All existing users of %pGp want the hex value as well as the decoded
flag names. This looks awkward (passing the same parameter to printf
twice), so move that functionality into the core. If we want, we
can make that optional with flag arguments to %pGp in the future.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20211019142621.2810043-6-willy@infradead.org
When sysfs_slab_add failed, we shouldn't call debugfs_slab_add() for s
because s will be freed soon. And slab_debugfs_fops will use s later
leading to a use-after-free.
Link: https://lkml.kernel.org/r/20210916123920.48704-5-linmiaohe@huawei.com
Fixes: 64dd68497b ("mm: slub: move sysfs slab alloc/free interfaces to debugfs")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Pekka Enberg <penberg@kernel.org>
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>
In error path, the random_seq of slub cache might be leaked. Fix this
by using __kmem_cache_release() to release all the relevant resources.
Link: https://lkml.kernel.org/r/20210916123920.48704-4-linmiaohe@huawei.com
Fixes: 210e7a43fa ("mm: SLUB freelist randomization")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Pekka Enberg <penberg@kernel.org>
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>
If object's reuse is delayed, it will be excluded from the reconstructed
freelist. But we forgot to adjust the cnt accordingly. So there will
be a mismatch between reconstructed freelist depth and cnt. This will
lead to free_debug_processing() complaining about freelist count or a
incorrect slub inuse count.
Link: https://lkml.kernel.org/r/20210916123920.48704-3-linmiaohe@huawei.com
Fixes: c3895391df ("kasan, slub: fix handling of kasan_slab_free hook")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Pekka Enberg <penberg@kernel.org>
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 "Fixups for slub".
This series contains various bug fixes for slub. We fix memoryleak,
use-afer-free, NULL pointer dereferencing and so on in slub. More
details can be found in the respective changelogs.
This patch (of 5):
It's possible that __seq_open_private() will return NULL. So we should
check it before using lest dereferencing NULL pointer. And in error
paths, we forgot to release private buffer via seq_release_private().
Memory will leak in these paths.
Link: https://lkml.kernel.org/r/20210916123920.48704-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20210916123920.48704-2-linmiaohe@huawei.com
Fixes: 64dd68497b ("mm: slub: move sysfs slab alloc/free interfaces to debugfs")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-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: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Bharata B Rao <bharata@linux.ibm.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>
Embed local_lock into struct kmem_cpu_slab and use the irq-safe versions of
local_lock instead of plain local_irq_save/restore. On !PREEMPT_RT that's
equivalent, with better lockdep visibility. On PREEMPT_RT that means better
preemption.
However, the cost on PREEMPT_RT is the loss of lockless fast paths which only
work with cpu freelist. Those are designed to detect and recover from being
preempted by other conflicting operations (both fast or slow path), but the
slow path operations assume they cannot be preempted by a fast path operation,
which is guaranteed naturally with disabled irqs. With local locks on
PREEMPT_RT, the fast paths now also need to take the local lock to avoid races.
In the allocation fastpath slab_alloc_node() we can just defer to the slowpath
__slab_alloc() which also works with cpu freelist, but under the local lock.
In the free fastpath do_slab_free() we have to add a new local lock protected
version of freeing to the cpu freelist, as the existing slowpath only works
with the page freelist.
Also update the comment about locking scheme in SLUB to reflect changes done
by this series.
[ Mike Galbraith <efault@gmx.de>: use local_lock() without irq in PREEMPT_RT
scope; debugging of RT crashes resulting in put_cpu_partial() locking changes ]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
We currently use preempt_disable() (directly or via get_cpu_ptr()) to stabilize
the pointer to kmem_cache_cpu. On PREEMPT_RT this would be incompatible with
the list_lock spinlock. We can use migrate_disable() instead, but that
increases overhead on !PREEMPT_RT as it's an unconditional function call.
In order to get the best available mechanism on both PREEMPT_RT and
!PREEMPT_RT, introduce private slub_get_cpu_ptr() and slub_put_cpu_ptr()
wrappers and use them.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Jann Horn reported [1] the following theoretically possible race:
task A: put_cpu_partial() calls preempt_disable()
task A: oldpage = this_cpu_read(s->cpu_slab->partial)
interrupt: kfree() reaches unfreeze_partials() and discards the page
task B (on another CPU): reallocates page as page cache
task A: reads page->pages and page->pobjects, which are actually
halves of the pointer page->lru.prev
task B (on another CPU): frees page
interrupt: allocates page as SLUB page and places it on the percpu partial list
task A: this_cpu_cmpxchg() succeeds
which would cause page->pages and page->pobjects to end up containing
halves of pointers that would then influence when put_cpu_partial()
happens and show up in root-only sysfs files. Maybe that's acceptable,
I don't know. But there should probably at least be a comment for now
to point out that we're reading union fields of a page that might be
in a completely different state.
Additionally, the this_cpu_cmpxchg() approach in put_cpu_partial() is only safe
against s->cpu_slab->partial manipulation in ___slab_alloc() if the latter
disables irqs, otherwise a __slab_free() in an irq handler could call
put_cpu_partial() in the middle of ___slab_alloc() manipulating ->partial
and corrupt it. This becomes an issue on RT after a local_lock is introduced
in later patch. The fix means taking the local_lock also in put_cpu_partial()
on RT.
After debugging this issue, Mike Galbraith suggested [2] that to avoid
different locking schemes on RT and !RT, we can just protect put_cpu_partial()
with disabled irqs (to be converted to local_lock_irqsave() later) everywhere.
This should be acceptable as it's not a fast path, and moving the actual
partial unfreezing outside of the irq disabled section makes it short, and with
the retry loop gone the code can be also simplified. In addition, the race
reported by Jann should no longer be possible.
[1] https://lore.kernel.org/lkml/CAG48ez1mvUuXwg0YPH5ANzhQLpbphqk-ZS+jbRz+H66fvm4FcA@mail.gmail.com/
[2] https://lore.kernel.org/linux-rt-users/e3470ab357b48bccfbd1f5133b982178a7d2befb.camel@gmx.de/
Reported-by: Jann Horn <jannh@google.com>
Suggested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
We need to disable irqs around slab_lock() (a bit spinlock) to make it
irq-safe. Most calls to slab_lock() are nested under spin_lock_irqsave() which
doesn't disable irqs on PREEMPT_RT, so add explicit disabling with PREEMPT_RT.
The exception is cmpxchg_double_slab() which already disables irqs, so use a
__slab_[un]lock() variant without irq disable there.
slab_[un]lock() thus needs a flags pointer parameter, which is unused on !RT.
free_debug_processing() now has two flags variables, which looks odd, but only
one is actually used - the one used in spin_lock_irqsave() on !RT and the one
used in slab_lock() on RT.
As a result, __cmpxchg_double_slab() and cmpxchg_double_slab() become
effectively identical on RT, as both will disable irqs, which is necessary on
RT as most callers of this function also rely on irqsaving lock operations.
Thus, assert that irqs are already disabled in __cmpxchg_double_slab() only on
!RT and also change the VM_BUG_ON assertion to the more standard lockdep_assert
one.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
The variable object_map is protected by object_map_lock. The lock is always
acquired in debug code and within already atomic context
Make object_map_lock a raw_spinlock_t.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
flush_all() flushes a specific SLAB cache on each CPU (where the cache
is present). The deactivate_slab()/__free_slab() invocation happens
within IPI handler and is problematic for PREEMPT_RT.
The flush operation is not a frequent operation or a hot path. The
per-CPU flush operation can be moved to within a workqueue.
Because a workqueue handler, unlike IPI handler, does not disable irqs,
flush_slab() now has to disable them for working with the kmem_cache_cpu
fields. deactivate_slab() is safe to call with irqs enabled.
[vbabka@suse.cz: adapt to new SLUB changes]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
flush_slab() is called either as part IPI handler on given live cpu, or as a
cleanup on behalf of another cpu that went offline. The first case needs to
protect updating the kmem_cache_cpu fields with disabled irqs. Currently the
whole call happens with irqs disabled by the IPI handler, but the following
patch will change from IPI to workqueue, and flush_slab() will have to disable
irqs (to be replaced with a local lock later) in the critical part.
To prepare for this change, replace the call to flush_slab() for the dead cpu
handling with an opencoded variant that will not disable irqs nor take a local
lock.
Suggested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
slub_cpu_dead() cleans up for an offlined cpu from another cpu and calls only
functions that are now irq safe, so we don't need to disable irqs anymore.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
__unfreeze_partials() no longer needs to have irqs disabled, except for making
the spin_lock operations irq-safe, so convert the spin_locks operations and
remove the separate irq handling.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Unfreezing partial list can be split to two phases - detaching the list from
struct kmem_cache_cpu, and processing the list. The whole operation does not
need to be protected by disabled irqs. Restructure the code to separate the
detaching (with disabled irqs) and unfreezing (with irq disabling to be reduced
in the next patch).
Also, unfreeze_partials() can be called from another cpu on behalf of a cpu
that is being offlined, where disabling irqs on the local cpu has no sense, so
restructure the code as follows:
- __unfreeze_partials() is the bulk of unfreeze_partials() that processes the
detached percpu partial list
- unfreeze_partials() detaches list from current cpu with irqs disabled and
calls __unfreeze_partials()
- unfreeze_partials_cpu() is to be called for the offlined cpu so it needs no
irq disabling, and is called from __flush_cpu_slab()
- flush_cpu_slab() is for the local cpu thus it needs to call
unfreeze_partials(). So it can't simply call
__flush_cpu_slab(smp_processor_id()) anymore and we have to open-code the
proper calls.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Instead of iterating through the live percpu partial list, detach it from the
kmem_cache_cpu at once. This is simpler and will allow further optimization.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
unfreeze_partials() can be optimized so that it doesn't need irqs disabled for
the whole time. As the first step, move irq control into the function and
remove it from the put_cpu_partial() caller.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
The function is now safe to be called with irqs enabled, so move the calls
outside of irq disabled sections.
When called from ___slab_alloc() -> flush_slab() we have irqs disabled, so to
reenable them before deactivate_slab() we need to open-code flush_slab() in
___slab_alloc() and reenable irqs after modifying the kmem_cache_cpu fields.
But that means a IRQ handler meanwhile might have assigned a new page to
kmem_cache_cpu.page so we have to retry the whole check.
The remaining callers of flush_slab() are the IPI handler which has disabled
irqs anyway, and slub_cpu_dead() which will be dealt with in the following
patch.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
dectivate_slab() now no longer touches the kmem_cache_cpu structure, so it will
be possible to call it with irqs enabled. Just convert the spin_lock calls to
their irq saving/restoring variants to make it irq-safe.
Note we now have to use cmpxchg_double_slab() for irq-safe slab_lock(), because
in some situations we don't take the list_lock, which would disable irqs.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
deactivate_slab() removes the cpu slab by merging the cpu freelist with slab's
freelist and putting the slab on the proper node's list. It also sets the
respective kmem_cache_cpu pointers to NULL.
By extracting the kmem_cache_cpu operations from the function, we can make it
not dependent on disabled irqs.
Also if we return a single free pointer from ___slab_alloc, we no longer have
to assign kmem_cache_cpu.page before deactivation or care if somebody preempted
us and assigned a different page to our kmem_cache_cpu in the process.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
The function get_partial() does not need to have irqs disabled as a whole. It's
sufficient to convert spin_lock operations to their irq saving/restoring
versions.
As a result, it's now possible to reach the page allocator from the slab
allocator without disabling and re-enabling interrupts on the way.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Building on top of the previous patch, re-enable irqs before checking new
pages. alloc_debug_processing() is now called with enabled irqs so we need to
remove VM_BUG_ON(!irqs_disabled()); in check_slab() - there doesn't seem to be
a need for it anyway.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
When we obtain a new slab page from node partial list or page allocator, we
assign it to kmem_cache_cpu, perform some checks, and if they fail, we undo
the assignment.
In order to allow doing the checks without irq disabled, restructure the code
so that the checks are done first, and kmem_cache_cpu.page assignment only
after they pass.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
allocate_slab() currently re-enables irqs before calling to the page allocator.
It depends on gfpflags_allow_blocking() to determine if it's safe to do so.
Now we can instead simply restore irq before calling it through new_slab().
The other caller early_kmem_cache_node_alloc() is unaffected by this.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Continue reducing the irq disabled scope. Check for per-cpu partial slabs with
first with irqs enabled and then recheck with irqs disabled before grabbing
the slab page. Mostly preparatory for the following patches.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
As another step of shortening irq disabled sections in ___slab_alloc(), delay
disabling irqs until we pass the initial checks if there is a cached percpu
slab and it's suitable for our allocation.
Now we have to recheck c->page after actually disabling irqs as an allocation
in irq handler might have replaced it.
Because we call pfmemalloc_match() as one of the checks, we might hit
VM_BUG_ON_PAGE(!PageSlab(page)) in PageSlabPfmemalloc in case we get
interrupted and the page is freed. Thus introduce a pfmemalloc_match_unsafe()
variant that lacks the PageSlab check.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Currently __slab_alloc() disables irqs around the whole ___slab_alloc(). This
includes cases where this is not needed, such as when the allocation ends up in
the page allocator and has to awkwardly enable irqs back based on gfp flags.
Also the whole kmem_cache_alloc_bulk() is executed with irqs disabled even when
it hits the __slab_alloc() slow path, and long periods with disabled interrupts
are undesirable.
As a first step towards reducing irq disabled periods, move irq handling into
___slab_alloc(). Callers will instead prevent the s->cpu_slab percpu pointer
from becoming invalid via get_cpu_ptr(), thus preempt_disable(). This does not
protect against modification by an irq handler, which is still done by disabled
irq for most of ___slab_alloc(). As a small immediate benefit,
slab_out_of_memory() from ___slab_alloc() is now called with irqs enabled.
kmem_cache_alloc_bulk() disables irqs for its fastpath and then re-enables them
before calling ___slab_alloc(), which then disables them at its discretion. The
whole kmem_cache_alloc_bulk() operation also disables preemption.
When ___slab_alloc() calls new_slab() to allocate a new page, re-enable
preemption, because new_slab() will re-enable interrupts in contexts that allow
blocking (this will be improved by later patches).
The patch itself will thus increase overhead a bit due to disabled preemption
(on configs where it matters) and increased disabling/enabling irqs in
kmem_cache_alloc_bulk(), but that will be gradually improved in the following
patches.
Note in __slab_alloc() we need to change the #ifdef CONFIG_PREEMPT guard to
CONFIG_PREEMPT_COUNT to make sure preempt disable/enable is properly paired in
all configurations. On configs without involuntary preemption and debugging
the re-read of kmem_cache_cpu pointer is still compiled out as it was before.
[ Mike Galbraith <efault@gmx.de>: Fix kmem_cache_alloc_bulk() error path ]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
In slab_alloc_node() and do_slab_free() fastpaths we need to guarantee that
our kmem_cache_cpu pointer is from the same cpu as the tid value. Currently
that's done by reading the tid first using this_cpu_read(), then the
kmem_cache_cpu pointer and verifying we read the same tid using the pointer and
plain READ_ONCE().
This can be simplified to just fetching kmem_cache_cpu pointer and then reading
tid using the pointer. That guarantees they are from the same cpu. We don't
need to read the tid using this_cpu_read() because the value will be validated
by this_cpu_cmpxchg_double(), making sure we are on the correct cpu and the
freelist didn't change by anyone preempting us since reading the tid.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
When we allocate slab object from a newly acquired page (from node's partial
list or page allocator), we usually also retain the page as a new percpu slab.
There are two exceptions - when pfmemalloc status of the page doesn't match our
gfp flags, or when the cache has debugging enabled.
The current code for these decisions is not easy to follow, so restructure it
and add comments. The new structure will also help with the following changes.
No functional change.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
The function get_partial() finds a suitable page on a partial list, acquires
and returns its freelist and assigns the page pointer to kmem_cache_cpu.
In later patch we will need more control over the kmem_cache_cpu.page
assignment, so instead of passing a kmem_cache_cpu pointer, pass a pointer to a
pointer to a page that get_partial() can fill and the caller can assign the
kmem_cache_cpu.page pointer. No functional change as all of this still happens
with disabled IRQs.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
The later patches will need more fine grained control over individual actions
in ___slab_alloc(), the only caller of new_slab_objects(), so dissolve it
there. This is a preparatory step with no functional change.
The only minor change is moving WARN_ON_ONCE() for using a constructor together
with __GFP_ZERO to new_slab(), which makes it somewhat less frequent, but still
able to catch a development change introducing a systematic misuse.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
The later patches will need more fine grained control over individual actions
in ___slab_alloc(), the only caller of new_slab_objects(), so this is a first
preparatory step with no functional change.
This adds a goto label that appears unnecessary at this point, but will be
useful for later changes.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Christoph Lameter <cl@linux.com>
Commit d6e0b7fa11 ("slub: make dead caches discard free slabs immediately")
introduced cpu partial flushing for kmemcg caches, based on setting the target
cpu_partial to 0 and adding a flushing check in put_cpu_partial().
This code that sets cpu_partial to 0 was later moved by c9fc586403 ("slab:
introduce __kmemcg_cache_deactivate()") and ultimately removed by 9855609bde
("mm: memcg/slab: use a single set of kmem_caches for all accounted
allocations"). However the check and flush in put_cpu_partial() was never
removed, although it's effectively a dead code. So this patch removes it.
Note that d6e0b7fa11 also added preempt_disable()/enable() to
unfreeze_partials() which could be thus also considered unnecessary. But
further patches will rely on it, so keep it.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
In slab_free_hook() we disable irqs around the debug_check_no_locks_freed()
call, which is unnecessary, as irqs are already being disabled inside the call.
This seems to be leftover from the past where there were more calls inside the
irq disabled sections. Remove the irq disable/enable operations.
Mel noted:
> Looks like it was needed for kmemcheck which went away back in 4.15
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
validate_slab_cache() is called either to handle a sysfs write, or from a
self-test context. In both situations it's straightforward to preallocate a
private object bitmap instead of grabbing the shared static one meant for
critical sections, so let's do that.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Slub has a static spinlock protected bitmap for marking which objects are on
freelist when it wants to list them, for situations where dynamically
allocating such map can lead to recursion or locking issues, and on-stack
bitmap would be too large.
The handlers of debugfs files alloc_traces and free_traces also currently use this
shared bitmap, but their syscall context makes it straightforward to allocate a
private map before entering locked sections, so switch these processing paths
to use a private bitmap.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
slab_debug_trace_open() can only be called on caches with SLAB_STORE_USER flag
and as with all slub debugging flags, such caches avoid cpu or percpu partial
slabs altogether, so there's nothing to flush.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Christoph Lameter <cl@linux.com>
Vijayanand Jitta reports:
Consider the scenario where CONFIG_SLUB_DEBUG_ON is set and we would
want to disable slub_debug for few slabs. Using boot parameter with
slub_debug=-,slab_name syntax doesn't work as expected i.e; only
disabling debugging for the specified list of slabs. Instead it
disables debugging for all slabs, which is wrong.
This patch fixes it by delaying the moment when the global slub_debug
flags variable is updated. In case a "slub_debug=-,slab_name" has been
passed, the global flags remain as initialized (depending on
CONFIG_SLUB_DEBUG_ON enabled or disabled) and are not simply reset to 0.
Link: https://lkml.kernel.org/r/8a3d992a-473a-467b-28a0-4ad2ff60ab82@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Vijayanand Jitta <vjitta@codeaurora.org>
Reviewed-by: Vijayanand Jitta <vjitta@codeaurora.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>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The unit test kmalloc_pagealloc_invalid_free makes sure that for the
higher order slub allocation which goes to page allocator, the free is
called with the correct address i.e. the virtual address of the head
page.
Commit f227f0faf6 ("slub: fix unreclaimable slab stat for bulk free")
unified the free code paths for page allocator based slub allocations
but instead of using the address passed by the caller, it extracted the
address from the page. Thus making the unit test
kmalloc_pagealloc_invalid_free moot. So, fix this by using the address
passed by the caller.
Should we fix this? I think yes because dev expect kasan to catch these
type of programming bugs.
Link: https://lkml.kernel.org/r/20210802180819.1110165-1-shakeelb@google.com
Fixes: f227f0faf6 ("slub: fix unreclaimable slab stat for bulk free")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.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: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The address still includes the tags when it is printed. With hardware
tag-based kasan enabled, we will get a false positive KASAN issue when
we access metadata.
Reset the tag before we access the metadata.
Link: https://lkml.kernel.org/r/20210804090957.12393-3-Kuan-Ying.Lee@mediatek.com
Fixes: aa1ef4d7b3 ("kasan, mm: reset tags when accessing metadata")
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Nicholas Tang <nicholas.tang@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SLUB uses page allocator for higher order allocations and update
unreclaimable slab stat for such allocations. At the moment, the bulk
free for SLUB does not share code with normal free code path for these
type of allocations and have missed the stat update. So, fix the stat
update by common code. The user visible impact of the bug is the
potential of inconsistent unreclaimable slab stat visible through
meminfo and vmstat.
Link: https://lkml.kernel.org/r/20210728155354.3440560-1-shakeelb@google.com
Fixes: 6a486c0ad4 ("mm, sl[ou]b: improve memory accounting")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.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: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 788691464c.
It's not clear why, but it causes unexplained problems in entirely
unrelated xfs code. The most likely explanation is some slab
corruption, possibly triggered due to CONFIG_SLUB_DEBUG_ON. See [1].
It ends up having a few other problems too, like build errors on
arch/arc, and Geert reporting it using much more memory on m68k [3] (it
probably does so elsewhere too, but it is probably just more noticeable
on m68k).
The architecture issues (both build and memory use) are likely just
because this change effectively force-enabled STACKDEPOT (along with a
very bad default value for the stackdepot hash size). But together with
the xfs issue, this all smells like "this commit was not ready" to me.
Link: https://lore.kernel.org/linux-xfs/YPE3l82acwgI2OiV@infradead.org/ [1]
Link: https://lore.kernel.org/lkml/202107150600.LkGNb4Vb-lkp@intel.com/ [2]
Link: https://lore.kernel.org/lkml/CAMuHMdW=eoVzM1Re5FVoEN87nKfiLmM2+Ah7eNu2KXEhCvbZyA@mail.gmail.com/ [3]
Reported-by: Christoph Hellwig <hch@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the helper to check slub_debug_enabled, so that we can confine the
use of #ifdef outside slub.c as well.
Link: https://lkml.kernel.org/r/20210705103229.8505-2-yee.lee@mediatek.com
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Yee Lee <yee.lee@mediatek.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Cc: Nicholas Tang <nicholas.tang@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Many stack traces are similar so there are many similar arrays.
Stackdepot saves each unique stack only once.
Replace field addrs in struct track with depot_stack_handle_t handle. Use
stackdepot to save stack trace.
The benefits are smaller memory overhead and possibility to aggregate
per-cache statistics in the future using the stackdepot handle instead of
matching stacks manually.
[rdunlap@infradead.org: rename save_stack_trace()]
Link: https://lkml.kernel.org/r/20210513051920.29320-1-rdunlap@infradead.org
[vbabka@suse.cz: fix lockdep splat]
Link: https://lkml.kernel.org/r/20210516195150.26740-1-vbabka@suse.czLink: https://lkml.kernel.org/r/20210414163434.4376-1-glittao@gmail.com
Signed-off-by: Oliver Glitta <glittao@gmail.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
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>
Pull RCU updates from Paul McKenney:
- Bitmap parsing support for "all" as an alias for all bits
- Documentation updates
- Miscellaneous fixes, including some that overlap into mm and lockdep
- kvfree_rcu() updates
- mem_dump_obj() updates, with acks from one of the slab-allocator
maintainers
- RCU NOCB CPU updates, including limited deoffloading
- SRCU updates
- Tasks-RCU updates
- Torture-test updates
* 'core-rcu-2021.07.04' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (78 commits)
tasks-rcu: Make show_rcu_tasks_gp_kthreads() be static inline
rcu-tasks: Make ksoftirqd provide RCU Tasks quiescent states
rcu: Add missing __releases() annotation
rcu: Remove obsolete rcu_read_unlock() deadlock commentary
rcu: Improve comments describing RCU read-side critical sections
rcu: Create an unrcu_pointer() to remove __rcu from a pointer
srcu: Early test SRCU polling start
rcu: Fix various typos in comments
rcu/nocb: Unify timers
rcu/nocb: Prepare for fine-grained deferred wakeup
rcu/nocb: Only cancel nocb timer if not polling
rcu/nocb: Delete bypass_timer upon nocb_gp wakeup
rcu/nocb: Cancel nocb_timer upon nocb_gp wakeup
rcu/nocb: Allow de-offloading rdp leader
rcu/nocb: Directly call __wake_nocb_gp() from bypass timer
rcu: Don't penalize priority boosting when there is nothing to boost
rcu: Point to documentation of ordering guarantees
rcu: Make rcu_gp_cleanup() be noinline for tracing
rcu: Restrict RCU_STRICT_GRACE_PERIOD to at most four CPUs
rcu: Make show_rcu_gp_kthreads() dump rcu_node structures blocking GP
...
When running the kernel with panic_on_taint, the usual slub debug error
messages are not being printed when object corruption happens. That's
because we panic in add_taint(), which is called before printing the
additional information. This is a bit unfortunate as the error messages
are actually very useful, especially before a panic. Let's fix this by
moving add_taint() after the errors are printed on the console.
Link: https://lkml.kernel.org/r/1623860738-146761-1-git-send-email-quic_c_gdjako@quicinc.com
Signed-off-by: Georgi Djakov <quic_c_gdjako@quicinc.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Aaron Tomlin <atomlin@redhat.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>
alloc_calls and free_calls implementation in sysfs have two issues, one is
PAGE_SIZE limitation of sysfs and other is it does not adhere to "one
value per file" rule.
To overcome this issues, move the alloc_calls and free_calls
implementation to debugfs.
Debugfs cache will be created if SLAB_STORE_USER flag is set.
Rename the alloc_calls/free_calls to alloc_traces/free_traces, to be
inline with what it does.
[faiyazm@codeaurora.org: fix the leak of alloc/free traces debugfs interface]
Link: https://lkml.kernel.org/r/1624248060-30286-1-git-send-email-faiyazm@codeaurora.org
Link: https://lkml.kernel.org/r/1623438200-19361-1-git-send-email-faiyazm@codeaurora.org
Signed-off-by: Faiyaz Mohammed <faiyazm@codeaurora.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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>
Obscuring the pointers that slub shows when debugging makes for some
confusing slub debug messages:
Padding overwritten. 0x0000000079f0674a-0x000000000d4dce17
Those addresses are hashed for kernel security reasons. If we're trying
to be secure with slub_debug on the commandline we have some big problems
given that we dump whole chunks of kernel memory to the kernel logs.
Let's force on the no_hash_pointers commandline flag when slub_debug is on
the commandline. This makes slub debug messages more meaningful and if by
chance a kernel address is in some slub debug object dump we will have a
better chance of figuring out what went wrong.
Note that we don't use %px in the slub code because we want to reduce the
number of places that %px is used in the kernel. This also nicely prints
a big fat warning at kernel boot if slub_debug is on the commandline so
that we know that this kernel shouldn't be used on production systems.
[akpm@linux-foundation.org: fix build with CONFIG_SLUB_DEBUG=n]
Link: https://lkml.kernel.org/r/20210601182202.3011020-5-swboyd@chromium.org
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Petr Mladek <pmladek@suse.com>
Cc: Joe Perches <joe@perches.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: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Ideally, slab_fix() would be marked with __printf and the format here
would not use \n as that's emitted by the slab_fix(). Make these changes.
Link: https://lkml.kernel.org/r/20210601182202.3011020-4-swboyd@chromium.org
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The message argument isn't used here. Let's pass the string to the printk
message so that the developer can figure out what's happening, instead of
guessing that a redzone is being restored, etc.
Link: https://lkml.kernel.org/r/20210601182202.3011020-3-swboyd@chromium.org
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joe Perches <joe@perches.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Petch series "slub: Print non-hashed pointers in slub debugging", v3.
I was doing some debugging recently and noticed that my pointers were
being hashed while slub_debug was on the kernel commandline. Let's force
on the no hash pointer option when slub_debug is on the kernel commandline
so that the prints are more meaningful.
The first two patches are something else I noticed while looking at the
code. The message argument is never used so the debugging messages are
not as clear as they could be and the slub_debug=- behavior seems to be
busted. Then there's a printf fixup from Joe and the final patch is the
one that force disables pointer hashing.
This patch (of 4):
Passing slub_debug=- on the kernel commandline is supposed to disable slub
debugging. This is especially useful with CONFIG_SLUB_DEBUG_ON where the
default is to have slub debugging enabled in the build. Due to some code
reorganization this behavior was dropped, but the code to make it work
mostly stuck around. Restore the previous behavior by disabling the
static key when we parse the commandline and see that we're trying to
disable slub debugging.
Link: https://lkml.kernel.org/r/20210601182202.3011020-1-swboyd@chromium.org
Link: https://lkml.kernel.org/r/20210601182202.3011020-2-swboyd@chromium.org
Fixes: ca0cab65ea ("mm, slub: introduce static key for slub_debug()")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joe Perches <joe@perches.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Function resiliency_test() is hidden behind #ifdef SLUB_RESILIENCY_TEST
that is not part of Kconfig, so nobody runs it.
This function is replaced with KUnit test for SLUB added by the previous
patch "selftests: add a KUnit test for SLUB debugging functionality".
Link: https://lkml.kernel.org/r/20210511150734.3492-3-glittao@gmail.com
Signed-off-by: Oliver Glitta <glittao@gmail.com>
Reviewed-by: Marco Elver <elver@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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>
Cc: Oliver Glitta <glittao@gmail.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Daniel Latypov <dlatypov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SLUB has resiliency_test() function which is hidden behind #ifdef
SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody runs it.
KUnit should be a proper replacement for it.
Try changing byte in redzone after allocation and changing pointer to next
free node, first byte, 50th byte and redzone byte. Check if validation
finds errors.
There are several differences from the original resiliency test: Tests
create own caches with known state instead of corrupting shared kmalloc
caches.
The corruption of freepointer uses correct offset, the original resiliency
test got broken with freepointer changes.
Scratch changing random byte test, because it does not have meaning in
this form where we need deterministic results.
Add new option CONFIG_SLUB_KUNIT_TEST in Kconfig. Tests next_pointer,
first_word and clobber_50th_byte do not run with KASAN option on. Because
the test deliberately modifies non-allocated objects.
Use kunit_resource to count errors in cache and silence bug reports.
Count error whenever slab_bug() or slab_fix() is called or when the count
of pages is wrong.
[glittao@gmail.com: remove unused function test_exit(), from SLUB KUnit test]
Link: https://lkml.kernel.org/r/20210512140656.12083-1-glittao@gmail.com
[akpm@linux-foundation.org: export kasan_enable/disable_current to modules]
Link: https://lkml.kernel.org/r/20210511150734.3492-2-glittao@gmail.com
Signed-off-by: Oliver Glitta <glittao@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Daniel Latypov <dlatypov@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes build with CONFIG_SLAB_FREELIST_HARDENED=y.
Hopefully. But it's the right thing to do anwyay.
Fixes: 1ad53d9fa3 ("slub: improve bit diffusion for freelist ptr obfuscation")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=213417
Reported-by: <vannguye@cisco.com>
Acked-by: Kees Cook <keescook@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>
It turns out that SLUB redzoning ("slub_debug=Z") checks from
s->object_size rather than from s->inuse (which is normally bumped to
make room for the freelist pointer), so a cache created with an object
size less than 24 would have the freelist pointer written beyond
s->object_size, causing the redzone to be corrupted by the freelist
pointer. This was very visible with "slub_debug=ZF":
BUG test (Tainted: G B ): Right Redzone overwritten
-----------------------------------------------------------------------------
INFO: 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. First byte 0x1a instead of 0xbb
INFO: Slab 0xffffef3950b47000 objects=170 used=170 fp=0x0000000000000000 flags=0x8000000000000200
INFO: Object 0xffff957ead1c05d8 @offset=1496 fp=0xffff957ead1c0620
Redzone (____ptrval____): bb bb bb bb bb bb bb bb ........
Object (____ptrval____): 00 00 00 00 00 f6 f4 a5 ........
Redzone (____ptrval____): 40 1d e8 1a aa @....
Padding (____ptrval____): 00 00 00 00 00 00 00 00 ........
Adjust the offset to stay within s->object_size.
(Note that no caches of in this size range are known to exist in the
kernel currently.)
Link: https://lkml.kernel.org/r/20210608183955.280836-4-keescook@chromium.org
Link: https://lore.kernel.org/linux-mm/20200807160627.GA1420741@elver.google.com/
Link: https://lore.kernel.org/lkml/0f7dd7b2-7496-5e2d-9488-2ec9f8e90441@suse.cz/Fixes: 89b83f282d (slub: avoid redzone when choosing freepointer location)
Link: https://lore.kernel.org/lkml/CANpmjNOwZ5VpKQn+SYWovTkFB4VsT-RPwyENBmaK0dLcpqStkA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Marco Elver <elver@google.com>
Reported-by: "Lin, Zhenpeng" <zplin@psu.edu>
Tested-by: Marco Elver <elver@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
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>
The redzone area for SLUB exists between s->object_size and s->inuse
(which is at least the word-aligned object_size). If a cache were
created with an object_size smaller than sizeof(void *), the in-object
stored freelist pointer would overwrite the redzone (e.g. with boot
param "slub_debug=ZF"):
BUG test (Tainted: G B ): Right Redzone overwritten
-----------------------------------------------------------------------------
INFO: 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. First byte 0x1a instead of 0xbb
INFO: Slab 0xffffef3950b47000 objects=170 used=170 fp=0x0000000000000000 flags=0x8000000000000200
INFO: Object 0xffff957ead1c05d8 @offset=1496 fp=0xffff957ead1c0620
Redzone (____ptrval____): bb bb bb bb bb bb bb bb ........
Object (____ptrval____): f6 f4 a5 40 1d e8 ...@..
Redzone (____ptrval____): 1a aa ..
Padding (____ptrval____): 00 00 00 00 00 00 00 00 ........
Store the freelist pointer out of line when object_size is smaller than
sizeof(void *) and redzoning is enabled.
Additionally remove the "smaller than sizeof(void *)" check under
CONFIG_DEBUG_VM in kmem_cache_sanity_check() as it is now redundant:
SLAB and SLOB both handle small sizes.
(Note that no caches within this size range are known to exist in the
kernel currently.)
Link: https://lkml.kernel.org/r/20210608183955.280836-3-keescook@chromium.org
Fixes: 81819f0fc8 ("SLUB core")
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Lin, Zhenpeng" <zplin@psu.edu>
Cc: Marco Elver <elver@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
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 "Actually fix freelist pointer vs redzoning", v4.
This fixes redzoning vs the freelist pointer (both for middle-position
and very small caches). Both are "theoretical" fixes, in that I see no
evidence of such small-sized caches actually be used in the kernel, but
that's no reason to let the bugs continue to exist, especially since
people doing local development keep tripping over it. :)
This patch (of 3):
Instead of repeating "Redzone" and "Poison", clarify which sides of
those zones got tripped. Additionally fix column alignment in the
trailer.
Before:
BUG test (Tainted: G B ): Redzone overwritten
...
Redzone (____ptrval____): bb bb bb bb bb bb bb bb ........
Object (____ptrval____): f6 f4 a5 40 1d e8 ...@..
Redzone (____ptrval____): 1a aa ..
Padding (____ptrval____): 00 00 00 00 00 00 00 00 ........
After:
BUG test (Tainted: G B ): Right Redzone overwritten
...
Redzone (____ptrval____): bb bb bb bb bb bb bb bb ........
Object (____ptrval____): f6 f4 a5 40 1d e8 ...@..
Redzone (____ptrval____): 1a aa ..
Padding (____ptrval____): 00 00 00 00 00 00 00 00 ........
The earlier commits that slowly resulted in the "Before" reporting were:
d86bd1bece ("mm/slub: support left redzone")
ffc79d2880 ("slub: use print_hex_dump")
2492268472 ("SLUB: change error reporting format to follow lockdep loosely")
Link: https://lkml.kernel.org/r/20210608183955.280836-1-keescook@chromium.org
Link: https://lkml.kernel.org/r/20210608183955.280836-2-keescook@chromium.org
Link: https://lore.kernel.org/lkml/cfdb11d7-fb8e-e578-c939-f7f5fb69a6bd@suse.cz/
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Marco Elver <elver@google.com>
Cc: "Lin, Zhenpeng" <zplin@psu.edu>
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: 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>
With CONFIG_DEBUG_PAGEALLOC enabled, the kernel should also untag the
object pointer, as done in get_freepointer().
Failing to do so reportedly leads to SLUB freelist corruptions that
manifest as boot-time crashes.
Link: https://lkml.kernel.org/r/20210514072228.534418-1-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Elliot Berman <eberman@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Paul E. McKenney reported [1] that commit 1f0723a4c0 ("mm, slub: enable
slub_debug static key when creating cache with explicit debug flags")
results in the lockdep complaint:
======================================================
WARNING: possible circular locking dependency detected
5.12.0+ #15 Not tainted
------------------------------------------------------
rcu_torture_sta/109 is trying to acquire lock:
ffffffff96063cd0 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_enable+0x9/0x20
but task is already holding lock:
ffffffff96173c28 (slab_mutex){+.+.}-{3:3}, at: kmem_cache_create_usercopy+0x2d/0x250
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (slab_mutex){+.+.}-{3:3}:
lock_acquire+0xb9/0x3a0
__mutex_lock+0x8d/0x920
slub_cpu_dead+0x15/0xf0
cpuhp_invoke_callback+0x17a/0x7c0
cpuhp_invoke_callback_range+0x3b/0x80
_cpu_down+0xdf/0x2a0
cpu_down+0x2c/0x50
device_offline+0x82/0xb0
remove_cpu+0x1a/0x30
torture_offline+0x80/0x140
torture_onoff+0x147/0x260
kthread+0x10a/0x140
ret_from_fork+0x22/0x30
-> #0 (cpu_hotplug_lock){++++}-{0:0}:
check_prev_add+0x8f/0xbf0
__lock_acquire+0x13f0/0x1d80
lock_acquire+0xb9/0x3a0
cpus_read_lock+0x21/0xa0
static_key_enable+0x9/0x20
__kmem_cache_create+0x38d/0x430
kmem_cache_create_usercopy+0x146/0x250
kmem_cache_create+0xd/0x10
rcu_torture_stats+0x79/0x280
kthread+0x10a/0x140
ret_from_fork+0x22/0x30
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(slab_mutex);
lock(cpu_hotplug_lock);
lock(slab_mutex);
lock(cpu_hotplug_lock);
*** DEADLOCK ***
1 lock held by rcu_torture_sta/109:
#0: ffffffff96173c28 (slab_mutex){+.+.}-{3:3}, at: kmem_cache_create_usercopy+0x2d/0x250
stack backtrace:
CPU: 3 PID: 109 Comm: rcu_torture_sta Not tainted 5.12.0+ #15
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
dump_stack+0x6d/0x89
check_noncircular+0xfe/0x110
? lock_is_held_type+0x98/0x110
check_prev_add+0x8f/0xbf0
__lock_acquire+0x13f0/0x1d80
lock_acquire+0xb9/0x3a0
? static_key_enable+0x9/0x20
? mark_held_locks+0x49/0x70
cpus_read_lock+0x21/0xa0
? static_key_enable+0x9/0x20
static_key_enable+0x9/0x20
__kmem_cache_create+0x38d/0x430
kmem_cache_create_usercopy+0x146/0x250
? rcu_torture_stats_print+0xd0/0xd0
kmem_cache_create+0xd/0x10
rcu_torture_stats+0x79/0x280
? rcu_torture_stats_print+0xd0/0xd0
kthread+0x10a/0x140
? kthread_park+0x80/0x80
ret_from_fork+0x22/0x30
This is because there's one order of locking from the hotplug callbacks:
lock(cpu_hotplug_lock); // from hotplug machinery itself
lock(slab_mutex); // in e.g. slab_mem_going_offline_callback()
And commit 1f0723a4c0 made the reverse sequence possible:
lock(slab_mutex); // in kmem_cache_create_usercopy()
lock(cpu_hotplug_lock); // kmem_cache_open() -> static_key_enable()
The simplest fix is to move static_key_enable() to a place before slab_mutex is
taken. That means kmem_cache_create_usercopy() in mm/slab_common.c which is not
ideal for SLUB-specific code, but the #ifdef CONFIG_SLUB_DEBUG makes it
at least self-contained and obvious.
[1] https://lore.kernel.org/lkml/20210502171827.GA3670492@paulmck-ThinkPad-P17-Gen-1/
Link: https://lkml.kernel.org/r/20210504120019.26791-1-vbabka@suse.cz
Fixes: 1f0723a4c0 ("mm, slub: enable slub_debug static key when creating cache with explicit debug flags")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Paul E. McKenney <paulmck@kernel.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>
This change uses the previously added memory initialization feature of
HW_TAGS KASAN routines for slab memory when init_on_free is enabled.
With this change, memory initialization memset() is no longer called when
both HW_TAGS KASAN and init_on_free are enabled. Instead, memory is
initialized in KASAN runtime.
For SLUB, the memory initialization memset() is moved into
slab_free_hook() that currently directly follows the initialization loop.
A new argument is added to slab_free_hook() that indicates whether to
initialize the memory or not.
To avoid discrepancies with which memory gets initialized that can be
caused by future changes, both KASAN hook and initialization memset() are
put together and a warning comment is added.
Combining setting allocation tags with memory initialization improves
HW_TAGS KASAN performance when init_on_free is enabled.
Link: https://lkml.kernel.org/r/190fd15c1886654afdec0d19ebebd5ade665b601.1615296150.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.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: Evgenii Stepanov <eugenis@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
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 change uses the previously added memory initialization feature of
HW_TAGS KASAN routines for slab memory when init_on_alloc is enabled.
With this change, memory initialization memset() is no longer called when
both HW_TAGS KASAN and init_on_alloc are enabled. Instead, memory is
initialized in KASAN runtime.
The memory initialization memset() is moved into slab_post_alloc_hook()
that currently directly follows the initialization loop. A new argument
is added to slab_post_alloc_hook() that indicates whether to initialize
the memory or not.
To avoid discrepancies with which memory gets initialized that can be
caused by future changes, both KASAN hook and initialization memset() are
put together and a warning comment is added.
Combining setting allocation tags with memory initialization improves
HW_TAGS KASAN performance when init_on_alloc is enabled.
Link: https://lkml.kernel.org/r/c1292aeb5d519da221ec74a0684a949b027d7720.1615296150.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.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: Evgenii Stepanov <eugenis@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
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>
Commit ca0cab65ea ("mm, slub: introduce static key for slub_debug()")
introduced a static key to optimize the case where no debugging is
enabled for any cache. The static key is enabled when slub_debug boot
parameter is passed, or CONFIG_SLUB_DEBUG_ON enabled.
However, some caches might be created with one or more debugging flags
explicitly passed to kmem_cache_create(), and the commit missed this.
Thus the debugging functionality would not be actually performed for
these caches unless the static key gets enabled by boot param or config.
This patch fixes it by checking for debugging flags passed to
kmem_cache_create() and enabling the static key accordingly.
Note such explicit debugging flags should not be used outside of
debugging and testing as they will now enable the static key globally.
btrfs_init_cachep() creates a cache with SLAB_RED_ZONE but that's a
mistake that's being corrected [1]. rcu_torture_stats() creates a cache
with SLAB_STORE_USER, but that is a testing module so it's OK and will
start working as intended after this patch.
Also note that in case of backports to kernels before v5.12 that don't
have 59450bbc12 ("mm, slab, slub: stop taking cpu hotplug lock"),
static_branch_enable_cpuslocked() should be used.
[1] https://lore.kernel.org/linux-btrfs/20210315141824.26099-1-dsterba@suse.com/
Link: https://lkml.kernel.org/r/20210315153415.24404-1-vbabka@suse.cz
Fixes: ca0cab65ea ("mm, slub: introduce static key for slub_debug()")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Oliver Glitta <glittao@gmail.com>
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>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Bitmap support for "N" as alias for last bit
- kvfree_rcu updates
- mm_dump_obj() updates. (One of these is to mm, but was suggested by Andrew Morton.)
- RCU callback offloading update
- Polling RCU grace-period interfaces
- Realtime-related RCU updates
- Tasks-RCU updates
- Torture-test updates
- Torture-test scripting updates
- Miscellaneous fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'core-rcu-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:
- Support for "N" as alias for last bit in bitmap parsing library (eg
using syntax like "nohz_full=2-N")
- kvfree_rcu updates
- mm_dump_obj() updates. (One of these is to mm, but was suggested by
Andrew Morton.)
- RCU callback offloading update
- Polling RCU grace-period interfaces
- Realtime-related RCU updates
- Tasks-RCU updates
- Torture-test updates
- Torture-test scripting updates
- Miscellaneous fixes
* tag 'core-rcu-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits)
rcutorture: Test start_poll_synchronize_rcu() and poll_state_synchronize_rcu()
rcu: Provide polling interfaces for Tiny RCU grace periods
torture: Fix kvm.sh --datestamp regex check
torture: Consolidate qemu-cmd duration editing into kvm-transform.sh
torture: Print proper vmlinux path for kvm-again.sh runs
torture: Make TORTURE_TRUST_MAKE available in kvm-again.sh environment
torture: Make kvm-transform.sh update jitter commands
torture: Add --duration argument to kvm-again.sh
torture: Add kvm-again.sh to rerun a previous torture-test
torture: Create a "batches" file for build reuse
torture: De-capitalize TORTURE_SUITE
torture: Make upper-case-only no-dot no-slash scenario names official
torture: Rename SRCU-t and SRCU-u to avoid lowercase characters
torture: Remove no-mpstat error message
torture: Record kvm-test-1-run.sh and kvm-test-1-run-qemu.sh PIDs
torture: Record jitter start/stop commands
torture: Extract kvm-test-1-run-qemu.sh from kvm-test-1-run.sh
torture: Record TORTURE_KCONFIG_GDB_ARG in qemu-cmd
torture: Abstract jitter.sh start/stop into scripts
rcu: Provide polling interfaces for Tree RCU grace periods
...
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Merge tag 'printk-for-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk updates from Petr Mladek:
- Stop synchronizing kernel log buffer readers by logbuf_lock. As a
result, the access to the buffer is fully lockless now.
Note that printk() itself still uses locks because it tries to flush
the messages to the console immediately. Also the per-CPU temporary
buffers are still there because they prevent infinite recursion and
serialize backtraces from NMI. All this is going to change in the
future.
- kmsg_dump API rework and cleanup as a side effect of the logbuf_lock
removal.
- Make bstr_printf() aware that %pf and %pF formats could deference the
given pointer.
- Show also page flags by %pGp format.
- Clarify the documentation for plain pointer printing.
- Do not show no_hash_pointers warning multiple times.
- Update Senozhatsky email address.
- Some clean up.
* tag 'printk-for-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: (24 commits)
lib/vsprintf.c: remove leftover 'f' and 'F' cases from bstr_printf()
printk: clarify the documentation for plain pointer printing
kernel/printk.c: Fixed mundane typos
printk: rename vprintk_func to vprintk
vsprintf: dump full information of page flags in pGp
mm, slub: don't combine pr_err with INFO
mm, slub: use pGp to print page flags
MAINTAINERS: update Senozhatsky email address
lib/vsprintf: do not show no_hash_pointers message multiple times
printk: console: remove unnecessary safe buffer usage
printk: kmsg_dump: remove _nolock() variants
printk: remove logbuf_lock
printk: introduce a kmsg_dump iterator
printk: kmsg_dumper: remove @active field
printk: add syslog_lock
printk: use atomic64_t for devkmsg_user.seq
printk: use seqcount_latch for clear_seq
printk: introduce CONSOLE_LOG_MAX
printk: consolidate kmsg_dump_get_buffer/syslog_print_all code
printk: refactor kmsg_dump_get_buffer()
...
Pull RCU changes from Paul E. McKenney:
- Bitmap support for "N" as alias for last bit
- kvfree_rcu updates
- mm_dump_obj() updates. (One of these is to mm, but was suggested by Andrew Morton.)
- RCU callback offloading update
- Polling RCU grace-period interfaces
- Realtime-related RCU updates
- Tasks-RCU updates
- Torture-test updates
- Torture-test scripting updates
- Miscellaneous fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It is strange to combine "pr_err" with "INFO", so let's remove the
prefix completely.
This patch is motivated by David's comment[1].
- before the patch
[ 8846.517809] INFO: Slab 0x00000000f42a2c60 objects=33 used=3 fp=0x0000000060d32ca8 flags=0x17ffffc0010200(slab|head)
- after the patch
[ 6343.396602] Slab 0x000000004382e02b objects=33 used=3 fp=0x000000009ae06ffc flags=0x17ffffc0010200(slab|head)
[1] https://lore.kernel.org/linux-mm/b9c0f2b6-e9b0-0c36-ebdd-2bc684c5a762@redhat.com/#t
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210319101246.73513-3-laoar.shao@gmail.com
As pGp has been already introduced in printk, we'd better use it to make
the output human readable.
Before this change, the output is,
[ 6155.716018] INFO: Slab 0x000000004027dd4f objects=33 used=3 fp=0x000000008cd1579c flags=0x17ffffc0010200
While after this change, the output is,
[ 8846.517809] INFO: Slab 0x00000000f42a2c60 objects=33 used=3 fp=0x0000000060d32ca8 flags=0x17ffffc0010200(slab|head)
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210319101246.73513-2-laoar.shao@gmail.com
This reverts commit 8ff60eb052.
The kernel test robot reports a huge performance regression due to the
commit, and the reason seems fairly straightforward: when there is
contention on the page list (which is what causes acquire_slab() to
fail), we do _not_ want to just loop and try again, because that will
transfer the contention to the 'n->list_lock' spinlock we hold, and
just make things even worse.
This is admittedly likely a problem only on big machines - the kernel
test robot report comes from a 96-thread dual socket Intel Xeon Gold
6252 setup, but the regression there really is quite noticeable:
-47.9% regression of stress-ng.rawpkt.ops_per_sec
and the commit that was marked as being fixed (7ced371971: "slub:
Acquire_slab() avoid loop") actually did the loop exit early very
intentionally (the hint being that "avoid loop" part of that commit
message), exactly to avoid this issue.
The correct thing to do may be to pick some kind of reasonable middle
ground: instead of breaking out of the loop on the very first sign of
contention, or trying over and over and over again, the right thing may
be to re-try _once_, and then give up on the second failure (or pick
your favorite value for "once"..).
Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/lkml/20210301080404.GF12822@xsang-OptiPlex-9020/
Cc: Jann Horn <jannh@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The mem_dump_obj() functionality adds a few hundred bytes, which is a
small price to pay. Except on kernels built with CONFIG_PRINTK=n, in
which mem_dump_obj() messages will be suppressed. This commit therefore
makes mem_dump_obj() be a static inline empty function on kernels built
with CONFIG_PRINTK=n and excludes all of its support functions as well.
This avoids kernel bloat on systems that cannot use mem_dump_obj().
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: <linux-mm@kvack.org>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
For allocations from kmalloc caches, kasan_kmalloc() always follows
kasan_slab_alloc(). Currenly, both of them unpoison the whole object,
which is unnecessary.
This patch provides separate implementations for both annotations:
kasan_slab_alloc() unpoisons the whole object, and kasan_kmalloc() only
poisons the redzone.
For generic KASAN, the redzone start might not be aligned to
KASAN_GRANULE_SIZE. Therefore, the poisoning is split in two parts:
kasan_poison_last_granule() poisons the unaligned part, and then
kasan_poison() poisons the rest.
This patch also clarifies alignment guarantees of each of the poisoning
functions and drops the unnecessary round_up() call for redzone_end.
With this change, the early SLUB cache annotation needs to be changed to
kasan_slab_alloc(), as kasan_kmalloc() doesn't unpoison objects now. The
number of poisoned bytes for objects in this cache stays the same, as
kmem_cache_node->object_size is equal to sizeof(struct kmem_cache_node).
Link: https://lkml.kernel.org/r/7e3961cb52be380bc412860332063f5f7ce10d13.1612546384.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Peter Collingbourne <pcc@google.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>
Inserts KFENCE hooks into the SLUB allocator.
To pass the originally requested size to KFENCE, add an argument
'orig_size' to slab_alloc*(). The additional argument is required to
preserve the requested original size for kmalloc() allocations, which
uses size classes (e.g. an allocation of 272 bytes will return an object
of size 512). Therefore, kmem_cache::size does not represent the
kmalloc-caller's requested size, and we must introduce the argument
'orig_size' to propagate the originally requested size to KFENCE.
Without the originally requested size, we would not be able to detect
out-of-bounds accesses for objects placed at the end of a KFENCE object
page if that object is not equal to the kmalloc-size class it was
bucketed into.
When KFENCE is disabled, there is no additional overhead, since
slab_alloc*() functions are __always_inline.
Link: https://lkml.kernel.org/r/20201103175841.3495947-6-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Jann Horn <jannh@google.com>
Co-developed-by: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joern Engel <joern@purestorage.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: SeongJae Park <sjpark@amazon.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Generic mm functions that call KASAN annotations that might report a bug
pass _RET_IP_ to them as an argument. This allows KASAN to include the
name of the function that called the mm function in its report's header.
Now that KASAN has inline wrappers for all of its annotations, move
_RET_IP_ to those wrappers to simplify annotation call sites.
Link: https://linux-review.googlesource.com/id/I8fb3c06d49671305ee184175a39591bc26647a67
Link: https://lkml.kernel.org/r/5c1490eddf20b436b8c4eeea83fce47687d5e4a4.1610733117.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Peter Collingbourne <pcc@google.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>
SLUB currently account kmalloc() and kmalloc_node() allocations larger
than order-1 page per-node. But it forget to update the per-memcg
vmstats. So it can lead to inaccurate statistics of "slab_unreclaimable"
which is from memory.stat. Fix it by using mod_lruvec_page_state instead
of mod_node_page_state.
Link: https://lkml.kernel.org/r/20210223092423.42420-1-songmuchun@bytedance.com
Fixes: 6a486c0ad4 ("mm, sl[ou]b: improve memory accounting")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
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>
In general it's unknown in advance if a slab page will contain accounted
objects or not. In order to avoid memory waste, an obj_cgroup vector is
allocated dynamically when a need to account of a new object arises. Such
approach is memory efficient, but requires an expensive cmpxchg() to set
up the memcg/objcgs pointer, because an allocation can race with a
different allocation on another cpu.
But in some common cases it's known for sure that a slab page will contain
accounted objects: if the page belongs to a slab cache with a SLAB_ACCOUNT
flag set. It includes such popular objects like vm_area_struct, anon_vma,
task_struct, etc.
In such cases we can pre-allocate the objcgs vector and simple assign it
to the page without any atomic operations, because at this early stage the
page is not visible to anyone else.
A very simplistic benchmark (allocating 10000000 64-bytes objects in a
row) shows ~15% win. In the real life it seems that most workloads are
not very sensitive to the speed of (accounted) slab allocations.
[guro@fb.com: open-code set_page_objcgs() and add some comments, by Johannes]
Link: https://lkml.kernel.org/r/20201113001926.GA2934489@carbon.dhcp.thefacebook.com
[akpm@linux-foundation.org: fix it for mm-slub-call-account_slab_page-after-slab-page-initialization-fix.patch]
Link: https://lkml.kernel.org/r/20201110195753.530157-2-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The boot param and config determine the value of memcg_sysfs_enabled,
which is unused since commit 10befea91b ("mm: memcg/slab: use a single
set of kmem_caches for all allocations") as there are no per-memcg kmem
caches anymore.
Link: https://lkml.kernel.org/r/20210127124745.7928-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.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>
In deactivate_slab() we currently move all but one objects on the cpu
freelist to the page freelist one by one using the costly cmpxchg_double()
operation. Then we unfreeze the page while moving the last object on page
freelist, with a final cmpxchg_double().
This can be optimized to avoid the cmpxchg_double() per object. Just
count the objects on cpu freelist (to adjust page->inuse properly) and
also remember the last object in the chain. Then splice page->freelist to
the last object and effectively add the whole cpu freelist to
page->freelist while unfreezing the page, with a single cmpxchg_double().
Link: https://lkml.kernel.org/r/20210115183543.15097-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Jann Horn <jannh@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>
Since commit 03afc0e25f ("slab: get_online_mems for
kmem_cache_{create,destroy,shrink}") we are taking memory hotplug lock for
SLAB and SLUB when creating, destroying or shrinking a cache. It is quite
a heavy lock and it's best to avoid it if possible, as we had several
issues with lockdep complaining about ordering in the past, see e.g.
e4f8e513c3 ("mm/slub: fix a deadlock in show_slab_objects()").
The problem scenario in 03afc0e25f (solved by the memory hotplug lock)
can be summarized as follows: while there's slab_mutex synchronizing new
kmem cache creation and SLUB's MEM_GOING_ONLINE callback
slab_mem_going_online_callback(), we may miss creation of kmem_cache_node
for the hotplugged node in the new kmem cache, because the hotplug
callback doesn't yet see the new cache, and cache creation in
init_kmem_cache_nodes() only inits kmem_cache_node for nodes in the
N_NORMAL_MEMORY nodemask, which however may not yet include the new node,
as that happens only later after the MEM_GOING_ONLINE callback.
Instead of using get/put_online_mems(), the problem can be solved by SLUB
maintaining its own nodemask of nodes for which it has allocated the
per-node kmem_cache_node structures. This nodemask would generally mirror
the N_NORMAL_MEMORY nodemask, but would be updated only in under SLUB's
control in its memory hotplug callbacks under the slab_mutex. This patch
adds such nodemask and its handling.
Commit 03afc0e25f mentiones "issues like [the one above]", but there
don't appear to be further issues. All the paths (shared for SLAB and
SLUB) taking the memory hotplug locks are also taking the slab_mutex,
except kmem_cache_shrink() where 03afc0e25f replaced slab_mutex with
get/put_online_mems().
We however cannot simply restore slab_mutex in kmem_cache_shrink(), as
SLUB can enters the function from a write to sysfs 'shrink' file, thus
holding kernfs lock, and in kmem_cache_create() the kernfs lock is nested
within slab_mutex. But on closer inspection we don't actually need to
protect kmem_cache_shrink() from hotplug callbacks: While SLUB's
__kmem_cache_shrink() does for_each_kmem_cache_node(), missing a new node
added in parallel hotplug is not fatal, and parallel hotremove does not
free kmem_cache_node's anymore after the previous patch, so use-after free
cannot happen. The per-node shrinking itself is protected by
n->list_lock. Same is true for SLAB, and SLOB is no-op.
SLAB also doesn't need the memory hotplug locking, which it only gained by
03afc0e25f through the shared paths in slab_common.c. Its memory
hotplug callbacks are also protected by slab_mutex against races with
these paths. The problem of SLUB relying on N_NORMAL_MEMORY doesn't apply
to SLAB, as its setup_kmem_cache_nodes relies on N_ONLINE, and the new
node is already set there during the MEM_GOING_ONLINE callback, so no
special care is needed for SLAB.
As such, this patch removes all get/put_online_mems() usage by the slab
subsystem.
Link: https://lkml.kernel.org/r/20210113131634.3671-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Qian Cai <cai@redhat.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>
Patch series "mm, slab, slub: remove cpu and memory hotplug locks".
Some related work caused me to look at how we use get/put_mems_online()
and get/put_online_cpus() during kmem cache
creation/descruction/shrinking, and realize that it should be actually
safe to remove all of that with rather small effort (as e.g. Michal Hocko
suspected in some of the past discussions already). This has the benefit
to avoid rather heavy locks that have caused locking order issues already
in the past. So this is the result, Patches 2 and 3 remove memory hotplug
and cpu hotplug locking, respectively. Patch 1 is due to realization that
in fact some races exist despite the locks (even if not removed), but the
most sane solution is not to introduce more of them, but rather accept
some wasted memory in scenarios that should be rare anyway (full memory
hot remove), as we do the same in other contexts already.
This patch (of 3):
Commit e4f8e513c3 ("mm/slub: fix a deadlock in show_slab_objects()") has
fixed a problematic locking order by removing the memory hotplug lock
get/put_online_mems() from show_slab_objects(). During the discussion, it
was argued [1] that this is OK, because existing slabs on the node would
prevent a hotremove to proceed.
That's true, but per-node kmem_cache_node structures are not necessarily
allocated on the same node and may exist even without actual slab pages on
the same node. Any path that uses get_node() directly or via
for_each_kmem_cache_node() (such as show_slab_objects()) can race with
freeing of kmem_cache_node even with the !NULL check, resulting in
use-after-free.
To that end, commit e4f8e513c3 argues in a comment that:
* We don't really need mem_hotplug_lock (to hold off
* slab_mem_going_offline_callback) here because slab's memory hot
* unplug code doesn't destroy the kmem_cache->node[] data.
While it's true that slab_mem_going_offline_callback() doesn't free the
kmem_cache_node, the later callback slab_mem_offline_callback() actually
does, so the race and use-after-free exists. Not just for
show_slab_objects() after commit e4f8e513c3, but also many other places
that are not under slab_mutex. And adding slab_mutex locking or other
synchronization to SLUB paths such as get_any_partial() would be bad for
performance and error-prone.
The easiest solution is therefore to make the abovementioned comment true
and stop freeing the kmem_cache_node structures, accepting some wasted
memory in the full memory node removal scenario. Analogically we also
don't free hotremoved pgdat as mentioned in [1], nor the similar per-node
structures in SLAB. Importantly this approach will not block the
hotremove, as generally such nodes should be movable in order to succeed
hotremove in the first place, and thus the GFP_KERNEL allocated
kmem_cache_node will come from elsewhere.
[1] https://lore.kernel.org/linux-mm/20190924151147.GB23050@dhcp22.suse.cz/
Link: https://lkml.kernel.org/r/20210113131634.3671-1-vbabka@suse.cz
Link: https://lkml.kernel.org/r/20210113131634.3671-2-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: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Qian Cai <cai@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If kmemleak is enabled, it uses a kmem cache for its own objects. These
objects are used to hold information kmemleak uses, including a stack
trace. If slub_debug is also turned on, each of them has *another* stack
trace, so the overhead adds up, and on my tests (on ARCH=um, admittedly)
2/3rds of the allocations end up being doing the stack tracing.
Turn off SLAB_STORE_USER if SLAB_NOLEAKTRACE was given, to avoid storing
the essentially same data twice.
Link: https://lkml.kernel.org/r/20210113215114.d94efa13ba30.I117b6764e725b3192318bbcf4269b13b709539ae@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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>
This argument hasn't been used since e153362a50 ("slub: Remove objsize
check in kmem_cache_flags()") so simply remove it.
Link: https://lkml.kernel.org/r/20210126095733.974665-1-nborisov@suse.com
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, a trace record generated by the RCU core is as below.
... kmem_cache_free: call_site=rcu_core+0x1fd/0x610 ptr=00000000f3b49a66
It doesn't tell us what the RCU core has freed.
This patch adds the slab name to trace_kmem_cache_free().
The new format is as follows.
... kmem_cache_free: call_site=rcu_core+0x1fd/0x610 ptr=0000000037f79c8d name=dentry
... kmem_cache_free: call_site=rcu_core+0x1fd/0x610 ptr=00000000f78cb7b5 name=sock_inode_cache
... kmem_cache_free: call_site=rcu_core+0x1fd/0x610 ptr=0000000018768985 name=pool_workqueue
... kmem_cache_free: call_site=rcu_core+0x1fd/0x610 ptr=000000006a6cb484 name=radix_tree_node
We can use it to understand what the RCU core is going to free. For
example, some users maybe interested in when the RCU core starts
freeing reclaimable slabs like dentry to reduce memory pressure.
Link: https://lkml.kernel.org/r/20201216072804.8838-1-jian.w.wen@oracle.com
Signed-off-by: Jacob Wen <jian.w.wen@oracle.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: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull RCU updates from Paul E. McKenney:
- Documentation updates.
- Miscellaneous fixes.
- kfree_rcu() updates: Addition of mem_dump_obj() to provide allocator return
addresses to more easily locate bugs. This has a couple of RCU-related commits,
but is mostly MM. Was pulled in with akpm's agreement.
- Per-callback-batch tracking of numbers of callbacks,
which enables better debugging information and smarter
reactions to large numbers of callbacks.
- The first round of changes to allow CPUs to be runtime switched from and to
callback-offloaded state.
- CONFIG_PREEMPT_RT-related changes.
- RCU CPU stall warning updates.
- Addition of polling grace-period APIs for SRCU.
- Torture-test and torture-test scripting updates, including a "torture everything"
script that runs rcutorture, locktorture, scftorture, rcuscale, and refscale.
Plus does an allmodconfig build.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When creating a new kmem cache, SLUB determines how large the slab pages
will based on number of inputs, including the number of CPUs in the
system. Larger slab pages mean that more objects can be allocated/free
from per-cpu slabs before accessing shared structures, but also
potentially more memory can be wasted due to low slab usage and
fragmentation. The rough idea of using number of CPUs is that larger
systems will be more likely to benefit from reduced contention, and also
should have enough memory to spare.
Number of CPUs used to be determined as nr_cpu_ids, which is number of
possible cpus, but on some systems many will never be onlined, thus
commit 045ab8c948 ("mm/slub: let number of online CPUs determine the
slub page order") changed it to nr_online_cpus(). However, for kmem
caches created early before CPUs are onlined, this may lead to
permamently low slab page sizes.
Vincent reports a regression [1] of hackbench on arm64 systems:
"I'm facing significant performances regression on a large arm64
server system (224 CPUs). Regressions is also present on small arm64
system (8 CPUs) but in a far smaller order of magnitude
On 224 CPUs system : 9 iterations of hackbench -l 16000 -g 16
v5.11-rc4 : 9.135sec (+/- 0.45%)
v5.11-rc4 + revert this patch: 3.173sec (+/- 0.48%)
v5.10: 3.136sec (+/- 0.40%)"
Mel reports a regression [2] of hackbench on x86_64, with lockstat suggesting
page allocator contention:
"i.e. the patch incurs a 7% to 32% performance penalty. This bisected
cleanly yesterday when I was looking for the regression and then
found the thread.
Numerous caches change size. For example, kmalloc-512 goes from
order-0 (vanilla) to order-2 with the revert.
So mostly this is down to the number of times SLUB calls into the
page allocator which only caches order-0 pages on a per-cpu basis"
Clearly num_online_cpus() doesn't work too early in bootup. We could
change the order dynamically in a memory hotplug callback, but runtime
order changing for existing kmem caches has been already shown as
dangerous, and removed in 32a6f409b6 ("mm, slub: remove runtime
allocation order changes").
It could be resurrected in a safe manner with some effort, but to fix
the regression we need something simpler.
We could use num_present_cpus() that should be the number of physically
present CPUs even before they are onlined. That would work for PowerPC
[3], which triggered the original commit, but that still doesn't work on
arm64 [4] as explained in [5].
So this patch tries to determine the best available value without
specific arch knowledge.
- num_present_cpus() if the number is larger than 1, as that means the
arch is likely setting it properly
- nr_cpu_ids otherwise
This should fix the reported regressions while also keeping the effect
of 045ab8c948 for PowerPC systems. It's possible there are
configurations where num_present_cpus() is 1 during boot while
nr_cpu_ids is at the same time bloated, so these (if they exist) would
keep the large orders based on nr_cpu_ids as was before 045ab8c948.
[1] https://lore.kernel.org/linux-mm/CAKfTPtA_JgMf_+zdFbcb_V9rM7JBWNPjAz9irgwFj7Rou=xzZg@mail.gmail.com/
[2] https://lore.kernel.org/linux-mm/20210128134512.GF3592@techsingularity.net/
[3] https://lore.kernel.org/linux-mm/20210123051607.GC2587010@in.ibm.com/
[4] https://lore.kernel.org/linux-mm/CAKfTPtAjyVmS5VYvU6DBxg4-JEo5bdmWbngf-03YsY18cmWv_g@mail.gmail.com/
[5] https://lore.kernel.org/linux-mm/20210126230305.GD30941@willie-the-truck/
Link: https://lkml.kernel.org/r/20210208134108.22286-1-vbabka@suse.cz
Fixes: 045ab8c948 ("mm/slub: let number of online CPUs determine the slub page order")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Vincent Guittot <vincent.guittot@linaro.org>
Reported-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jann Horn <jannh@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit dde3c6b72a.
syzbot report a double-free bug. The following case can cause this bug.
- mm/slab_common.c: create_cache(): if the __kmem_cache_create() fails,
it does:
out_free_cache:
kmem_cache_free(kmem_cache, s);
- but __kmem_cache_create() - at least for slub() - will have done
sysfs_slab_add(s)
-> sysfs_create_group() .. fails ..
-> kobject_del(&s->kobj); .. which frees s ...
We can't remove the kmem_cache_free() in create_cache(), because other
error cases of __kmem_cache_create() do not free this.
So, revert the commit dde3c6b72a ("mm/slub: fix a memory leak in
sysfs_slab_add()") to fix this.
Reported-by: syzbot+d0bd96b4696c1ef67991@syzkaller.appspotmail.com
Fixes: dde3c6b72a ("mm/slub: fix a memory leak in sysfs_slab_add()")
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A few places where SLUB accesses object's data or metadata were missed
in a previous patch. This leads to false positives with hardware
tag-based KASAN when bulk allocations are used with init_on_alloc/free.
Fix the false-positives by resetting pointer tags during these accesses.
(The kasan_reset_tag call is removed from slab_alloc_node, as it's added
into maybe_wipe_obj_freeptr.)
Link: https://linux-review.googlesource.com/id/I50dd32838a666e173fe06c3c5c766f2c36aae901
Link: https://lkml.kernel.org/r/093428b5d2ca8b507f4a79f92f9929b35f7fada7.1610731872.git.andreyknvl@google.com
Fixes: aa1ef4d7b3 ("kasan, mm: reset tags when accessing metadata")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are kernel facilities such as per-CPU reference counts that give
error messages in generic handlers or callbacks, whose messages are
unenlightening. In the case of per-CPU reference-count underflow, this
is not a problem when creating a new use of this facility because in that
case the bug is almost certainly in the code implementing that new use.
However, trouble arises when deploying across many systems, which might
exercise corner cases that were not seen during development and testing.
Here, it would be really nice to get some kind of hint as to which of
several uses the underflow was caused by.
This commit therefore exposes a mem_dump_obj() function that takes
a pointer to memory (which must still be allocated if it has been
dynamically allocated) and prints available information on where that
memory came from. This pointer can reference the middle of the block as
well as the beginning of the block, as needed by things like RCU callback
functions and timer handlers that might not know where the beginning of
the memory block is. These functions and handlers can use mem_dump_obj()
to print out better hints as to where the problem might lie.
The information printed can depend on kernel configuration. For example,
the allocation return address can be printed only for slab and slub,
and even then only when the necessary debug has been enabled. For slab,
build with CONFIG_DEBUG_SLAB=y, and either use sizes with ample space
to the next power of two or use the SLAB_STORE_USER when creating the
kmem_cache structure. For slub, build with CONFIG_SLUB_DEBUG=y and
boot with slub_debug=U, or pass SLAB_STORE_USER to kmem_cache_create()
if more focused use is desired. Also for slub, use CONFIG_STACKTRACE
to enable printing of the allocation-time stack trace.
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: <linux-mm@kvack.org>
Reported-by: Andrii Nakryiko <andrii@kernel.org>
[ paulmck: Convert to printing and change names per Joonsoo Kim. ]
[ paulmck: Move slab definition per Stephen Rothwell and kbuild test robot. ]
[ paulmck: Handle CONFIG_MMU=n case where vmalloc() is kmalloc(). ]
[ paulmck: Apply Vlastimil Babka feedback on slab.c kmem_provenance(). ]
[ paulmck: Extract more info from !SLUB_DEBUG per Joonsoo Kim. ]
[ paulmck: Explicitly check for small pointers per Naresh Kamboju. ]
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
acquire_slab() fails if there is contention on the freelist of the page
(probably because some other CPU is concurrently freeing an object from
the page). In that case, it might make sense to look for a different page
(since there might be more remote frees to the page from other CPUs, and
we don't want contention on struct page).
However, the current code accidentally stops looking at the partial list
completely in that case. Especially on kernels without CONFIG_NUMA set,
this means that get_partial() fails and new_slab_objects() falls back to
new_slab(), allocating new pages. This could lead to an unnecessary
increase in memory fragmentation.
Link: https://lkml.kernel.org/r/20201228130853.1871516-1-jannh@google.com
Fixes: 7ced371971 ("slub: Acquire_slab() avoid loop")
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's convenient to have page->objects initialized before calling into
account_slab_page(). In particular, this information can be used to
pre-alloc the obj_cgroup vector.
Let's call account_slab_page() a bit later, after the initialization of
page->objects.
This commit doesn't bring any functional change, but is required for
further optimizations.
[akpm@linux-foundation.org: undo changes needed by forthcoming mm-memcg-slab-pre-allocate-obj_cgroups-for-slab-caches-with-slab_account.patch]
Link: https://lkml.kernel.org/r/20201110195753.530157-1-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Kernel allocator code accesses metadata for slab objects, that may lie
out-of-bounds of the object itself, or be accessed when an object is
freed. Such accesses trigger tag faults and lead to false-positive
reports with hardware tag-based KASAN.
Software KASAN modes disable instrumentation for allocator code via
KASAN_SANITIZE Makefile macro, and rely on kasan_enable/disable_current()
annotations which are used to ignore KASAN reports.
With hardware tag-based KASAN neither of those options are available, as
it doesn't use compiler instrumetation, no tag faults are ignored, and MTE
is disabled after the first one.
Instead, reset tags when accessing metadata (currently only for SLUB).
Link: https://lkml.kernel.org/r/a0f3cefbc49f34c843b664110842de4db28179d0.1606161801.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Vasily Gorbik <gor@linux.ibm.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>
Convert the unbounded uses of sprintf to sysfs_emit.
A few conversions may now not end in a newline if the output buffer is
overflowed.
Link: https://lkml.kernel.org/r/0c90a90f466167f8c37de4b737553cf49c4a277f.1605376435.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page order of the slab that gets chosen for a given slab cache depends
on the number of objects that can be fit in the slab while meeting other
requirements. We start with a value of minimum objects based on
nr_cpu_ids that is driven by possible number of CPUs and hence could be
higher than the actual number of CPUs present in the system. This leads
to calculate_order() chosing a page order that is on the higher side
leading to increased slab memory consumption on systems that have bigger
page sizes.
Hence rely on the number of online CPUs when determining the mininum
objects, thereby increasing the chances of chosing a lower conservative
page order for the slab.
Vlastimil said:
"Ideally, we would react to hotplug events and update existing caches
accordingly. But for that, recalculation of order for existing caches
would have to be made safe, while not affecting hot paths. We have
removed the sysfs interface with 32a6f409b6 ("mm, slub: remove
runtime allocation order changes") as it didn't seem easy and worth
the trouble.
In case somebody wants to start with a large order right from the
boot because they know they will hotplug lots of cpus later, they can
use slub_min_objects= boot param to override this heuristic. So in
case this change regresses somebody's performance, there's a way
around it and thus the risk is low IMHO"
Link: https://lkml.kernel.org/r/20201118082759.1413056-1-bharata@linux.ibm.com
Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 9cf7a11183 ("mm/slub: make add_full() condition more explicit")
replaced an unnecessarily generic kmem_cache_debug(s) check with an
explicit check of SLAB_STORE_USER and #ifdef CONFIG_SLUB_DEBUG.
We can achieve the same specific check with the recently added
kmem_cache_debug_flags() which removes the #ifdef and restores the
no-branch-overhead benefit of static key check when slub debugging is not
enabled.
Link: https://lkml.kernel.org/r/3ef24214-38c7-1238-8296-88caf7f48ab6@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Abel Wu <wuyun.wu@huawei.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Liu Xiang <liu.xiang6@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page allocator expects that page->mapping is NULL for a page being
freed. SLAB and SLUB use the slab_cache field which is in union with
mapping, but before freeing the page, the field is referenced with the
"mapping" name when set to NULL.
It's IMHO more correct (albeit functionally the same) to use the
slab_cache name as that's the field we use in SL*B, and document why we
clear it in a comment (we don't clear fields such as s_mem or freelist, as
page allocator doesn't care about those). While using the 'mapping' name
would automagically keep the code correct if the unions in struct page
changed, such changes should be done consciously and needed changes
evaluated - the comment should help with that.
Link: https://lkml.kernel.org/r/20201210160020.21562-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
