This is just a cleanup addition to Jann's fix to properly update the
transaction ID for the slub slowpath in commit fd4d9c7d0c ("mm: slub:
add missing TID bump..").
The transaction ID is what protects us against any concurrent accesses,
but we should really also make sure to make the 'freelist' comparison
itself always use the same freelist value that we then used as the new
next free pointer.
Jann points out that if we do all of this carefully, we could skip the
transaction ID update for all the paths that only remove entries from
the lists, and only update the TID when adding entries (to avoid the ABA
issue with cmpxchg and list handling re-adding a previously seen value).
But this patch just does the "make sure to cmpxchg the same value we
used" rather than then try to be clever.
Acked-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When kmem_cache_alloc_bulk() attempts to allocate N objects from a percpu
freelist of length M, and N > M > 0, it will first remove the M elements
from the percpu freelist, then call ___slab_alloc() to allocate the next
element and repopulate the percpu freelist. ___slab_alloc() can re-enable
IRQs via allocate_slab(), so the TID must be bumped before ___slab_alloc()
to properly commit the freelist head change.
Fix it by unconditionally bumping c->tid when entering the slowpath.
Cc: stable@vger.kernel.org
Fixes: ebe909e0fd ("slub: improve bulk alloc strategy")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If we are already under list_lock, don't call kmalloc(). Otherwise we
will run into a deadlock because kmalloc() also tries to grab the same
lock.
Fix the problem by using a static bitmap instead.
WARNING: possible recursive locking detected
--------------------------------------------
mount-encrypted/4921 is trying to acquire lock:
(&(&n->list_lock)->rlock){-.-.}, at: ___slab_alloc+0x104/0x437
but task is already holding lock:
(&(&n->list_lock)->rlock){-.-.}, at: __kmem_cache_shutdown+0x81/0x3cb
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&(&n->list_lock)->rlock);
lock(&(&n->list_lock)->rlock);
*** DEADLOCK ***
Link: http://lkml.kernel.org/r/20191108193958.205102-2-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull scheduler updates from Ingo Molnar:
"These were the main changes in this cycle:
- More -rt motivated separation of CONFIG_PREEMPT and
CONFIG_PREEMPTION.
- Add more low level scheduling topology sanity checks and warnings
to filter out nonsensical topologies that break scheduling.
- Extend uclamp constraints to influence wakeup CPU placement
- Make the RT scheduler more aware of asymmetric topologies and CPU
capacities, via uclamp metrics, if CONFIG_UCLAMP_TASK=y
- Make idle CPU selection more consistent
- Various fixes, smaller cleanups, updates and enhancements - please
see the git log for details"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (58 commits)
sched/fair: Define sched_idle_cpu() only for SMP configurations
sched/topology: Assert non-NUMA topology masks don't (partially) overlap
idle: fix spelling mistake "iterrupts" -> "interrupts"
sched/fair: Remove redundant call to cpufreq_update_util()
sched/psi: create /proc/pressure and /proc/pressure/{io|memory|cpu} only when psi enabled
sched/fair: Fix sgc->{min,max}_capacity calculation for SD_OVERLAP
sched/fair: calculate delta runnable load only when it's needed
sched/cputime: move rq parameter in irqtime_account_process_tick
stop_machine: Make stop_cpus() static
sched/debug: Reset watchdog on all CPUs while processing sysrq-t
sched/core: Fix size of rq::uclamp initialization
sched/uclamp: Fix a bug in propagating uclamp value in new cgroups
sched/fair: Load balance aggressively for SCHED_IDLE CPUs
sched/fair : Improve update_sd_pick_busiest for spare capacity case
watchdog: Remove soft_lockup_hrtimer_cnt and related code
sched/rt: Make RT capacity-aware
sched/fair: Make EAS wakeup placement consider uclamp restrictions
sched/fair: Make task_fits_capacity() consider uclamp restrictions
sched/uclamp: Rename uclamp_util_with() into uclamp_rq_util_with()
sched/uclamp: Make uclamp util helpers use and return UL values
...
The allocation mask is no longer used by on_each_cpu_cond() and
on_each_cpu_cond_mask() and can be removed.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20200117090137.1205765-4-bigeasy@linutronix.de
Commit 96a2b03f28 ("mm, debug_pagelloc: use static keys to enable
debugging") has introduced a static key to reduce overhead when
debug_pagealloc is compiled in but not enabled. It relied on the
assumption that jump_label_init() is called before parse_early_param()
as in start_kernel(), so when the "debug_pagealloc=on" option is parsed,
it is safe to enable the static key.
However, it turns out multiple architectures call parse_early_param()
earlier from their setup_arch(). x86 also calls jump_label_init() even
earlier, so no issue was found while testing the commit, but same is not
true for e.g. ppc64 and s390 where the kernel would not boot with
debug_pagealloc=on as found by our QA.
To fix this without tricky changes to init code of multiple
architectures, this patch partially reverts the static key conversion
from 96a2b03f28. Init-time and non-fastpath calls (such as in arch
code) of debug_pagealloc_enabled() will again test a simple bool
variable. Fastpath mm code is converted to a new
debug_pagealloc_enabled_static() variant that relies on the static key,
which is enabled in a well-defined point in mm_init() where it's
guaranteed that jump_label_init() has been called, regardless of
architecture.
[sfr@canb.auug.org.au: export _debug_pagealloc_enabled_early]
Link: http://lkml.kernel.org/r/20200106164944.063ac07b@canb.auug.org.au
Link: http://lkml.kernel.org/r/20191219130612.23171-1-vbabka@suse.cz
Fixes: 96a2b03f28 ("mm, debug_pagelloc: use static keys to enable debugging")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Qian Cai <cai@lca.pw>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT.
Both PREEMPT and PREEMPT_RT require the same functionality which today
depends on CONFIG_PREEMPT.
Switch the pte_unmap_same() and SLUB code over to use CONFIG_PREEMPTION.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Chistoph Lameter <cl@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20191015191821.11479-26-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The function doesn't need to return any value, and the check can be done
in one pass.
There is a behavior change: before the patch, we stop at the first invalid
free object; after the patch, we stop at the first invalid object, free or
in use. This shouldn't matter because the original behavior isn't
intended anyway.
Link: http://lkml.kernel.org/r/20191108193958.205102-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 1b7e816fc8 ("mm: slub: Fix slab walking for init_on_free")
fixed one problem with the slab walking but missed a key detail: When
walking the list, the head and tail pointers need to be updated since we
end up reversing the list as a result. Without doing this, bulk free is
broken.
One way this is exposed is a NULL pointer with slub_debug=F:
=============================================================================
BUG skbuff_head_cache (Tainted: G T): Object already free
-----------------------------------------------------------------------------
INFO: Slab 0x000000000d2d2f8f objects=16 used=3 fp=0x0000000064309071 flags=0x3fff00000000201
BUG: kernel NULL pointer dereference, address: 0000000000000000
Oops: 0000 [#1] PREEMPT SMP PTI
RIP: 0010:print_trailer+0x70/0x1d5
Call Trace:
<IRQ>
free_debug_processing.cold.37+0xc9/0x149
__slab_free+0x22a/0x3d0
kmem_cache_free_bulk+0x415/0x420
__kfree_skb_flush+0x30/0x40
net_rx_action+0x2dd/0x480
__do_softirq+0xf0/0x246
irq_exit+0x93/0xb0
do_IRQ+0xa0/0x110
common_interrupt+0xf/0xf
</IRQ>
Given we're now almost identical to the existing debugging code which
correctly walks the list, combine with that.
Link: https://lkml.kernel.org/r/20191104170303.GA50361@gandi.net
Link: http://lkml.kernel.org/r/20191106222208.26815-1-labbott@redhat.com
Fixes: 1b7e816fc8 ("mm: slub: Fix slab walking for init_on_free")
Signed-off-by: Laura Abbott <labbott@redhat.com>
Reported-by: Thibaut Sautereau <thibaut.sautereau@clip-os.org>
Acked-by: David Rientjes <rientjes@google.com>
Tested-by: Alexander Potapenko <glider@google.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <clipos@ssi.gouv.fr>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
slab_alloc_node() already zeroed out the freelist pointer if
init_on_free was on. Thibaut Sautereau noticed that the same needs to
be done for kmem_cache_alloc_bulk(), which performs the allocations
separately.
kmem_cache_alloc_bulk() is currently used in two places in the kernel,
so this change is unlikely to have a major performance impact.
SLAB doesn't require a similar change, as auto-initialization makes the
allocator store the freelist pointers off-slab.
Link: http://lkml.kernel.org/r/20191007091605.30530-1-glider@google.com
Fixes: 6471384af2 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options")
Signed-off-by: Alexander Potapenko <glider@google.com>
Reported-by: Thibaut Sautereau <thibaut@sautereau.fr>
Reported-by: Kees Cook <keescook@chromium.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Laura Abbott <labbott@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A long time ago we fixed a similar deadlock in show_slab_objects() [1].
However, it is apparently due to the commits like 01fb58bcba ("slab:
remove synchronous synchronize_sched() from memcg cache deactivation
path") and 03afc0e25f ("slab: get_online_mems for
kmem_cache_{create,destroy,shrink}"), this kind of deadlock is back by
just reading files in /sys/kernel/slab which will generate a lockdep
splat below.
Since the "mem_hotplug_lock" here is only to obtain a stable online node
mask while racing with NUMA node hotplug, in the worst case, the results
may me miscalculated while doing NUMA node hotplug, but they shall be
corrected by later reads of the same files.
WARNING: possible circular locking dependency detected
------------------------------------------------------
cat/5224 is trying to acquire lock:
ffff900012ac3120 (mem_hotplug_lock.rw_sem){++++}, at:
show_slab_objects+0x94/0x3a8
but task is already holding lock:
b8ff009693eee398 (kn->count#45){++++}, at: kernfs_seq_start+0x44/0xf0
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (kn->count#45){++++}:
lock_acquire+0x31c/0x360
__kernfs_remove+0x290/0x490
kernfs_remove+0x30/0x44
sysfs_remove_dir+0x70/0x88
kobject_del+0x50/0xb0
sysfs_slab_unlink+0x2c/0x38
shutdown_cache+0xa0/0xf0
kmemcg_cache_shutdown_fn+0x1c/0x34
kmemcg_workfn+0x44/0x64
process_one_work+0x4f4/0x950
worker_thread+0x390/0x4bc
kthread+0x1cc/0x1e8
ret_from_fork+0x10/0x18
-> #1 (slab_mutex){+.+.}:
lock_acquire+0x31c/0x360
__mutex_lock_common+0x16c/0xf78
mutex_lock_nested+0x40/0x50
memcg_create_kmem_cache+0x38/0x16c
memcg_kmem_cache_create_func+0x3c/0x70
process_one_work+0x4f4/0x950
worker_thread+0x390/0x4bc
kthread+0x1cc/0x1e8
ret_from_fork+0x10/0x18
-> #0 (mem_hotplug_lock.rw_sem){++++}:
validate_chain+0xd10/0x2bcc
__lock_acquire+0x7f4/0xb8c
lock_acquire+0x31c/0x360
get_online_mems+0x54/0x150
show_slab_objects+0x94/0x3a8
total_objects_show+0x28/0x34
slab_attr_show+0x38/0x54
sysfs_kf_seq_show+0x198/0x2d4
kernfs_seq_show+0xa4/0xcc
seq_read+0x30c/0x8a8
kernfs_fop_read+0xa8/0x314
__vfs_read+0x88/0x20c
vfs_read+0xd8/0x10c
ksys_read+0xb0/0x120
__arm64_sys_read+0x54/0x88
el0_svc_handler+0x170/0x240
el0_svc+0x8/0xc
other info that might help us debug this:
Chain exists of:
mem_hotplug_lock.rw_sem --> slab_mutex --> kn->count#45
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(kn->count#45);
lock(slab_mutex);
lock(kn->count#45);
lock(mem_hotplug_lock.rw_sem);
*** DEADLOCK ***
3 locks held by cat/5224:
#0: 9eff00095b14b2a0 (&p->lock){+.+.}, at: seq_read+0x4c/0x8a8
#1: 0eff008997041480 (&of->mutex){+.+.}, at: kernfs_seq_start+0x34/0xf0
#2: b8ff009693eee398 (kn->count#45){++++}, at:
kernfs_seq_start+0x44/0xf0
stack backtrace:
Call trace:
dump_backtrace+0x0/0x248
show_stack+0x20/0x2c
dump_stack+0xd0/0x140
print_circular_bug+0x368/0x380
check_noncircular+0x248/0x250
validate_chain+0xd10/0x2bcc
__lock_acquire+0x7f4/0xb8c
lock_acquire+0x31c/0x360
get_online_mems+0x54/0x150
show_slab_objects+0x94/0x3a8
total_objects_show+0x28/0x34
slab_attr_show+0x38/0x54
sysfs_kf_seq_show+0x198/0x2d4
kernfs_seq_show+0xa4/0xcc
seq_read+0x30c/0x8a8
kernfs_fop_read+0xa8/0x314
__vfs_read+0x88/0x20c
vfs_read+0xd8/0x10c
ksys_read+0xb0/0x120
__arm64_sys_read+0x54/0x88
el0_svc_handler+0x170/0x240
el0_svc+0x8/0xc
I think it is important to mention that this doesn't expose the
show_slab_objects to use-after-free. There is only a single path that
might really race here and that is the slab hotplug notifier callback
__kmem_cache_shrink (via slab_mem_going_offline_callback) but that path
doesn't really destroy kmem_cache_node data structures.
[1] http://lkml.iu.edu/hypermail/linux/kernel/1101.0/02850.html
[akpm@linux-foundation.org: add comment explaining why we don't need mem_hotplug_lock]
Link: http://lkml.kernel.org/r/1570192309-10132-1-git-send-email-cai@lca.pw
Fixes: 01fb58bcba ("slab: remove synchronous synchronize_sched() from memcg cache deactivation path")
Fixes: 03afc0e25f ("slab: get_online_mems for kmem_cache_{create,destroy,shrink}")
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "guarantee natural alignment for kmalloc()", v2.
This patch (of 2):
SLOB currently doesn't account its pages at all, so in /proc/meminfo the
Slab field shows zero. Modifying a counter on page allocation and
freeing should be acceptable even for the small system scenarios SLOB is
intended for. Since reclaimable caches are not separated in SLOB,
account everything as unreclaimable.
SLUB currently doesn't account kmalloc() and kmalloc_node() allocations
larger than order-1 page, that are passed directly to the page
allocator. As they also don't appear in /proc/slabinfo, it might look
like a memory leak. For consistency, account them as well. (SLAB
doesn't actually use page allocator directly, so no change there).
Ideally SLOB and SLUB would be handled in separate patches, but due to
the shared kmalloc_order() function and different kfree()
implementations, it's easier to patch both at once to prevent
inconsistencies.
Link: http://lkml.kernel.org/r/20190826111627.7505-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Darrick J . Wong" <darrick.wong@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Make working with compound pages easier", v2.
These three patches add three helpers and convert the appropriate
places to use them.
This patch (of 3):
It's unnecessarily hard to find out the size of a potentially huge page.
Replace 'PAGE_SIZE << compound_order(page)' with page_size(page).
Link: http://lkml.kernel.org/r/20190721104612.19120-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
tid_to_cpu() and tid_to_event() are only used in note_cmpxchg_failure()
when SLUB_DEBUG_CMPXCHG=y, so when SLUB_DEBUG_CMPXCHG=n by default, Clang
will complain that those unused functions.
Link: http://lkml.kernel.org/r/1568752232-5094-1-git-send-email-cai@lca.pw
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, a value of '1" is written to /sys/kernel/slab/<slab>/shrink
file to shrink the slab by flushing out all the per-cpu slabs and free
slabs in partial lists. This can be useful to squeeze out a bit more
memory under extreme condition as well as making the active object counts
in /proc/slabinfo more accurate.
This usually applies only to the root caches, as the SLUB_MEMCG_SYSFS_ON
option is usually not enabled and "slub_memcg_sysfs=1" not set. Even if
memcg sysfs is turned on, it is too cumbersome and impractical to manage
all those per-memcg sysfs files in a real production system.
So there is no practical way to shrink memcg caches. Fix this by enabling
a proper write to the shrink sysfs file of the root cache to scan all the
available memcg caches and shrink them as well. For a non-root memcg
cache (when SLUB_MEMCG_SYSFS_ON or slub_memcg_sysfs is on), only that
cache will be shrunk when written.
On a 2-socket 64-core 256-thread arm64 system with 64k page after
a parallel kernel build, the the amount of memory occupied by slabs
before shrinking slabs were:
# grep task_struct /proc/slabinfo
task_struct 53137 53192 4288 61 4 : tunables 0 0
0 : slabdata 872 872 0
# grep "^S[lRU]" /proc/meminfo
Slab: 3936832 kB
SReclaimable: 399104 kB
SUnreclaim: 3537728 kB
After shrinking slabs (by echoing "1" to all shrink files):
# grep "^S[lRU]" /proc/meminfo
Slab: 1356288 kB
SReclaimable: 263296 kB
SUnreclaim: 1092992 kB
# grep task_struct /proc/slabinfo
task_struct 2764 6832 4288 61 4 : tunables 0 0
0 : slabdata 112 112 0
Link: http://lkml.kernel.org/r/20190723151445.7385-1-longman@redhat.com
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To properly clear the slab on free with slab_want_init_on_free, we walk
the list of free objects using get_freepointer/set_freepointer.
The value we get from get_freepointer may not be valid. This isn't an
issue since an actual value will get written later but this means
there's a chance of triggering a bug if we use this value with
set_freepointer:
kernel BUG at mm/slub.c:306!
invalid opcode: 0000 [#1] PREEMPT PTI
CPU: 0 PID: 0 Comm: swapper Not tainted 5.2.0-05754-g6471384a #4
RIP: 0010:kfree+0x58a/0x5c0
Code: 48 83 05 78 37 51 02 01 0f 0b 48 83 05 7e 37 51 02 01 48 83 05 7e 37 51 02 01 48 83 05 7e 37 51 02 01 48 83 05 d6 37 51 02 01 <0f> 0b 48 83 05 d4 37 51 02 01 48 83 05 d4 37 51 02 01 48 83 05 d4
RSP: 0000:ffffffff82603d90 EFLAGS: 00010002
RAX: ffff8c3976c04320 RBX: ffff8c3976c04300 RCX: 0000000000000000
RDX: ffff8c3976c04300 RSI: 0000000000000000 RDI: ffff8c3976c04320
RBP: ffffffff82603db8 R08: 0000000000000000 R09: 0000000000000000
R10: ffff8c3976c04320 R11: ffffffff8289e1e0 R12: ffffd52cc8db0100
R13: ffff8c3976c01a00 R14: ffffffff810f10d4 R15: ffff8c3976c04300
FS: 0000000000000000(0000) GS:ffffffff8266b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff8c397ffff000 CR3: 0000000125020000 CR4: 00000000000406b0
Call Trace:
apply_wqattrs_prepare+0x154/0x280
apply_workqueue_attrs_locked+0x4e/0xe0
apply_workqueue_attrs+0x36/0x60
alloc_workqueue+0x25a/0x6d0
workqueue_init_early+0x246/0x348
start_kernel+0x3c7/0x7ec
x86_64_start_reservations+0x40/0x49
x86_64_start_kernel+0xda/0xe4
secondary_startup_64+0xb6/0xc0
Modules linked in:
---[ end trace f67eb9af4d8d492b ]---
Fix this by ensuring the value we set with set_freepointer is either NULL
or another value in the chain.
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Fixes: 6471384af2 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options")
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "add init_on_alloc/init_on_free boot options", v10.
Provide init_on_alloc and init_on_free boot options.
These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.
Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes. SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.
Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.
As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations. There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.
This patch (of 2):
The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.
This is expected to be on-by-default on Android and Chrome OS. And it
gives the opportunity for anyone else to use it under distros too via the
boot args. (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)
init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes. Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.
init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion. This helps to ensure sensitive data
doesn't leak via use-after-free accesses.
Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory. The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag. Those are never
zero-initialized to preserve their semantics.
Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.
If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.
Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:
hackbench, init_on_free=1: +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)
Linux build with -j12, init_on_free=1: +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1: +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)
The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.
The new features are also going to pave the way for hardware memory
tagging (e.g. arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects. With MTE, tagging will have the
same cost as memory initialization.
Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized. There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.
[glider@google.com: v8]
Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz> [page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently the page accounting code is duplicated in SLAB and SLUB
internals. Let's move it into new (un)charge_slab_page helpers in the
slab_common.c file. These helpers will be responsible for statistics
(global and memcg-aware) and memcg charging. So they are replacing direct
memcg_(un)charge_slab() calls.
Link: http://lkml.kernel.org/r/20190611231813.3148843-6-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently SLUB uses a work scheduled after an RCU grace period to
deactivate a non-root kmem_cache. This mechanism can be reused for
kmem_caches release, but requires generalization for SLAB case.
Introduce kmemcg_cache_deactivate() function, which calls
allocator-specific __kmem_cache_deactivate() and schedules execution of
__kmem_cache_deactivate_after_rcu() with all necessary locks in a worker
context after an rcu grace period.
Here is the new calling scheme:
kmemcg_cache_deactivate()
__kmemcg_cache_deactivate() SLAB/SLUB-specific
kmemcg_rcufn() rcu
kmemcg_workfn() work
__kmemcg_cache_deactivate_after_rcu() SLAB/SLUB-specific
instead of:
__kmemcg_cache_deactivate() SLAB/SLUB-specific
slab_deactivate_memcg_cache_rcu_sched() SLUB-only
kmemcg_rcufn() rcu
kmemcg_workfn() work
kmemcg_cache_deact_after_rcu() SLUB-only
For consistency, all allocator-specific functions start with "__".
Link: http://lkml.kernel.org/r/20190611231813.3148843-4-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: reparent slab memory on cgroup removal", v7.
# Why do we need this?
We've noticed that the number of dying cgroups is steadily growing on most
of our hosts in production. The following investigation revealed an issue
in the userspace memory reclaim code [1], accounting of kernel stacks [2],
and also the main reason: slab objects.
The underlying problem is quite simple: any page charged to a cgroup holds
a reference to it, so the cgroup can't be reclaimed unless all charged
pages are gone. If a slab object is actively used by other cgroups, it
won't be reclaimed, and will prevent the origin cgroup from being
reclaimed.
Slab objects, and first of all vfs cache, is shared between cgroups, which
are using the same underlying fs, and what's even more important, it's
shared between multiple generations of the same workload. So if something
is running periodically every time in a new cgroup (like how systemd
works), we do accumulate multiple dying cgroups.
Strictly speaking pagecache isn't different here, but there is a key
difference: we disable protection and apply some extra pressure on LRUs of
dying cgroups, and these LRUs contain all charged pages. My experiments
show that with the disabled kernel memory accounting the number of dying
cgroups stabilizes at a relatively small number (~100, depends on memory
pressure and cgroup creation rate), and with kernel memory accounting it
grows pretty steadily up to several thousands.
Memory cgroups are quite complex and big objects (mostly due to percpu
stats), so it leads to noticeable memory losses. Memory occupied by dying
cgroups is measured in hundreds of megabytes. I've even seen a host with
more than 100Gb of memory wasted for dying cgroups. It leads to a
degradation of performance with the uptime, and generally limits the usage
of cgroups.
My previous attempt [3] to fix the problem by applying extra pressure on
slab shrinker lists caused a regressions with xfs and ext4, and has been
reverted [4]. The following attempts to find the right balance [5, 6]
were not successful.
So instead of trying to find a maybe non-existing balance, let's do
reparent accounted slab caches to the parent cgroup on cgroup removal.
# Implementation approach
There is however a significant problem with reparenting of slab memory:
there is no list of charged pages. Some of them are in shrinker lists,
but not all. Introducing of a new list is really not an option.
But fortunately there is a way forward: every slab page has a stable
pointer to the corresponding kmem_cache. So the idea is to reparent
kmem_caches instead of slab pages.
It's actually simpler and cheaper, but requires some underlying changes:
1) Make kmem_caches to hold a single reference to the memory cgroup,
instead of a separate reference per every slab page.
2) Stop setting page->mem_cgroup pointer for memcg slab pages and use
page->kmem_cache->memcg indirection instead. It's used only on
slab page release, so performance overhead shouldn't be a big issue.
3) Introduce a refcounter for non-root slab caches. It's required to
be able to destroy kmem_caches when they become empty and release
the associated memory cgroup.
There is a bonus: currently we release all memcg kmem_caches all together
with the memory cgroup itself. This patchset allows individual
kmem_caches to be released as soon as they become inactive and free.
Some additional implementation details are provided in corresponding
commit messages.
# Results
Below is the average number of dying cgroups on two groups of our
production hosts. They do run some sort of web frontend workload, the
memory pressure is moderate. As we can see, with the kernel memory
reparenting the number stabilizes in 60s range; however with the original
version it grows almost linearly and doesn't show any signs of plateauing.
The difference in slab and percpu usage between patched and unpatched
versions also grows linearly. In 7 days it exceeded 200Mb.
day 0 1 2 3 4 5 6 7
original 56 362 628 752 1070 1250 1490 1560
patched 23 46 51 55 60 57 67 69
mem diff(Mb) 22 74 123 152 164 182 214 241
# Links
[1]: commit 68600f623d ("mm: don't miss the last page because of round-off error")
[2]: commit 9b6f7e163c ("mm: rework memcg kernel stack accounting")
[3]: commit 172b06c32b ("mm: slowly shrink slabs with a relatively small number of objects")
[4]: commit a9a238e83f ("Revert "mm: slowly shrink slabs with a relatively small number of objects")
[5]: https://lkml.org/lkml/2019/1/28/1865
[6]: https://marc.info/?l=linux-mm&m=155064763626437&w=2
This patch (of 10):
Initialize kmem_cache->memcg_params.memcg pointer in memcg_link_cache()
rather than in init_memcg_params().
Once kmem_cache will hold a reference to the memory cgroup, it will
simplify the refcounting.
For non-root kmem_caches memcg_link_cache() is always called before the
kmem_cache becomes visible to a user, so it's safe.
Link: http://lkml.kernel.org/r/20190611231813.3148843-2-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This refactors common code of ksize() between the various allocators into
slab_common.c: __ksize() is the allocator-specific implementation without
instrumentation, whereas ksize() includes the required KASAN logic.
Link: http://lkml.kernel.org/r/20190626142014.141844-5-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently for CONFIG_SLUB, if a memcg kmem cache creation is failed and
the corresponding root kmem cache has SLAB_PANIC flag, the kernel will
be crashed. This is unnecessary as the kernel can handle the creation
failures of memcg kmem caches. Additionally CONFIG_SLAB does not
implement this behavior. So, to keep the behavior consistent between
SLAB and SLUB, removing the panic for memcg kmem cache creation
failures. The root kmem cache creation failure for SLAB_PANIC correctly
panics for both SLAB and SLUB.
Link: http://lkml.kernel.org/r/20190619232514.58994-1-shakeelb@google.com
Reported-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If ',' is not found, kmem_cache_flags() calls strlen() to find the end of
line. We can do it in a single pass using strchrnul().
Link: http://lkml.kernel.org/r/20190501053111.7950-1-ynorov@marvell.com
Signed-off-by: Yury Norov <ynorov@marvell.com>
Acked-by: Aaron Tomlin <atomlin@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now frozen slab can only be on the per cpu partial list.
Link: http://lkml.kernel.org/r/1554022325-11305-1-git-send-email-liu.xiang6@zte.com.cn
Signed-off-by: Liu Xiang <liu.xiang6@zte.com.cn>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When CONFIG_SLUB_DEBUG is not enabled, remove_full() is empty.
While CONFIG_SLUB_DEBUG is enabled, remove_full() can check
s->flags by itself. So kmem_cache_debug() is useless and
can be removed.
Link: http://lkml.kernel.org/r/1552577313-2830-1-git-send-email-liu.xiang6@zte.com.cn
Signed-off-by: Liu Xiang <liu.xiang6@zte.com.cn>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently we use the page->lru list for maintaining lists of slabs. We
have a list in the page structure (slab_list) that can be used for this
purpose. Doing so makes the code cleaner since we are not overloading the
lru list.
Use the slab_list instead of the lru list for maintaining lists of slabs.
Link: http://lkml.kernel.org/r/20190402230545.2929-6-tobin@kernel.org
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SLUB allocator makes heavy use of ifdef/endif pre-processor macros. The
pairing of these statements is at times hard to follow e.g. if the pair
are further than a screen apart or if there are nested pairs. We can
reduce cognitive load by adding a comment to the endif statement of form
#ifdef CONFIG_FOO
...
#endif /* CONFIG_FOO */
Add comments to endif pre-processor macros if ifdef/endif pair is not
immediately apparent.
Link: http://lkml.kernel.org/r/20190402230545.2929-5-tobin@kernel.org
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No architecture terminates the stack trace with ULONG_MAX anymore. Remove
the cruft.
While at it remove the pointless loop of clearing the stack array
completely. It's sufficient to clear the last entry as the consumers break
out on the first zeroed entry anyway.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Link: https://lkml.kernel.org/r/20190410103644.574058244@linutronix.de
Patch series "iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables",
v6.
This is a followup to the discussion in [1], [2].
IOMMUs using ARMv7 short-descriptor format require page tables (level 1
and 2) to be allocated within the first 4GB of RAM, even on 64-bit
systems.
For L1 tables that are bigger than a page, we can just use
__get_free_pages with GFP_DMA32 (on arm64 systems only, arm would still
use GFP_DMA).
For L2 tables that only take 1KB, it would be a waste to allocate a full
page, so we considered 3 approaches:
1. This series, adding support for GFP_DMA32 slab caches.
2. genalloc, which requires pre-allocating the maximum number of L2 page
tables (4096, so 4MB of memory).
3. page_frag, which is not very memory-efficient as it is unable to reuse
freed fragments until the whole page is freed. [3]
This series is the most memory-efficient approach.
stable@ note:
We confirmed that this is a regression, and IOMMU errors happen on 4.19
and linux-next/master on MT8173 (elm, Acer Chromebook R13). The issue
most likely starts from commit ad67f5a654 ("arm64: replace ZONE_DMA
with ZONE_DMA32"), i.e. 4.15, and presumably breaks a number of Mediatek
platforms (and maybe others?).
[1] https://lists.linuxfoundation.org/pipermail/iommu/2018-November/030876.html
[2] https://lists.linuxfoundation.org/pipermail/iommu/2018-December/031696.html
[3] https://patchwork.codeaurora.org/patch/671639/
This patch (of 3):
IOMMUs using ARMv7 short-descriptor format require page tables to be
allocated within the first 4GB of RAM, even on 64-bit systems. On arm64,
this is done by passing GFP_DMA32 flag to memory allocation functions.
For IOMMU L2 tables that only take 1KB, it would be a waste to allocate
a full page using get_free_pages, so we considered 3 approaches:
1. This patch, adding support for GFP_DMA32 slab caches.
2. genalloc, which requires pre-allocating the maximum number of L2
page tables (4096, so 4MB of memory).
3. page_frag, which is not very memory-efficient as it is unable
to reuse freed fragments until the whole page is freed.
This change makes it possible to create a custom cache in DMA32 zone using
kmem_cache_create, then allocate memory using kmem_cache_alloc.
We do not create a DMA32 kmalloc cache array, as there are currently no
users of kmalloc(..., GFP_DMA32). These calls will continue to trigger a
warning, as we keep GFP_DMA32 in GFP_SLAB_BUG_MASK.
This implies that calls to kmem_cache_*alloc on a SLAB_CACHE_DMA32
kmem_cache must _not_ use GFP_DMA32 (it is anyway redundant and
unnecessary).
Link: http://lkml.kernel.org/r/20181210011504.122604-2-drinkcat@chromium.org
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Sasha Levin <Alexander.Levin@microsoft.com>
Cc: Huaisheng Ye <yehs1@lenovo.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Yong Wu <yong.wu@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Tomasz Figa <tfiga@google.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No functional change.
Link: http://lkml.kernel.org/r/20190118235123.27843-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are two cases when put_cpu_partial() is invoked.
* __slab_free
* get_partial_node
This patch just makes it cover these two cases.
Link: http://lkml.kernel.org/r/20181025094437.18951-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
"addr" function argument is not used in alloc_consistency_checks() at
all, so remove it.
Link: http://lkml.kernel.org/r/20190211123214.35592-1-cai@lca.pw
Fixes: becfda68ab ("slub: convert SLAB_DEBUG_FREE to SLAB_CONSISTENCY_CHECKS")
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
new_slab_objects() will return immediately if freelist is not NULL.
if (freelist)
return freelist;
One more assignment operation could be avoided.
Link: http://lkml.kernel.org/r/20181229062512.30469-1-rocking@whu.edu.cn
Signed-off-by: Peng Wang <rocking@whu.edu.cn>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged. Normally,
this doesn't cause any issues, as both set_freepointer() and
get_freepointer() are called with a pointer with the same tag. However,
there are some issues with CONFIG_SLUB_DEBUG code. For example, when
__free_slub() iterates over objects in a cache, it passes untagged
pointers to check_object(). check_object() in turns calls
get_freepointer() with an untagged pointer, which causes the freepointer
to be restored incorrectly.
Add kasan_reset_tag to freelist_ptr(). Also add a detailed comment.
Link: http://lkml.kernel.org/r/bf858f26ef32eb7bd24c665755b3aee4bc58d0e4.1550103861.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reported-by: Qian Cai <cai@lca.pw>
Tested-by: Qian Cai <cai@lca.pw>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CONFIG_SLAB_FREELIST_HARDENED hashes freelist pointer with the address of
the object where the pointer gets stored. With tag based KASAN we don't
account for that when building freelist, as we call set_freepointer() with
the first argument untagged. This patch changes the code to properly
propagate tags throughout the loop.
Link: http://lkml.kernel.org/r/3df171559c52201376f246bf7ce3184fe21c1dc7.1549921721.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reported-by: Qian Cai <cai@lca.pw>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Evgeniy Stepanov <eugenis@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With tag based KASAN page_address() looks at the page flags to see whether
the resulting pointer needs to have a tag set. Since we don't want to set
a tag when page_address() is called on SLAB pages, we call
page_kasan_tag_reset() in kasan_poison_slab(). However in allocate_slab()
page_address() is called before kasan_poison_slab(). Fix it by changing
the order.
[andreyknvl@google.com: fix compilation error when CONFIG_SLUB_DEBUG=n]
Link: http://lkml.kernel.org/r/ac27cc0bbaeb414ed77bcd6671a877cf3546d56e.1550066133.git.andreyknvl@google.com
Link: http://lkml.kernel.org/r/cd895d627465a3f1c712647072d17f10883be2a1.1549921721.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgeniy Stepanov <eugenis@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kmemleak keeps two global variables, min_addr and max_addr, which store
the range of valid (encountered by kmemleak) pointer values, which it
later uses to speed up pointer lookup when scanning blocks.
With tagged pointers this range will get bigger than it needs to be. This
patch makes kmemleak untag pointers before saving them to min_addr and
max_addr and when performing a lookup.
Link: http://lkml.kernel.org/r/16e887d442986ab87fe87a755815ad92fa431a5f.1550066133.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Qian Cai <cai@lca.pw>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgeniy Stepanov <eugenis@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Right now we call kmemleak hooks before assigning tags to pointers in
KASAN hooks. As a result, when an objects gets allocated, kmemleak sees a
differently tagged pointer, compared to the one it sees when the object
gets freed. Fix it by calling KASAN hooks before kmemleak's ones.
Link: http://lkml.kernel.org/r/cd825aa4897b0fc37d3316838993881daccbe9f5.1549921721.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reported-by: Qian Cai <cai@lca.pw>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgeniy Stepanov <eugenis@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With CONFIG_HARDENED_USERCOPY enabled __check_heap_object() compares and
then subtracts a potentially tagged pointer with a non-tagged address of
the page that this pointer belongs to, which leads to unexpected
behavior.
Untag the pointer in __check_heap_object() before doing any of these
operations.
Link: http://lkml.kernel.org/r/7e756a298d514c4482f52aea6151db34818d395d.1546540962.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If __cmpxchg_double_slab() fails and (l != m), current code records
transition states of slub action.
Update the action after __cmpxchg_double_slab() success to record the
final state.
[akpm@linux-foundation.org: more whitespace cleanup]
Link: http://lkml.kernel.org/r/20181107013119.3816-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
node_match() is a static function and is only invoked in slub.c.
In all three places, `page' is ensured to be valid.
Link: http://lkml.kernel.org/r/20181106150245.1668-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cpu_slab is a per cpu variable which is allocated in all or none. If a
cpu_slab failed to be allocated, the slub is not usable.
We could use cpu_slab without validation in __flush_cpu_slab().
Link: http://lkml.kernel.org/r/20181103141218.22844-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
An object constructor can initialize pointers within this objects based on
the address of the object. Since the object address might be tagged, we
need to assign a tag before calling constructor.
The implemented approach is to assign tags to objects with constructors
when a slab is allocated and call constructors once as usual. The
downside is that such object would always have the same tag when it is
reallocated, so we won't catch use-after-frees on it.
Also pressign tags for objects from SLAB_TYPESAFE_BY_RCU caches, since
they can be validy accessed after having been freed.
Link: http://lkml.kernel.org/r/f158a8a74a031d66f0a9398a5b0ed453c37ba09a.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit splits the current CONFIG_KASAN config option into two:
1. CONFIG_KASAN_GENERIC, that enables the generic KASAN mode (the one
that exists now);
2. CONFIG_KASAN_SW_TAGS, that enables the software tag-based KASAN mode.
The name CONFIG_KASAN_SW_TAGS is chosen as in the future we will have
another hardware tag-based KASAN mode, that will rely on hardware memory
tagging support in arm64.
With CONFIG_KASAN_SW_TAGS enabled, compiler options are changed to
instrument kernel files with -fsantize=kernel-hwaddress (except the ones
for which KASAN_SANITIZE := n is set).
Both CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGS support both
CONFIG_KASAN_INLINE and CONFIG_KASAN_OUTLINE instrumentation modes.
This commit also adds empty placeholder (for now) implementation of
tag-based KASAN specific hooks inserted by the compiler and adjusts
common hooks implementation.
While this commit adds the CONFIG_KASAN_SW_TAGS config option, this option
is not selectable, as it depends on HAVE_ARCH_KASAN_SW_TAGS, which we will
enable once all the infrastracture code has been added.
Link: http://lkml.kernel.org/r/b2550106eb8a68b10fefbabce820910b115aa853.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The previous patch updated KASAN hooks signatures and their usage in SLAB
and SLUB code, except for the early_kmem_cache_node_alloc function. This
patch handles that function separately, as it requires to reorder some of
the initialization code to correctly propagate a tagged pointer in case a
tag is assigned by kasan_kmalloc.
Link: http://lkml.kernel.org/r/fc8d0fdcf733a7a52e8d0daaa650f4736a57de8c.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "kasan: add software tag-based mode for arm64", v13.
This patchset adds a new software tag-based mode to KASAN [1]. (Initially
this mode was called KHWASAN, but it got renamed, see the naming rationale
at the end of this section).
The plan is to implement HWASan [2] for the kernel with the incentive,
that it's going to have comparable to KASAN performance, but in the same
time consume much less memory, trading that off for somewhat imprecise bug
detection and being supported only for arm64.
The underlying ideas of the approach used by software tag-based KASAN are:
1. By using the Top Byte Ignore (TBI) arm64 CPU feature, we can store
pointer tags in the top byte of each kernel pointer.
2. Using shadow memory, we can store memory tags for each chunk of kernel
memory.
3. On each memory allocation, we can generate a random tag, embed it into
the returned pointer and set the memory tags that correspond to this
chunk of memory to the same value.
4. By using compiler instrumentation, before each memory access we can add
a check that the pointer tag matches the tag of the memory that is being
accessed.
5. On a tag mismatch we report an error.
With this patchset the existing KASAN mode gets renamed to generic KASAN,
with the word "generic" meaning that the implementation can be supported
by any architecture as it is purely software.
The new mode this patchset adds is called software tag-based KASAN. The
word "tag-based" refers to the fact that this mode uses tags embedded into
the top byte of kernel pointers and the TBI arm64 CPU feature that allows
to dereference such pointers. The word "software" here means that shadow
memory manipulation and tag checking on pointer dereference is done in
software. As it is the only tag-based implementation right now, "software
tag-based" KASAN is sometimes referred to as simply "tag-based" in this
patchset.
A potential expansion of this mode is a hardware tag-based mode, which
would use hardware memory tagging support (announced by Arm [3]) instead
of compiler instrumentation and manual shadow memory manipulation.
Same as generic KASAN, software tag-based KASAN is strictly a debugging
feature.
[1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html
[2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html
[3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a
====== Rationale
On mobile devices generic KASAN's memory usage is significant problem.
One of the main reasons to have tag-based KASAN is to be able to perform a
similar set of checks as the generic one does, but with lower memory
requirements.
Comment from Vishwath Mohan <vishwath@google.com>:
I don't have data on-hand, but anecdotally both ASAN and KASAN have proven
problematic to enable for environments that don't tolerate the increased
memory pressure well. This includes
(a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go,
(c) Connected components like Pixel's visual core [1].
These are both places I'd love to have a low(er) memory footprint option at
my disposal.
Comment from Evgenii Stepanov <eugenis@google.com>:
Looking at a live Android device under load, slab (according to
/proc/meminfo) + kernel stack take 8-10% available RAM (~350MB). KASAN's
overhead of 2x - 3x on top of it is not insignificant.
Not having this overhead enables near-production use - ex. running
KASAN/KHWASAN kernel on a personal, daily-use device to catch bugs that do
not reproduce in test configuration. These are the ones that often cost
the most engineering time to track down.
CPU overhead is bad, but generally tolerable. RAM is critical, in our
experience. Once it gets low enough, OOM-killer makes your life
miserable.
[1] https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/
====== Technical details
Software tag-based KASAN mode is implemented in a very similar way to the
generic one. This patchset essentially does the following:
1. TCR_TBI1 is set to enable Top Byte Ignore.
2. Shadow memory is used (with a different scale, 1:16, so each shadow
byte corresponds to 16 bytes of kernel memory) to store memory tags.
3. All slab objects are aligned to shadow scale, which is 16 bytes.
4. All pointers returned from the slab allocator are tagged with a random
tag and the corresponding shadow memory is poisoned with the same value.
5. Compiler instrumentation is used to insert tag checks. Either by
calling callbacks or by inlining them (CONFIG_KASAN_OUTLINE and
CONFIG_KASAN_INLINE flags are reused).
6. When a tag mismatch is detected in callback instrumentation mode
KASAN simply prints a bug report. In case of inline instrumentation,
clang inserts a brk instruction, and KASAN has it's own brk handler,
which reports the bug.
7. The memory in between slab objects is marked with a reserved tag, and
acts as a redzone.
8. When a slab object is freed it's marked with a reserved tag.
Bug detection is imprecise for two reasons:
1. We won't catch some small out-of-bounds accesses, that fall into the
same shadow cell, as the last byte of a slab object.
2. We only have 1 byte to store tags, which means we have a 1/256
probability of a tag match for an incorrect access (actually even
slightly less due to reserved tag values).
Despite that there's a particular type of bugs that tag-based KASAN can
detect compared to generic KASAN: use-after-free after the object has been
allocated by someone else.
====== Testing
Some kernel developers voiced a concern that changing the top byte of
kernel pointers may lead to subtle bugs that are difficult to discover.
To address this concern deliberate testing has been performed.
It doesn't seem feasible to do some kind of static checking to find
potential issues with pointer tagging, so a dynamic approach was taken.
All pointer comparisons/subtractions have been instrumented in an LLVM
compiler pass and a kernel module that would print a bug report whenever
two pointers with different tags are being compared/subtracted (ignoring
comparisons with NULL pointers and with pointers obtained by casting an
error code to a pointer type) has been used. Then the kernel has been
booted in QEMU and on an Odroid C2 board and syzkaller has been run.
This yielded the following results.
The two places that look interesting are:
is_vmalloc_addr in include/linux/mm.h
is_kernel_rodata in mm/util.c
Here we compare a pointer with some fixed untagged values to make sure
that the pointer lies in a particular part of the kernel address space.
Since tag-based KASAN doesn't add tags to pointers that belong to rodata
or vmalloc regions, this should work as is. To make sure debug checks to
those two functions that check that the result doesn't change whether we
operate on pointers with or without untagging has been added.
A few other cases that don't look that interesting:
Comparing pointers to achieve unique sorting order of pointee objects
(e.g. sorting locks addresses before performing a double lock):
tty_ldisc_lock_pair_timeout in drivers/tty/tty_ldisc.c
pipe_double_lock in fs/pipe.c
unix_state_double_lock in net/unix/af_unix.c
lock_two_nondirectories in fs/inode.c
mutex_lock_double in kernel/events/core.c
ep_cmp_ffd in fs/eventpoll.c
fsnotify_compare_groups fs/notify/mark.c
Nothing needs to be done here, since the tags embedded into pointers
don't change, so the sorting order would still be unique.
Checks that a pointer belongs to some particular allocation:
is_sibling_entry in lib/radix-tree.c
object_is_on_stack in include/linux/sched/task_stack.h
Nothing needs to be done here either, since two pointers can only belong
to the same allocation if they have the same tag.
Overall, since the kernel boots and works, there are no critical bugs.
As for the rest, the traditional kernel testing way (use until fails) is
the only one that looks feasible.
Another point here is that tag-based KASAN is available under a separate
config option that needs to be deliberately enabled. Even though it might
be used in a "near-production" environment to find bugs that are not found
during fuzzing or running tests, it is still a debug tool.
====== Benchmarks
The following numbers were collected on Odroid C2 board. Both generic and
tag-based KASAN were used in inline instrumentation mode.
Boot time [1]:
* ~1.7 sec for clean kernel
* ~5.0 sec for generic KASAN
* ~5.0 sec for tag-based KASAN
Network performance [2]:
* 8.33 Gbits/sec for clean kernel
* 3.17 Gbits/sec for generic KASAN
* 2.85 Gbits/sec for tag-based KASAN
Slab memory usage after boot [3]:
* ~40 kb for clean kernel
* ~105 kb (~260% overhead) for generic KASAN
* ~47 kb (~20% overhead) for tag-based KASAN
KASAN memory overhead consists of three main parts:
1. Increased slab memory usage due to redzones.
2. Shadow memory (the whole reserved once during boot).
3. Quaratine (grows gradually until some preset limit; the more the limit,
the more the chance to detect a use-after-free).
Comparing tag-based vs generic KASAN for each of these points:
1. 20% vs 260% overhead.
2. 1/16th vs 1/8th of physical memory.
3. Tag-based KASAN doesn't require quarantine.
[1] Time before the ext4 driver is initialized.
[2] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`.
[3] Measured as `cat /proc/meminfo | grep Slab`.
====== Some notes
A few notes:
1. The patchset can be found here:
https://github.com/xairy/kasan-prototype/tree/khwasan
2. Building requires a recent Clang version (7.0.0 or later).
3. Stack instrumentation is not supported yet and will be added later.
This patch (of 25):
Tag-based KASAN changes the value of the top byte of pointers returned
from the kernel allocation functions (such as kmalloc). This patch
updates KASAN hooks signatures and their usage in SLAB and SLUB code to
reflect that.
Link: http://lkml.kernel.org/r/aec2b5e3973781ff8a6bb6760f8543643202c451.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "kmalloc-reclaimable caches", v4.
As discussed at LSF/MM [1] here's a patchset that introduces
kmalloc-reclaimable caches (more details in the second patch) and uses
them for dcache external names. That allows us to repurpose the
NR_INDIRECTLY_RECLAIMABLE_BYTES counter later in the series.
With patch 3/6, dcache external names are allocated from kmalloc-rcl-*
caches, eliminating the need for manual accounting. More importantly, it
also ensures the reclaimable kmalloc allocations are grouped in pages
separate from the regular kmalloc allocations. The need for proper
accounting of dcache external names has shown it's easy for misbehaving
process to allocate lots of them, causing premature OOMs. Without the
added grouping, it's likely that a similar workload can interleave the
dcache external names allocations with regular kmalloc allocations (note:
I haven't searched myself for an example of such regular kmalloc
allocation, but I would be very surprised if there wasn't some). A
pathological case would be e.g. one 64byte regular allocations with 63
external dcache names in a page (64x64=4096), which means the page is not
freed even after reclaiming after all dcache names, and the process can
thus "steal" the whole page with single 64byte allocation.
If other kmalloc users similar to dcache external names become identified,
they can also benefit from the new functionality simply by adding
__GFP_RECLAIMABLE to the kmalloc calls.
Side benefits of the patchset (that could be also merged separately)
include removed branch for detecting __GFP_DMA kmalloc(), and shortening
kmalloc cache names in /proc/slabinfo output. The latter is potentially
an ABI break in case there are tools parsing the names and expecting the
values to be in bytes.
This is how /proc/slabinfo looks like after booting in virtme:
...
kmalloc-rcl-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
...
kmalloc-rcl-96 7 32 128 32 1 : tunables 120 60 8 : slabdata 1 1 0
kmalloc-rcl-64 25 128 64 64 1 : tunables 120 60 8 : slabdata 2 2 0
kmalloc-rcl-32 0 0 32 124 1 : tunables 120 60 8 : slabdata 0 0 0
kmalloc-4M 0 0 4194304 1 1024 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-2M 0 0 2097152 1 512 : tunables 1 1 0 : slabdata 0 0 0
kmalloc-1M 0 0 1048576 1 256 : tunables 1 1 0 : slabdata 0 0 0
...
/proc/vmstat with renamed nr_indirectly_reclaimable_bytes counter:
...
nr_slab_reclaimable 2817
nr_slab_unreclaimable 1781
...
nr_kernel_misc_reclaimable 0
...
/proc/meminfo with new KReclaimable counter:
...
Shmem: 564 kB
KReclaimable: 11260 kB
Slab: 18368 kB
SReclaimable: 11260 kB
SUnreclaim: 7108 kB
KernelStack: 1248 kB
...
This patch (of 6):
The kmalloc caches currently mainain separate (optional) array
kmalloc_dma_caches for __GFP_DMA allocations. There are tests for
__GFP_DMA in the allocation hotpaths. We can avoid the branches by
combining kmalloc_caches and kmalloc_dma_caches into a single
two-dimensional array where the outer dimension is cache "type". This
will also allow to add kmalloc-reclaimable caches as a third type.
Link: http://lkml.kernel.org/r/20180731090649.16028-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Extend the slub_debug syntax to "slub_debug=<flags>[,<slub>]*", where
<slub> may contain an asterisk at the end. For example, the following
would poison all kmalloc slabs:
slub_debug=P,kmalloc*
and the following would apply the default flags to all kmalloc and all
block IO slabs:
slub_debug=,bio*,kmalloc*
Please note that a similar patch was posted by Iliyan Malchev some time
ago but was never merged:
https://marc.info/?l=linux-mm&m=131283905330474&w=2
Link: http://lkml.kernel.org/r/20180928111139.27962-1-atomlin@redhat.com
Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Iliyan Malchev <malchev@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Switch to bitmap_zalloc() to show clearly what we are allocating. Besides
that it returns pointer of bitmap type instead of opaque void *.
Link: http://lkml.kernel.org/r/20180830104301.61649-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In SLUB, prefetch_freepointer() is used when allocating an object from
cache's freelist, to make sure the next object in the list is cache-hot,
since it's probable it will be allocated soon.
Commit 2482ddec67 ("mm: add SLUB free list pointer obfuscation") has
unintentionally changed the prefetch in a way where the prefetch is
turned to a real fetch, and only the next->next pointer is prefetched.
In case there is not a stream of allocations that would benefit from
prefetching, the extra real fetch might add a useless cache miss to the
allocation. Restore the previous behavior.
Link: http://lkml.kernel.org/r/20180809085245.22448-1-vbabka@suse.cz
Fixes: 2482ddec67 ("mm: add SLUB free list pointer obfuscation")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In kernel 4.17 I removed some code from dm-bufio that did slab cache
merging (commit 21bb13276768: "dm bufio: remove code that merges slab
caches") - both slab and slub support merging caches with identical
attributes, so dm-bufio now just calls kmem_cache_create and relies on
implicit merging.
This uncovered a bug in the slub subsystem - if we delete a cache and
immediatelly create another cache with the same attributes, it fails
because of duplicate filename in /sys/kernel/slab/. The slub subsystem
offloads freeing the cache to a workqueue - and if we create the new
cache before the workqueue runs, it complains because of duplicate
filename in sysfs.
This patch fixes the bug by moving the call of kobject_del from
sysfs_slab_remove_workfn to shutdown_cache. kobject_del must be called
while we hold slab_mutex - so that the sysfs entry is deleted before a
cache with the same attributes could be created.
Running device-mapper-test-suite with:
dmtest run --suite thin-provisioning -n /commit_failure_causes_fallback/
triggered:
Buffer I/O error on dev dm-0, logical block 1572848, async page read
device-mapper: thin: 253:1: metadata operation 'dm_pool_alloc_data_block' failed: error = -5
device-mapper: thin: 253:1: aborting current metadata transaction
sysfs: cannot create duplicate filename '/kernel/slab/:a-0000144'
CPU: 2 PID: 1037 Comm: kworker/u48:1 Not tainted 4.17.0.snitm+ #25
Hardware name: Supermicro SYS-1029P-WTR/X11DDW-L, BIOS 2.0a 12/06/2017
Workqueue: dm-thin do_worker [dm_thin_pool]
Call Trace:
dump_stack+0x5a/0x73
sysfs_warn_dup+0x58/0x70
sysfs_create_dir_ns+0x77/0x80
kobject_add_internal+0xba/0x2e0
kobject_init_and_add+0x70/0xb0
sysfs_slab_add+0xb1/0x250
__kmem_cache_create+0x116/0x150
create_cache+0xd9/0x1f0
kmem_cache_create_usercopy+0x1c1/0x250
kmem_cache_create+0x18/0x20
dm_bufio_client_create+0x1ae/0x410 [dm_bufio]
dm_block_manager_create+0x5e/0x90 [dm_persistent_data]
__create_persistent_data_objects+0x38/0x940 [dm_thin_pool]
dm_pool_abort_metadata+0x64/0x90 [dm_thin_pool]
metadata_operation_failed+0x59/0x100 [dm_thin_pool]
alloc_data_block.isra.53+0x86/0x180 [dm_thin_pool]
process_cell+0x2a3/0x550 [dm_thin_pool]
do_worker+0x28d/0x8f0 [dm_thin_pool]
process_one_work+0x171/0x370
worker_thread+0x49/0x3f0
kthread+0xf8/0x130
ret_from_fork+0x35/0x40
kobject_add_internal failed for :a-0000144 with -EEXIST, don't try to register things with the same name in the same directory.
kmem_cache_create(dm_bufio_buffer-16) failed with error -17
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1806151817130.6333@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-by: Mike Snitzer <snitzer@redhat.com>
Tested-by: Mike Snitzer <snitzer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Christoph doubts anyone was using the 'reserved' file in sysfs, so remove
it.
Link: http://lkml.kernel.org/r/20180518194519.3820-17-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The reserved field was only used for embedding an rcu_head in the data
structure. With the previous commit, we no longer need it. That lets us
remove the 'reserved' argument to a lot of functions.
Link: http://lkml.kernel.org/r/20180518194519.3820-16-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
rcu_head may now grow larger than list_head without affecting slab or
slub.
Link: http://lkml.kernel.org/r/20180518194519.3820-15-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since the LRU is two words, this does not affect the double-word alignment
of SLUB's freelist.
Link: http://lkml.kernel.org/r/20180518194519.3820-10-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
By moving page->private to the fourth word of struct page, we can put the
SLUB counters in the same word as SLAB's s_mem and still do the
cmpxchg_double trick. Now the SLUB counters no longer overlap with the
mapcount or refcount so we can drop the call to page_mapcount_reset() and
simplify set_page_slub_counters() to a single line.
Link: http://lkml.kernel.org/r/20180518194519.3820-6-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This will allow us to store slub's counters in the same bits as slab's
s_mem. slub now needs to set page->mapping to NULL as it frees the page,
just like slab does.
Link: http://lkml.kernel.org/r/20180518194519.3820-5-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The obsolete comment removed in this patch was introduced by
51df114281 ("slub: Dynamically size kmalloc cache allocations").
I paste related modification from that commit:
+#ifdef CONFIG_NUMA
+ /*
+ * Allocate kmem_cache_node properly from the kmem_cache slab.
+ * kmem_cache_node is separately allocated so no need to
+ * update any list pointers.
+ */
+ temp_kmem_cache_node = kmem_cache_node;
+ kmem_cache_node = kmem_cache_alloc(kmem_cache, GFP_NOWAIT);
+ memcpy(kmem_cache_node, temp_kmem_cache_node, kmem_size);
+
+ kmem_cache_bootstrap_fixup(kmem_cache_node);
+
+ caches++;
+#else
+ /*
+ * kmem_cache has kmem_cache_node embedded and we moved it!
+ * Update the list heads
+ */
+ INIT_LIST_HEAD(&kmem_cache->local_node.partial);
+ list_splice(&temp_kmem_cache->local_node.partial, &kmem_cache->local_node.partial);
+#ifdef CONFIG_SLUB_DEBUG
+ INIT_LIST_HEAD(&kmem_cache->local_node.full);
+ list_splice(&temp_kmem_cache->local_node.full, &kmem_cache->local_node.full);
+#endif
As we can see there're used to distinguish the difference handling
between NUMA/non-NUMA configuration in the original commit. I think it
doesn't make any sense in current implementation which is placed above
kmem_cache_node = bootstrap(&boot_kmem_cache_node); So maybe it's better
to remove them now?
Link: http://lkml.kernel.org/r/5af26f58.1c69fb81.1be0e.c520SMTPIN_ADDED_BROKEN@mx.google.com
Signed-off-by: Canjiang Lu <canjiang.lu@samsung.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__printf is useful to verify format and arguments. Remove the following
warning (with W=1):
mm/slub.c:721:2: warning: function might be possible candidate for `gnu_printf' format attribute [-Wsuggest-attribute=format]
Link: http://lkml.kernel.org/r/20180505200706.19986-1-malat@debian.org
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__GFP_ZERO requests that the object be initialised to all-zeroes, while
the purpose of a constructor is to initialise an object to a particular
pattern. We cannot do both. Add a warning to catch any users who
mistakenly pass a __GFP_ZERO flag when allocating a slab with a
constructor.
Link: http://lkml.kernel.org/r/20180412191322.GA21205@bombadil.infradead.org
Fixes: d07dbea464 ("Slab allocators: support __GFP_ZERO in all allocators")
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kasan_slab_free hook's return value denotes whether the reuse of a
slab object must be delayed (e.g. when the object is put into memory
qurantine).
The current way SLUB handles this hook is by ignoring its return value
and hardcoding checks similar (but not exactly the same) to the ones
performed in kasan_slab_free, which is prone to making mistakes.
The main difference between the hardcoded checks and the ones in
kasan_slab_free is whether we want to perform a free in case when an
invalid-free or a double-free was detected (we don't).
This patch changes the way SLUB handles this by:
1. taking into account the return value of kasan_slab_free for each of
the objects, that are being freed;
2. reconstructing the freelist of objects to exclude the ones, whose
reuse must be delayed.
[andreyknvl@google.com: eliminate unnecessary branch in slab_free]
Link: http://lkml.kernel.org/r/a62759a2545fddf69b0c034547212ca1eb1b3ce2.1520359686.git.andreyknvl@google.com
Link: http://lkml.kernel.org/r/083f58501e54731203801d899632d76175868e97.1519400992.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kasan quarantine is designed to delay freeing slab objects to catch
use-after-free. The quarantine can be large (several percent of machine
memory size). When kmem_caches are deleted related objects are flushed
from the quarantine but this requires scanning the entire quarantine
which can be very slow. We have seen the kernel busily working on this
while holding slab_mutex and badly affecting cache_reaper, slabinfo
readers and memcg kmem cache creations.
It can easily reproduced by following script:
yes . | head -1000000 | xargs stat > /dev/null
for i in `seq 1 10`; do
seq 500 | (cd /cg/memory && xargs mkdir)
seq 500 | xargs -I{} sh -c 'echo $BASHPID > \
/cg/memory/{}/tasks && exec stat .' > /dev/null
seq 500 | (cd /cg/memory && xargs rmdir)
done
The busy stack:
kasan_cache_shutdown
shutdown_cache
memcg_destroy_kmem_caches
mem_cgroup_css_free
css_free_rwork_fn
process_one_work
worker_thread
kthread
ret_from_fork
This patch is based on the observation that if the kmem_cache to be
destroyed is empty then there should not be any objects of this cache in
the quarantine.
Without the patch the script got stuck for couple of hours. With the
patch the script completed within a second.
Link: http://lkml.kernel.org/r/20180327230603.54721-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Function returns size of the object without red zone which can't be
negative.
Link: http://lkml.kernel.org/r/20180305200730.15812-24-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
struct kmem_cache_order_objects is for mixing order and number of
objects, and orders aren't big enough to warrant 64-bit width.
Propagate unsignedness down so that everything fits.
!!! Patch assumes that "PAGE_SIZE << order" doesn't overflow. !!!
Link: http://lkml.kernel.org/r/20180305200730.15812-23-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
slab_index() returns index of an object within a slab which is at most
u15 (or u16?).
Iterators additionally guarantee that "p >= addr".
Link: http://lkml.kernel.org/r/20180305200730.15812-22-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If kmem case sizes are 32-bit, then usecopy region should be too.
Link: http://lkml.kernel.org/r/20180305200730.15812-21-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If SLAB doesn't support 4GB+ kmem caches (it never did), KASAN should
not do it as well.
Link: http://lkml.kernel.org/r/20180305200730.15812-20-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that all sizes are properly typed, propagate "unsigned int" down the
callgraph.
Link: http://lkml.kernel.org/r/20180305200730.15812-19-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux doesn't support negative length objects (including meta data).
Link: http://lkml.kernel.org/r/20180305200730.15812-18-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
/*
* cpu_partial determined the maximum number of objects
* kept in the per cpu partial lists of a processor.
*/
Can't be negative.
Link: http://lkml.kernel.org/r/20180305200730.15812-15-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
->inuse is "the number of bytes in actual use by the object",
can't be negative.
Link: http://lkml.kernel.org/r/20180305200730.15812-14-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
->reserved is either 0 or sizeof(struct rcu_head), can't be negative.
Link: http://lkml.kernel.org/r/20180305200730.15812-12-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
->remote_node_defrag_ratio is in range 0..1000.
This also adds a check and modifies the behavior to return an error
code. Before this patch invalid values were ignored.
Link: http://lkml.kernel.org/r/20180305200730.15812-9-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
struct kmem_cache::size and ::align were always 32-bit.
Out of curiosity I created 4GB kmem_cache, it oopsed with division by 0.
kmem_cache_create(1UL<<32+1) created 1-byte cache as expected.
size_t doesn't work and never did.
Link: http://lkml.kernel.org/r/20180305200730.15812-6-adobriyan@gmail.com
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When SLUB_DEBUG catches some issues, it prints all the required debug
info. However, in a few cases where allocation and free of the object
has happened in a very short time, 'age' might be misleading. See the
example below:
=============================================================================
BUG kmalloc-256 (Tainted: G W O ): Poison overwritten
-----------------------------------------------------------------------------
...
INFO: Allocated in binder_transaction+0x4b0/0x2448 age=731 cpu=3 pid=5314
...
INFO: Freed in binder_free_transaction+0x2c/0x58 age=735 cpu=6 pid=2079
...
Object fffffff14956a870: 6b 6b 6b 6b 6b 6b 6b 6b 67 6b 6b 6b 6b 6b 6b a5 kkkkkkkkgkkkk
In this case, object got freed later but 'age' shows otherwise. This
could be because, while printing this info, we print allocation traces
first and free traces thereafter. In between, if we get schedule out or
jiffies increment, (jiffies - t->when) could become meaningless.
Use the jitter free reference to calculate age.
New output will exactly be same. 'age' is still staying with single
jiffies ref in both prints.
Change-Id: I0846565807a4229748649bbecb1ffb743d71fcd8
Link: http://lkml.kernel.org/r/1520492010-19389-1-git-send-email-cpandya@codeaurora.org
Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__builtin_return_address(1) is unreliable without frame pointers.
With defconfig on kmalloc_pagealloc_invalid_free test I am getting:
BUG: KASAN: double-free or invalid-free in (null)
Pass caller PC from callers explicitly.
Link: http://lkml.kernel.org/r/9b01bc2d237a4df74ff8472a3bf6b7635908de01.1514378558.git.dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>a
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "kasan: detect invalid frees".
KASAN detects double-frees, but does not detect invalid-frees (when a
pointer into a middle of heap object is passed to free). We recently had
a very unpleasant case in crypto code which freed an inner object inside
of a heap allocation. This left unnoticed during free, but totally
corrupted heap and later lead to a bunch of random crashes all over kernel
code.
Detect invalid frees.
This patch (of 5):
Detect frees of pointers into middle of large heap objects.
I dropped const from kasan_kfree_large() because it starts propagating
through a bunch of functions in kasan_report.c, slab/slub nearest_obj(),
all of their local variables, fixup_red_left(), etc.
Link: http://lkml.kernel.org/r/1b45b4fe1d20fc0de1329aab674c1dd973fee723.1514378558.git.dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>a
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cache objects. This is good, but still leaves a lot of kernel memory
available to be copied to/from userspace in the face of bugs. To further
restrict what memory is available for copying, this creates a way to
whitelist specific areas of a given slab cache object for copying to/from
userspace, allowing much finer granularity of access control. Slab caches
that are never exposed to userspace can declare no whitelist for their
objects, thereby keeping them unavailable to userspace via dynamic copy
operations. (Note, an implicit form of whitelisting is the use of constant
sizes in usercopy operations and get_user()/put_user(); these bypass all
hardened usercopy checks since these sizes cannot change at runtime.)
This new check is WARN-by-default, so any mistakes can be found over the
next several releases without breaking anyone's system.
The series has roughly the following sections:
- remove %p and improve reporting with offset
- prepare infrastructure and whitelist kmalloc
- update VFS subsystem with whitelists
- update SCSI subsystem with whitelists
- update network subsystem with whitelists
- update process memory with whitelists
- update per-architecture thread_struct with whitelists
- update KVM with whitelists and fix ioctl bug
- mark all other allocations as not whitelisted
- update lkdtm for more sensible test overage
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Merge tag 'usercopy-v4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull hardened usercopy whitelisting from Kees Cook:
"Currently, hardened usercopy performs dynamic bounds checking on slab
cache objects. This is good, but still leaves a lot of kernel memory
available to be copied to/from userspace in the face of bugs.
To further restrict what memory is available for copying, this creates
a way to whitelist specific areas of a given slab cache object for
copying to/from userspace, allowing much finer granularity of access
control.
Slab caches that are never exposed to userspace can declare no
whitelist for their objects, thereby keeping them unavailable to
userspace via dynamic copy operations. (Note, an implicit form of
whitelisting is the use of constant sizes in usercopy operations and
get_user()/put_user(); these bypass all hardened usercopy checks since
these sizes cannot change at runtime.)
This new check is WARN-by-default, so any mistakes can be found over
the next several releases without breaking anyone's system.
The series has roughly the following sections:
- remove %p and improve reporting with offset
- prepare infrastructure and whitelist kmalloc
- update VFS subsystem with whitelists
- update SCSI subsystem with whitelists
- update network subsystem with whitelists
- update process memory with whitelists
- update per-architecture thread_struct with whitelists
- update KVM with whitelists and fix ioctl bug
- mark all other allocations as not whitelisted
- update lkdtm for more sensible test overage"
* tag 'usercopy-v4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (38 commits)
lkdtm: Update usercopy tests for whitelisting
usercopy: Restrict non-usercopy caches to size 0
kvm: x86: fix KVM_XEN_HVM_CONFIG ioctl
kvm: whitelist struct kvm_vcpu_arch
arm: Implement thread_struct whitelist for hardened usercopy
arm64: Implement thread_struct whitelist for hardened usercopy
x86: Implement thread_struct whitelist for hardened usercopy
fork: Provide usercopy whitelisting for task_struct
fork: Define usercopy region in thread_stack slab caches
fork: Define usercopy region in mm_struct slab caches
net: Restrict unwhitelisted proto caches to size 0
sctp: Copy struct sctp_sock.autoclose to userspace using put_user()
sctp: Define usercopy region in SCTP proto slab cache
caif: Define usercopy region in caif proto slab cache
ip: Define usercopy region in IP proto slab cache
net: Define usercopy region in struct proto slab cache
scsi: Define usercopy region in scsi_sense_cache slab cache
cifs: Define usercopy region in cifs_request slab cache
vxfs: Define usercopy region in vxfs_inode slab cache
ufs: Define usercopy region in ufs_inode_cache slab cache
...
Commit d6e0b7fa11 ("slub: make dead caches discard free slabs
immediately") makes put_cpu_partial() run with preemption disabled and
interrupts disabled when calling unfreeze_partials().
The comment: "put_cpu_partial() is done without interrupts disabled and
without preemption disabled" looks obsolete, so remove it.
Link: http://lkml.kernel.org/r/1516968550-1520-1-git-send-email-miles.chen@mediatek.com
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Start address calculated for slab padding restoration was wrong. Wrong
address would point to some section before padding and could cause
corruption
Link: http://lkml.kernel.org/r/1516604578-4577-1-git-send-email-balasubramani_vivekanandan@mentor.com
Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan@mentor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This introduces CONFIG_HARDENED_USERCOPY_FALLBACK to control the
behavior of hardened usercopy whitelist violations. By default, whitelist
violations will continue to WARN() so that any bad or missing usercopy
whitelists can be discovered without being too disruptive.
If this config is disabled at build time or a system is booted with
"slab_common.usercopy_fallback=0", usercopy whitelists will BUG() instead
of WARN(). This is useful for admins that want to use usercopy whitelists
immediately.
Suggested-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
This patch adds checking of usercopy cache whitelisting, and is modified
from Brad Spengler/PaX Team's PAX_USERCOPY whitelisting code in the
last public patch of grsecurity/PaX based on my understanding of the
code. Changes or omissions from the original code are mine and don't
reflect the original grsecurity/PaX code.
The SLAB and SLUB allocators are modified to WARN() on all copy operations
in which the kernel heap memory being modified falls outside of the cache's
defined usercopy region.
Based on an earlier patch from David Windsor.
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
This patch prepares the slab allocator to handle caches having annotations
(useroffset and usersize) defining usercopy regions.
This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on
my understanding of the code. Changes or omissions from the original
code are mine and don't reflect the original grsecurity/PaX code.
Currently, hardened usercopy performs dynamic bounds checking on slab
cache objects. This is good, but still leaves a lot of kernel memory
available to be copied to/from userspace in the face of bugs. To further
restrict what memory is available for copying, this creates a way to
whitelist specific areas of a given slab cache object for copying to/from
userspace, allowing much finer granularity of access control. Slab caches
that are never exposed to userspace can declare no whitelist for their
objects, thereby keeping them unavailable to userspace via dynamic copy
operations. (Note, an implicit form of whitelisting is the use of constant
sizes in usercopy operations and get_user()/put_user(); these bypass
hardened usercopy checks since these sizes cannot change at runtime.)
To support this whitelist annotation, usercopy region offset and size
members are added to struct kmem_cache. The slab allocator receives a
new function, kmem_cache_create_usercopy(), that creates a new cache
with a usercopy region defined, suitable for declaring spans of fields
within the objects that get copied to/from userspace.
In this patch, the default kmem_cache_create() marks the entire allocation
as whitelisted, leaving it semantically unchanged. Once all fine-grained
whitelists have been added (in subsequent patches), this will be changed
to a usersize of 0, making caches created with kmem_cache_create() not
copyable to/from userspace.
After the entire usercopy whitelist series is applied, less than 15%
of the slab cache memory remains exposed to potential usercopy bugs
after a fresh boot:
Total Slab Memory: 48074720
Usercopyable Memory: 6367532 13.2%
task_struct 0.2% 4480/1630720
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 269760/8740224
dentry 11.1% 585984/5273856
mm_struct 29.1% 54912/188448
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 81920/81920
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 167936/167936
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 455616/455616
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 812032/812032
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1310720/1310720
After some kernel build workloads, the percentage (mainly driven by
dentry and inode caches expanding) drops under 10%:
Total Slab Memory: 95516184
Usercopyable Memory: 8497452 8.8%
task_struct 0.2% 4000/1456000
RAW 0.3% 300/96000
RAWv6 2.1% 1408/64768
ext4_inode_cache 3.0% 1217280/39439872
dentry 11.1% 1623200/14608800
mm_struct 29.1% 73216/251264
kmalloc-8 100.0% 24576/24576
kmalloc-16 100.0% 28672/28672
kmalloc-32 100.0% 94208/94208
kmalloc-192 100.0% 96768/96768
kmalloc-128 100.0% 143360/143360
names_cache 100.0% 163840/163840
kmalloc-64 100.0% 245760/245760
kmalloc-256 100.0% 339968/339968
kmalloc-512 100.0% 350720/350720
kmalloc-96 100.0% 563520/563520
kmalloc-8192 100.0% 655360/655360
kmalloc-1024 100.0% 794624/794624
kmalloc-4096 100.0% 819200/819200
kmalloc-2048 100.0% 1257472/1257472
Signed-off-by: David Windsor <dave@nullcore.net>
[kees: adjust commit log, split out a few extra kmalloc hunks]
[kees: add field names to function declarations]
[kees: convert BUGs to WARNs and fail closed]
[kees: add attack surface reduction analysis to commit log]
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Christoph Lameter <cl@linux.com>
This refactors the hardened usercopy code so that failure reporting can
happen within the checking functions instead of at the top level. This
simplifies the return value handling and allows more details and offsets
to be included in the report. Having the offset can be much more helpful
in understanding hardened usercopy bugs.
Signed-off-by: Kees Cook <keescook@chromium.org>
Now that kmemcheck is gone, we don't need the NOTRACK flags.
Link: http://lkml.kernel.org/r/20171007030159.22241-5-alexander.levin@verizon.com
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tim Hansen <devtimhansen@gmail.com>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert all allocations that used a NOTRACK flag to stop using it.
Link: http://lkml.kernel.org/r/20171007030159.22241-3-alexander.levin@verizon.com
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tim Hansen <devtimhansen@gmail.com>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "kmemcheck: kill kmemcheck", v2.
As discussed at LSF/MM, kill kmemcheck.
KASan is a replacement that is able to work without the limitation of
kmemcheck (single CPU, slow). KASan is already upstream.
We are also not aware of any users of kmemcheck (or users who don't
consider KASan as a suitable replacement).
The only objection was that since KASAN wasn't supported by all GCC
versions provided by distros at that time we should hold off for 2
years, and try again.
Now that 2 years have passed, and all distros provide gcc that supports
KASAN, kill kmemcheck again for the very same reasons.
This patch (of 4):
Remove kmemcheck annotations, and calls to kmemcheck from the kernel.
[alexander.levin@verizon.com: correctly remove kmemcheck call from dma_map_sg_attrs]
Link: http://lkml.kernel.org/r/20171012192151.26531-1-alexander.levin@verizon.com
Link: http://lkml.kernel.org/r/20171007030159.22241-2-alexander.levin@verizon.com
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tim Hansen <devtimhansen@gmail.com>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When slub_debug=O is set. It is possible to clear debug flags for an
"unmergeable" slab cache in kmem_cache_open(). It makes the "unmergeable"
cache became "mergeable" in sysfs_slab_add().
These caches will generate their "unique IDs" by create_unique_id(), but
it is possible to create identical unique IDs. In my experiment,
sgpool-128, names_cache, biovec-256 generate the same ID ":Ft-0004096" and
the kernel reports "sysfs: cannot create duplicate filename
'/kernel/slab/:Ft-0004096'".
To repeat my experiment, set disable_higher_order_debug=1,
CONFIG_SLUB_DEBUG_ON=y in kernel-4.14.
Fix this issue by setting unmergeable=1 if slub_debug=O and the the
default slub_debug contains any no-merge flags.
call path:
kmem_cache_create()
__kmem_cache_alias() -> we set SLAB_NEVER_MERGE flags here
create_cache()
__kmem_cache_create()
kmem_cache_open() -> clear DEBUG_METADATA_FLAGS
sysfs_slab_add() -> the slab cache is mergeable now
sysfs: cannot create duplicate filename '/kernel/slab/:Ft-0004096'
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x60/0x7c
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.14.0-rc7ajb-00131-gd4c2e9f-dirty #123
Hardware name: linux,dummy-virt (DT)
task: ffffffc07d4e0080 task.stack: ffffff8008008000
PC is at sysfs_warn_dup+0x60/0x7c
LR is at sysfs_warn_dup+0x60/0x7c
pc : lr : pstate: 60000145
Call trace:
sysfs_warn_dup+0x60/0x7c
sysfs_create_dir_ns+0x98/0xa0
kobject_add_internal+0xa0/0x294
kobject_init_and_add+0x90/0xb4
sysfs_slab_add+0x90/0x200
__kmem_cache_create+0x26c/0x438
kmem_cache_create+0x164/0x1f4
sg_pool_init+0x60/0x100
do_one_initcall+0x38/0x12c
kernel_init_freeable+0x138/0x1d4
kernel_init+0x10/0xfc
ret_from_fork+0x10/0x18
Link: http://lkml.kernel.org/r/1510365805-5155-1-git-send-email-miles.chen@mediatek.com
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds