
- Fix for NULL pointer dereference in free_ftrace_func_mapper()
- A couple of build warning clean ups
* tag 'trace-v5.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftrace: Fix NULL pointer dereference in free_ftrace_func_mapper()
module: Fix livepatch/ftrace module text permissions race
tracing/uprobe: Fix obsolete comment on trace_uprobe_create()
tracing/uprobe: Fix NULL pointer dereference in trace_uprobe_create()
tracing: Make two symbols static
tracing: avoid build warning with HAVE_NOP_MCOUNT
tracing: Fix out-of-range read in trace_stack_print()
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>
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>
Pull cgroup fixes from Tejun Heo:
"This has an unusually high density of tricky fixes:
- task_get_css() could deadlock when it races against a dying cgroup.
- cgroup.procs didn't list thread group leaders with live threads.
This could mislead readers to think that a cgroup is empty when
it's not. Fixed by making PROCS iterator include dead tasks. I made
a couple mistakes making this change and this pull request contains
a couple follow-up patches.
- When cpusets run out of online cpus, it updates cpusmasks of member
tasks in bizarre ways. Joel improved the behavior significantly"
* 'for-5.2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cpuset: restore sanity to cpuset_cpus_allowed_fallback()
cgroup: Fix css_task_iter_advance_css_set() cset skip condition
cgroup: css_task_iter_skip()'d iterators must be advanced before accessed
cgroup: Include dying leaders with live threads in PROCS iterations
cgroup: Implement css_task_iter_skip()
cgroup: Call cgroup_release() before __exit_signal()
docs cgroups: add another example size for hugetlb
cgroup: Use css_tryget() instead of css_tryget_online() in task_get_css()
Convert proc_dointvec_minmax_bpf_stats() into a more generic
helper, since we are going to use jump labels more often.
Note that sysctl_bpf_stats_enabled is removed, since
it is no longer needed/used.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
.ndo_xdp_xmit() assumes it is called under RCU. For example virtio_net
uses RCU to detect it has setup the resources for tx. The assumption
accidentally broke when introducing bulk queue in devmap.
Fixes: 5d053f9da4 ("bpf: devmap prepare xdp frames for bulking")
Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Toshiaki Makita <toshiaki.makita1@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
dev_map_free() waits for flush_needed bitmap to be empty in order to
ensure all flush operations have completed before freeing its entries.
However the corresponding clear_bit() was called before using the
entries, so the entries could be used after free.
All access to the entries needs to be done before clearing the bit.
It seems commit a5e2da6e97 ("bpf: netdev is never null in
__dev_map_flush") accidentally changed the clear_bit() and memory access
order.
Note that the problem happens only in __dev_map_flush(), not in
dev_map_flush_old(). dev_map_flush_old() is called only after nulling
out the corresponding netdev_map entry, so dev_map_free() never frees
the entry thus no such race happens there.
Fixes: a5e2da6e97 ("bpf: netdev is never null in __dev_map_flush")
Signed-off-by: Toshiaki Makita <toshiaki.makita1@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Convert the PM documents to ReST, in order to allow them to
build with Sphinx.
The conversion is actually:
- add blank lines and indentation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Commit 0597c49c69 ("tracing/uprobes: Use dyn_event framework for
uprobe events") cleaned up the usage of trace_uprobe_create(), and the
function has been no longer used for removing uprobe/uretprobe.
Link: http://lkml.kernel.org/r/20190614074026.8045-2-devel@etsukata.com
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Eiichi Tsukata <devel@etsukata.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Fix sparse warnings:
kernel/trace/trace.c:6927:24: warning:
symbol 'get_tracing_log_err' was not declared. Should it be static?
kernel/trace/trace.c:8196:15: warning:
symbol 'trace_instance_dir' was not declared. Should it be static?
Link: http://lkml.kernel.org/r/20190614153210.24424-1-yuehaibing@huawei.com
Acked-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Selecting HAVE_NOP_MCOUNT enables -mnop-mcount (if gcc supports it)
and sets CC_USING_NOP_MCOUNT. Reuse __is_defined (which is suitable for
testing CC_USING_* defines) to avoid conditional compilation and fix
the following gcc 9 warning on s390:
kernel/trace/ftrace.c:2514:1: warning: ‘ftrace_code_disable’ defined
but not used [-Wunused-function]
Link: http://lkml.kernel.org/r/patch.git-1a82d13f33ac.your-ad-here.call-01559732716-ext-6629@work.hours
Fixes: 2f4df0017b ("tracing: Add -mcount-nop option support")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
In order to prepare to add them to the Kernel API book,
convert the files to ReST format.
The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Convert the cgroup-v1 files to ReST format, in order to
allow a later addition to the admin-guide.
The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
The inline keyword was not at the beginning of the function declarations.
Fix the following warnings triggered when using W=1:
kernel/time/clocksource.c:108:1: warning: 'inline' is not at beginning of declaration [-Wold-style-declaration]
kernel/time/clocksource.c:113:1: warning: 'inline' is not at beginning of declaration [-Wold-style-declaration]
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: trivial@kernel.org
Cc: kernel-janitors@vger.kernel.org
Cc: John Stultz <john.stultz@linaro.org>
Cc: Stephen Boyd <sboyd@kernel.org>
Link: https://lkml.kernel.org/r/20190524103339.28787-1-malat@debian.org
Jason reported that the coarse ktime based time getters advance only once
per second and not once per tick as advertised.
The code reads only the monotonic base time, which advances once per
second. The nanoseconds are accumulated on every tick in xtime_nsec up to
a second and the regular time getters take this nanoseconds offset into
account, but the ktime_get_coarse*() implementation fails to do so.
Add the accumulated xtime_nsec value to the monotonic base time to get the
proper per tick advancing coarse tinme.
Fixes: b9ff604cff ("timekeeping: Add ktime_get_coarse_with_offset")
Reported-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: Sultan Alsawaf <sultan@kerneltoast.com>
Cc: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1906132136280.1791@nanos.tec.linutronix.de
The declaration for pfn_is_nosave is only available in
kernel/power/power.h. Since this function can be override in arch,
expose it globally. Having a prototype will make sure to avoid warning
(sometime treated as error with W=1) such as:
arch/powerpc/kernel/suspend.c:18:5: error: no previous prototype for 'pfn_is_nosave' [-Werror=missing-prototypes]
This moves the declaration into a globally visible header file and add
missing include to avoid a warning on powerpc.
Also remove the duplicated prototypes since not required anymore.
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
In module_add_modinfo_attrs if sysfs_create_file
fails, we forget to free allocated modinfo_attrs
and roll back the sysfs files.
Fixes: 03e88ae1b1 ("[PATCH] fix module sysfs files reference counting")
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Logan noticed that devm_memremap_pages_release() kills the percpu_ref
drops all the page references that were acquired at init and then
immediately proceeds to unplug, arch_remove_memory(), the backing pages
for the pagemap. If for some reason device shutdown actually collides
with a busy / elevated-ref-count page then arch_remove_memory() should
be deferred until after that reference is dropped.
As it stands the "wait for last page ref drop" happens *after*
devm_memremap_pages_release() returns, which is obviously too late and
can lead to crashes.
Fix this situation by assigning the responsibility to wait for the
percpu_ref to go idle to devm_memremap_pages() with a new ->cleanup()
callback. Implement the new cleanup callback for all
devm_memremap_pages() users: pmem, devdax, hmm, and p2pdma.
Link: http://lkml.kernel.org/r/155727339156.292046.5432007428235387859.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 41e94a8513 ("add devm_memremap_pages")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use the new devm_release_action() facility to allow
devm_memremap_pages_release() to be manually triggered.
Link: http://lkml.kernel.org/r/155727337088.292046.5774214552136776763.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The sync_exp_work_done() function uses smp_mb__before_atomic(), but
there is no obvious atomic in the ensuing code. The ordering is
absolutely required for grace periods to work correctly, so this
commit upgrades the smp_mb__before_atomic() to smp_mb().
Fixes: 6fba2b3767 ("rcu: Remove deprecated RCU debugfs tracing code")
Reported-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
In the case that a process is constrained by taskset(1) (i.e.
sched_setaffinity(2)) to a subset of available cpus, and all of those are
subsequently offlined, the scheduler will set tsk->cpus_allowed to
the current value of task_cs(tsk)->effective_cpus.
This is done via a call to do_set_cpus_allowed() in the context of
cpuset_cpus_allowed_fallback() made by the scheduler when this case is
detected. This is the only call made to cpuset_cpus_allowed_fallback()
in the latest mainline kernel.
However, this is not sane behavior.
I will demonstrate this on a system running the latest upstream kernel
with the following initial configuration:
# grep -i cpu /proc/$$/status
Cpus_allowed: ffffffff,fffffff
Cpus_allowed_list: 0-63
(Where cpus 32-63 are provided via smt.)
If we limit our current shell process to cpu2 only and then offline it
and reonline it:
# taskset -p 4 $$
pid 2272's current affinity mask: ffffffffffffffff
pid 2272's new affinity mask: 4
# echo off > /sys/devices/system/cpu/cpu2/online
# dmesg | tail -3
[ 2195.866089] process 2272 (bash) no longer affine to cpu2
[ 2195.872700] IRQ 114: no longer affine to CPU2
[ 2195.879128] smpboot: CPU 2 is now offline
# echo on > /sys/devices/system/cpu/cpu2/online
# dmesg | tail -1
[ 2617.043572] smpboot: Booting Node 0 Processor 2 APIC 0x4
We see that our current process now has an affinity mask containing
every cpu available on the system _except_ the one we originally
constrained it to:
# grep -i cpu /proc/$$/status
Cpus_allowed: ffffffff,fffffffb
Cpus_allowed_list: 0-1,3-63
This is not sane behavior, as the scheduler can now not only place the
process on previously forbidden cpus, it can't even schedule it on
the cpu it was originally constrained to!
Other cases result in even more exotic affinity masks. Take for instance
a process with an affinity mask containing only cpus provided by smt at
the moment that smt is toggled, in a configuration such as the following:
# taskset -p f000000000 $$
# grep -i cpu /proc/$$/status
Cpus_allowed: 000000f0,00000000
Cpus_allowed_list: 36-39
A double toggle of smt results in the following behavior:
# echo off > /sys/devices/system/cpu/smt/control
# echo on > /sys/devices/system/cpu/smt/control
# grep -i cpus /proc/$$/status
Cpus_allowed: ffffff00,ffffffff
Cpus_allowed_list: 0-31,40-63
This is even less sane than the previous case, as the new affinity mask
excludes all smt-provided cpus with ids less than those that were
previously in the affinity mask, as well as those that were actually in
the mask.
With this patch applied, both of these cases end in the following state:
# grep -i cpu /proc/$$/status
Cpus_allowed: ffffffff,ffffffff
Cpus_allowed_list: 0-63
The original policy is discarded. Though not ideal, it is the simplest way
to restore sanity to this fallback case without reinventing the cpuset
wheel that rolls down the kernel just fine in cgroup v2. A user who wishes
for the previous affinity mask to be restored in this fallback case can use
that mechanism instead.
This patch modifies scheduler behavior by instead resetting the mask to
task_cs(tsk)->cpus_allowed by default, and cpu_possible mask in legacy
mode. I tested the cases above on both modes.
Note that the scheduler uses this fallback mechanism if and only if
_every_ other valid avenue has been traveled, and it is the last resort
before calling BUG().
Suggested-by: Waiman Long <longman@redhat.com>
Suggested-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Joel Savitz <jsavitz@redhat.com>
Acked-by: Phil Auld <pauld@redhat.com>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Compiling kernel/bpf/core.c with W=1 causes a flood of warnings:
kernel/bpf/core.c:1198:65: warning: initialized field overwritten [-Woverride-init]
1198 | #define BPF_INSN_3_TBL(x, y, z) [BPF_##x | BPF_##y | BPF_##z] = true
| ^~~~
kernel/bpf/core.c:1087:2: note: in expansion of macro 'BPF_INSN_3_TBL'
1087 | INSN_3(ALU, ADD, X), \
| ^~~~~~
kernel/bpf/core.c:1202:3: note: in expansion of macro 'BPF_INSN_MAP'
1202 | BPF_INSN_MAP(BPF_INSN_2_TBL, BPF_INSN_3_TBL),
| ^~~~~~~~~~~~
kernel/bpf/core.c:1198:65: note: (near initialization for 'public_insntable[12]')
1198 | #define BPF_INSN_3_TBL(x, y, z) [BPF_##x | BPF_##y | BPF_##z] = true
| ^~~~
kernel/bpf/core.c:1087:2: note: in expansion of macro 'BPF_INSN_3_TBL'
1087 | INSN_3(ALU, ADD, X), \
| ^~~~~~
kernel/bpf/core.c:1202:3: note: in expansion of macro 'BPF_INSN_MAP'
1202 | BPF_INSN_MAP(BPF_INSN_2_TBL, BPF_INSN_3_TBL),
| ^~~~~~~~~~~~
98 copies of the above.
The attached patch silences the warnings, because we *know* we're overwriting
the default initializer. That leaves bpf/core.c with only 6 other warnings,
which become more visible in comparison.
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
When "deep" suspend is enabled, all CPUs except the primary CPU are frozen
via CPU hotplug one by one. After all secondary CPUs are unplugged the
wakeup pending condition is evaluated and if pending the suspend operation
is aborted and the secondary CPUs are brought up again.
CPU hotplug is a slow operation, so it makes sense to check for wakeup
pending in the freezer loop before bringing down the next CPU. This
improves the system suspend abort latency significantly.
[ tglx: Massaged changelog and improved printk message ]
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: iri Kosina <jkosina@suse.cz>
Cc: Mukesh Ojha <mojha@codeaurora.org>
Cc: linux-pm@vger.kernel.org
Link: https://lkml.kernel.org/r/1559536263-16472-1-git-send-email-pkondeti@codeaurora.org
The *affd argument is neither used in irq_build_affinity_masks() nor
__irq_build_affinity_masks(). Remove it.
Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Cc: Minwoo Im <minwoo.im@samsung.com>
Cc: linux-block@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602112117.31839-1-minwoo.im.dev@gmail.com
The circular buffers are now validated with selftests. The next interrupt
index algorithm which is the hardest part to validate needs extra coverage.
Add a selftest which uses the intervals stored in the arrays and insert all
the values except the last one. The next event computation must return the
same value as the last element which was not inserted.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20190527205521.12091-9-daniel.lezcano@linaro.org
Due to the complexity of the code and the difficulty to debug it, add some
selftests to the framework in order to spot issues or regression at boot
time when the runtime testing is enabled for this subsystem.
This tests the circular buffer at the limits and validates:
- the encoding / decoding of the values
- the macro to browse the irq timings circular buffer
- the function to push data in the circular buffer
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20190527205521.12091-7-daniel.lezcano@linaro.org
For the next patches providing the selftest, it is required to insert
interval values directly in the buffer in order to check the correctness of
the code. Encapsulate the code doing that in a always inline function in
order to reuse it in the test code.
No functional changes.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20190527205521.12091-6-daniel.lezcano@linaro.org
For the next patches providing the selftest, it is required to artificially
insert timings value in the circular buffer in order to check the
correctness of the code. Encapsulate the common code between the future
test code and the current code with an always-inline tag.
No functional change.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20190527205521.12091-5-daniel.lezcano@linaro.org
With a minimal period and if there is a period which is a multiple of it
but lesser than the max period then it will be detected before and the
minimal period will be never reached.
1 2 1 2 1 2 1 2 1 2 1 2
<-----> <-----> <----->
<-> <-> <-> <-> <-> <->
In that case, the minimum period is 2 and the maximum period is 5. That
means all repeating pattern of 2 will be detected as repeating pattern of
4, it is pointless to go up to 2 when searching for the period as it will
always fail.
Remove one loop iteration by increasing the minimal period to 3.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20190527205521.12091-4-daniel.lezcano@linaro.org
It appears the index beginning computation is not correct, the current
code does:
i = (irqts->count & IRQ_TIMINGS_MASK) - 1
If irqts->count is equal to zero, we end up with an index equal to -1,
but that does not happen because the function checks against zero
before and returns in such case.
However, if irqts->count is a multiple of IRQ_TIMINGS_SIZE, the
resulting & bit op will be zero and leads also to a -1 index.
Re-introduce the iteration loop belonging to the previous variance
code which was correct.
Fixes: bbba0e7c5c "genirq/timings: Add array suffix computation code"
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20190527205521.12091-3-daniel.lezcano@linaro.org
The current code is luckily working with most of the interval samples
testing but actually it fails to correctly detect pattern repetition
breaking at the end of the buffer.
Narrowing down the bug has been a real pain because of the pointers,
so the routine is rewrittne by using indexes instead.
Fixes: bbba0e7c5c "genirq/timings: Add array suffix computation code"
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20190527205521.12091-2-daniel.lezcano@linaro.org
Pull ptrace fixes from Eric Biederman:
"This is just two very minor fixes:
- prevent ptrace from reading unitialized kernel memory found twice
by syzkaller
- restore a missing smp_rmb in ptrace_may_access and add comment tp
it so it is not removed by accident again.
Apologies for being a little slow about getting this to you, I am
still figuring out how to develop with a little baby in the house"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
ptrace: restore smp_rmb() in __ptrace_may_access()
signal/ptrace: Don't leak unitialized kernel memory with PTRACE_PEEK_SIGINFO
Restore the read memory barrier in __ptrace_may_access() that was deleted
a couple years ago. Also add comments on this barrier and the one it pairs
with to explain why they're there (as far as I understand).
Fixes: bfedb58925 ("mm: Add a user_ns owner to mm_struct and fix ptrace permission checks")
Cc: stable@vger.kernel.org
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
With a specifically contrived memory layout where there is no physical
memory available to the kernel below the 4GB boundary, we will fail to
perform the initial swiotlb_init() call and set no_iotlb_memory to true.
There are drivers out there that call into swiotlb_nr_tbl() to determine
whether they can use the SWIOTLB. With the right DMA_BIT_MASK() value
for these drivers (say 64-bit), they won't ever need to hit
swiotlb_tbl_map_single() so this can go unoticed and we would be
possibly lying about those drivers.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Avoid repeating the zeroing of global swiotlb variables in two locations
and introduce swiotlb_cleanup() to do that.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Thomas Gleixner