Many developers already know that field for reference count of the
struct page is _count and atomic type.  They would try to handle it
directly and this could break the purpose of page reference count
tracepoint.  To prevent direct _count modification, this patch rename it
to _refcount and add warning message on the code.  After that, developer
who need to handle reference count will find that field should not be
accessed directly.

[akpm@linux-foundation.org: fix comments, per Vlastimil]
[akpm@linux-foundation.org: Documentation/vm/transhuge.txt too]
[sfr@canb.auug.org.au: sync ethernet driver changes]
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Sunil Goutham <sgoutham@cavium.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Manish Chopra <manish.chopra@qlogic.com>
Cc: Yuval Mintz <yuval.mintz@qlogic.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Cc: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

page_reference manipulation functions are introduced to track down
reference count change of the page.  Use it instead of direct
modification of _count.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Sunil Goutham <sgoutham@cavium.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

/sys/kernel/slab/xx/defrag_ratio should be remote_node_defrag_ratio.

Link: http://lkml.kernel.org/r/1463449242-5366-1-git-send-email-lip@dtdream.comSigned-off-by: NLi Peng <lip@dtdream.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Now we have IS_ENABLED helper to check if a Kconfig option is enabled or
not, so ZONE_DMA_FLAG sounds no longer useful.

And, the use of ZONE_DMA_FLAG in slab looks pointless according to the
comment [1] from Johannes Weiner, so remove them and ORing passed in
flags with the cache gfp flags has been done in kmem_getpages().

[1] https://lkml.org/lkml/2014/9/25/553

Link: http://lkml.kernel.org/r/1462381297-11009-1-git-send-email-yang.shi@linaro.orgSigned-off-by: NYang Shi <yang.shi@linaro.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Provides an optional config (CONFIG_SLAB_FREELIST_RANDOM) to randomize
the SLAB freelist.  The list is randomized during initialization of a
new set of pages.  The order on different freelist sizes is pre-computed
at boot for performance.  Each kmem_cache has its own randomized
freelist.  Before pre-computed lists are available freelists are
generated dynamically.  This security feature reduces the predictability
of the kernel SLAB allocator against heap overflows rendering attacks
much less stable.

For example this attack against SLUB (also applicable against SLAB)
would be affected:

  https://jon.oberheide.org/blog/2010/09/10/linux-kernel-can-slub-overflow/

Also, since v4.6 the freelist was moved at the end of the SLAB.  It
means a controllable heap is opened to new attacks not yet publicly
discussed.  A kernel heap overflow can be transformed to multiple
use-after-free.  This feature makes this type of attack harder too.

To generate entropy, we use get_random_bytes_arch because 0 bits of
entropy is available in the boot stage.  In the worse case this function
will fallback to the get_random_bytes sub API.  We also generate a shift
random number to shift pre-computed freelist for each new set of pages.

The config option name is not specific to the SLAB as this approach will
be extended to other allocators like SLUB.

Performance results highlighted no major changes:

Hackbench (running 90 10 times):

  Before average: 0.0698
  After average: 0.0663 (-5.01%)

slab_test 1 run on boot.  Difference only seen on the 2048 size test
being the worse case scenario covered by freelist randomization.  New
slab pages are constantly being created on the 10000 allocations.
Variance should be mainly due to getting new pages every few
allocations.

Before:

  Single thread testing
  =====================
  1. Kmalloc: Repeatedly allocate then free test
  10000 times kmalloc(8) -> 99 cycles kfree -> 112 cycles
  10000 times kmalloc(16) -> 109 cycles kfree -> 140 cycles
  10000 times kmalloc(32) -> 129 cycles kfree -> 137 cycles
  10000 times kmalloc(64) -> 141 cycles kfree -> 141 cycles
  10000 times kmalloc(128) -> 152 cycles kfree -> 148 cycles
  10000 times kmalloc(256) -> 195 cycles kfree -> 167 cycles
  10000 times kmalloc(512) -> 257 cycles kfree -> 199 cycles
  10000 times kmalloc(1024) -> 393 cycles kfree -> 251 cycles
  10000 times kmalloc(2048) -> 649 cycles kfree -> 228 cycles
  10000 times kmalloc(4096) -> 806 cycles kfree -> 370 cycles
  10000 times kmalloc(8192) -> 814 cycles kfree -> 411 cycles
  10000 times kmalloc(16384) -> 892 cycles kfree -> 455 cycles
  2. Kmalloc: alloc/free test
  10000 times kmalloc(8)/kfree -> 121 cycles
  10000 times kmalloc(16)/kfree -> 121 cycles
  10000 times kmalloc(32)/kfree -> 121 cycles
  10000 times kmalloc(64)/kfree -> 121 cycles
  10000 times kmalloc(128)/kfree -> 121 cycles
  10000 times kmalloc(256)/kfree -> 119 cycles
  10000 times kmalloc(512)/kfree -> 119 cycles
  10000 times kmalloc(1024)/kfree -> 119 cycles
  10000 times kmalloc(2048)/kfree -> 119 cycles
  10000 times kmalloc(4096)/kfree -> 121 cycles
  10000 times kmalloc(8192)/kfree -> 119 cycles
  10000 times kmalloc(16384)/kfree -> 119 cycles

After:

  Single thread testing
  =====================
  1. Kmalloc: Repeatedly allocate then free test
  10000 times kmalloc(8) -> 130 cycles kfree -> 86 cycles
  10000 times kmalloc(16) -> 118 cycles kfree -> 86 cycles
  10000 times kmalloc(32) -> 121 cycles kfree -> 85 cycles
  10000 times kmalloc(64) -> 176 cycles kfree -> 102 cycles
  10000 times kmalloc(128) -> 178 cycles kfree -> 100 cycles
  10000 times kmalloc(256) -> 205 cycles kfree -> 109 cycles
  10000 times kmalloc(512) -> 262 cycles kfree -> 136 cycles
  10000 times kmalloc(1024) -> 342 cycles kfree -> 157 cycles
  10000 times kmalloc(2048) -> 701 cycles kfree -> 238 cycles
  10000 times kmalloc(4096) -> 803 cycles kfree -> 364 cycles
  10000 times kmalloc(8192) -> 835 cycles kfree -> 404 cycles
  10000 times kmalloc(16384) -> 896 cycles kfree -> 441 cycles
  2. Kmalloc: alloc/free test
  10000 times kmalloc(8)/kfree -> 121 cycles
  10000 times kmalloc(16)/kfree -> 121 cycles
  10000 times kmalloc(32)/kfree -> 123 cycles
  10000 times kmalloc(64)/kfree -> 142 cycles
  10000 times kmalloc(128)/kfree -> 121 cycles
  10000 times kmalloc(256)/kfree -> 119 cycles
  10000 times kmalloc(512)/kfree -> 119 cycles
  10000 times kmalloc(1024)/kfree -> 119 cycles
  10000 times kmalloc(2048)/kfree -> 119 cycles
  10000 times kmalloc(4096)/kfree -> 119 cycles
  10000 times kmalloc(8192)/kfree -> 119 cycles
  10000 times kmalloc(16384)/kfree -> 119 cycles

[akpm@linux-foundation.org: propagate gfp_t into cache_random_seq_create()]
Signed-off-by: NThomas Garnier <thgarnie@google.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: Laura Abbott <labbott@fedoraproject.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When we call __kmem_cache_shrink on memory cgroup removal, we need to
synchronize kmem_cache->cpu_partial update with put_cpu_partial that
might be running on other cpus.  Currently, we achieve that by using
kick_all_cpus_sync, which works as a system wide memory barrier.  Though
fast it is, this method has a flaw - it issues a lot of IPIs, which
might hurt high performance or real-time workloads.

To fix this, let's replace kick_all_cpus_sync with synchronize_sched.
Although the latter one may take much longer to finish, it shouldn't be
a problem in this particular case, because memory cgroups are destroyed
asynchronously from a workqueue so that no user visible effects should
be introduced.  OTOH, it will save us from excessive IPIs when someone
removes a cgroup.

Anyway, even if using synchronize_sched turns out to take too long, we
can always introduce a kind of __kmem_cache_shrink batching so that this
method would only be called once per one cgroup destruction (not per
each per memcg kmem cache as it is now).
Signed-off-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Reported-by: NPeter Zijlstra <peterz@infradead.org>
Suggested-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

To check whether free objects exist or not precisely, we need to grab a
lock.  But, accuracy isn't that important because race window would be
even small and if there is too much free object, cache reaper would reap
it.  So, this patch makes the check for free object exisistence not to
hold a lock.  This will reduce lock contention in heavily allocation
case.

Note that until now, n->shared can be freed during the processing by
writing slabinfo, but, with some trick in this patch, we can access it
freely within interrupt disabled period.

Below is the result of concurrent allocation/free in slab allocation
benchmark made by Christoph a long time ago.  I make the output simpler.
The number shows cycle count during alloc/free respectively so less is
better.

  * Before
  Kmalloc N*alloc N*free(32): Average=248/966
  Kmalloc N*alloc N*free(64): Average=261/949
  Kmalloc N*alloc N*free(128): Average=314/1016
  Kmalloc N*alloc N*free(256): Average=741/1061
  Kmalloc N*alloc N*free(512): Average=1246/1152
  Kmalloc N*alloc N*free(1024): Average=2437/1259
  Kmalloc N*alloc N*free(2048): Average=4980/1800
  Kmalloc N*alloc N*free(4096): Average=9000/2078

  * After
  Kmalloc N*alloc N*free(32): Average=344/792
  Kmalloc N*alloc N*free(64): Average=347/882
  Kmalloc N*alloc N*free(128): Average=390/959
  Kmalloc N*alloc N*free(256): Average=393/1067
  Kmalloc N*alloc N*free(512): Average=683/1229
  Kmalloc N*alloc N*free(1024): Average=1295/1325
  Kmalloc N*alloc N*free(2048): Average=2513/1664
  Kmalloc N*alloc N*free(4096): Average=4742/2172

It shows that allocation performance decreases for the object size up to
128 and it may be due to extra checks in cache_alloc_refill().  But,
with considering improvement of free performance, net result looks the
same.  Result for other size class looks very promising, roughly, 50%
performance improvement.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Until now, cache growing makes a free slab on node's slab list and then
we can allocate free objects from it.  This necessarily requires to hold
a node lock which is very contended.  If we refill cpu cache before
attaching it to node's slab list, we can avoid holding a node lock as
much as possible because this newly allocated slab is only visible to
the current task.  This will reduce lock contention.

Below is the result of concurrent allocation/free in slab allocation
benchmark made by Christoph a long time ago.  I make the output simpler.
The number shows cycle count during alloc/free respectively so less is
better.

  * Before
  Kmalloc N*alloc N*free(32): Average=355/750
  Kmalloc N*alloc N*free(64): Average=452/812
  Kmalloc N*alloc N*free(128): Average=559/1070
  Kmalloc N*alloc N*free(256): Average=1176/980
  Kmalloc N*alloc N*free(512): Average=1939/1189
  Kmalloc N*alloc N*free(1024): Average=3521/1278
  Kmalloc N*alloc N*free(2048): Average=7152/1838
  Kmalloc N*alloc N*free(4096): Average=13438/2013

  * After
  Kmalloc N*alloc N*free(32): Average=248/966
  Kmalloc N*alloc N*free(64): Average=261/949
  Kmalloc N*alloc N*free(128): Average=314/1016
  Kmalloc N*alloc N*free(256): Average=741/1061
  Kmalloc N*alloc N*free(512): Average=1246/1152
  Kmalloc N*alloc N*free(1024): Average=2437/1259
  Kmalloc N*alloc N*free(2048): Average=4980/1800
  Kmalloc N*alloc N*free(4096): Average=9000/2078

It shows that contention is reduced for all the object sizes and
performance increases by 30 ~ 40%.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is a preparation step to implement lockless allocation path when
there is no free objects in kmem_cache.

What we'd like to do here is to refill cpu cache without holding a node
lock.  To accomplish this purpose, refill should be done after new slab
allocation but before attaching the slab to the management list.  So,
this patch separates cache_grow() to two parts, allocation and attaching
to the list in order to add some code inbetween them in the following
patch.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, cache_grow() assumes that allocated page's nodeid would be
same with parameter nodeid which is used for allocation request.  If we
discard this assumption, we can handle fallback_alloc() case gracefully.
So, this patch makes cache_grow() handle the page allocated on arbitrary
node and clean-up relevant code.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Slab color isn't needed to be changed strictly.  Because locking for
changing slab color could cause more lock contention so this patch
implements racy access/modify the slab color.  This is a preparation
step to implement lockless allocation path when there is no free objects
in the kmem_cache.

Below is the result of concurrent allocation/free in slab allocation
benchmark made by Christoph a long time ago.  I make the output simpler.
The number shows cycle count during alloc/free respectively so less is
better.

  * Before
  Kmalloc N*alloc N*free(32): Average=365/806
  Kmalloc N*alloc N*free(64): Average=452/690
  Kmalloc N*alloc N*free(128): Average=736/886
  Kmalloc N*alloc N*free(256): Average=1167/985
  Kmalloc N*alloc N*free(512): Average=2088/1125
  Kmalloc N*alloc N*free(1024): Average=4115/1184
  Kmalloc N*alloc N*free(2048): Average=8451/1748
  Kmalloc N*alloc N*free(4096): Average=16024/2048

  * After
  Kmalloc N*alloc N*free(32): Average=355/750
  Kmalloc N*alloc N*free(64): Average=452/812
  Kmalloc N*alloc N*free(128): Average=559/1070
  Kmalloc N*alloc N*free(256): Average=1176/980
  Kmalloc N*alloc N*free(512): Average=1939/1189
  Kmalloc N*alloc N*free(1024): Average=3521/1278
  Kmalloc N*alloc N*free(2048): Average=7152/1838
  Kmalloc N*alloc N*free(4096): Average=13438/2013

It shows that contention is reduced for object size >= 1024 and
performance increases by roughly 15%.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, determination to free a slab is done whenever each freed
object is put into the slab.  This has a following problem.

Assume free_limit = 10 and nr_free = 9.

Free happens as following sequence and nr_free changes as following.

free(become a free slab) free(not become a free slab) nr_free: 9 -> 10
(at first free) -> 11 (at second free)

If we try to check if we can free current slab or not on each object
free, we can't free any slab in this situation because current slab
isn't a free slab when nr_free exceed free_limit (at second free) even
if there is a free slab.

However, if we check it lastly, we can free 1 free slab.

This problem would cause to keep too much memory in the slab subsystem.
This patch try to fix it by checking number of free object after all
free work is done.  If there is free slab at that time, we can free slab
as much as possible so we keep free slab as minimal.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There are mostly same code for setting up kmem_cache_node either in
cpuup_prepare() or alloc_kmem_cache_node().  Factor out and clean-up
them.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Tested-by: NNishanth Menon <nm@ti.com>
Tested-by: NJon Hunter <jonathanh@nvidia.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It can be reused on other place, so factor out it.  Following patch will
use it.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

slabs_tofree() implies freeing all free slab.  We can do it with just
providing INT_MAX.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Initial attemp to remove BAD_ALIEN_MAGIC is once reverted by 'commit
edcad250 ("Revert "slab: remove BAD_ALIEN_MAGIC"")' because it
causes a problem on m68k which has many node but !CONFIG_NUMA.  In this
case, although alien cache isn't used at all but to cope with some
initialization path, garbage value is used and that is BAD_ALIEN_MAGIC.
Now, this patch set use_alien_caches to 0 when !CONFIG_NUMA, there is no
initialization path problem so we don't need BAD_ALIEN_MAGIC at all.  So
remove it.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Tested-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

While processing concurrent allocation, SLAB could be contended a lot
because it did a lots of work with holding a lock.  This patchset try to
reduce the number of critical section to reduce lock contention.  Major
changes are lockless decision to allocate more slab and lockless cpu
cache refill from the newly allocated slab.

Below is the result of concurrent allocation/free in slab allocation
benchmark made by Christoph a long time ago.  I make the output simpler.
The number shows cycle count during alloc/free respectively so less is
better.

  * Before
  Kmalloc N*alloc N*free(32): Average=365/806
  Kmalloc N*alloc N*free(64): Average=452/690
  Kmalloc N*alloc N*free(128): Average=736/886
  Kmalloc N*alloc N*free(256): Average=1167/985
  Kmalloc N*alloc N*free(512): Average=2088/1125
  Kmalloc N*alloc N*free(1024): Average=4115/1184
  Kmalloc N*alloc N*free(2048): Average=8451/1748
  Kmalloc N*alloc N*free(4096): Average=16024/2048

  * After
  Kmalloc N*alloc N*free(32): Average=344/792
  Kmalloc N*alloc N*free(64): Average=347/882
  Kmalloc N*alloc N*free(128): Average=390/959
  Kmalloc N*alloc N*free(256): Average=393/1067
  Kmalloc N*alloc N*free(512): Average=683/1229
  Kmalloc N*alloc N*free(1024): Average=1295/1325
  Kmalloc N*alloc N*free(2048): Average=2513/1664
  Kmalloc N*alloc N*free(4096): Average=4742/2172

It shows that performance improves greatly (roughly more than 50%) for
the object class whose size is more than 128 bytes.

This patch (of 11):

If we don't hold neither the slab_mutex nor the node lock, node's shared
array cache could be freed and re-populated.  If __kmem_cache_shrink()
is called at the same time, it will call drain_array() with n->shared
without holding node lock so problem can happen.  This patch fix the
situation by holding the node lock before trying to drain the shared
array.

In addition, add a debug check to confirm that n->shared access race
doesn't exist.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A recent cleanup removed some exported functions that were not used
anywhere, which in turn exposed the fact that some other functions in
the same file are only used in some configurations.

We now get a warning about them when CONFIG_HOTPLUG_CPU is disabled:

  kernel/padata.c:670:12: error: '__padata_remove_cpu' defined but not used [-Werror=unused-function]
   static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)
              ^~~~~~~~~~~~~~~~~~~
  kernel/padata.c:650:12: error: '__padata_add_cpu' defined but not used [-Werror=unused-function]
   static int __padata_add_cpu(struct padata_instance *pinst, int cpu)

This rearranges the code so the __padata_remove_cpu/__padata_add_cpu
functions are within the #ifdef that protects the code that calls them.

[akpm@linux-foundation.org: coding-style fixes]
Fixes: 4ba6d78c671e ("kernel/padata.c: removed unused code")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Cc: Richard Cochran <rcochran@linutronix.de>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

By accident I stumbled across code that has never been used.  This
driver has EXPORT_SYMBOL functions, and the only user of the code is
pcrypt.c, but this only uses a subset of the exported symbols.

According to 'git log -G', the functions, padata_set_cpumasks,
padata_add_cpu, and padata_remove_cpu have never been used since they
were first introduced.  This patch removes the unused code.

On one 64 bit build, with CRYPTO_PCRYPT built in, the text is more than
4k smaller.

  kbuild_hp> size $KBUILD_OUTPUT/vmlinux
      text    data     bss      dec hex    filename
  10566658 4678360 1122304 16367322 f9beda vmlinux
  10561984 4678360 1122304 16362648 f9ac98 vmlinux

On another config, 32 bit, the saving is about 0.5k bytes.

  kbuild_hp-x86> size $KBUILD_OUTPUT/vmlinux
  6012005 2409513 2785280 11206798 ab008e vmlinux
  6011491 2409513 2785280 11206284 aafe8c vmlinux
Signed-off-by: NRichard Cochran <rcochran@linutronix.de>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The goto is not useful in ocfs2_put_slot(), so delete it.
Signed-off-by: NGuozhonghua <guozhonghua@h3c.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Clean up unused parameter 'count' in o2hb_read_block_input().
Signed-off-by: NJun Piao <piaojun@huawei.com>
Reviewed-by: NJoseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Clean up an unused variable 'wants_rotate' in ocfs2_truncate_rec.
Signed-off-by: NJun Piao <piaojun@huawei.com>
Reviewed-by: NJoseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The comment in ocfs2_extended_slot has the offset wrong.

Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When activating a static object we need make sure that the object is
tracked in the object tracker.  If it is a non-static object then the
activation is illegal.

In previous implementation, each subsystem need take care of this in
their fixup callbacks.  Actually we can put it into debugobjects core.
Thus we can save duplicated code, and have *pure* fixup callbacks.

To achieve this, a new callback "is_static_object" is introduced to let
the type specific code decide whether a object is static or not.  If
yes, we take it into object tracker, otherwise give warning and invoke
fixup callback.

This change has paassed debugobjects selftest, and I also do some test
with all debugobjects supports enabled.

At last, I have a concern about the fixups that can it change the object
which is in incorrect state on fixup? Because the 'addr' may not point
to any valid object if a non-static object is not tracked.  Then Change
such object can overwrite someone's memory and cause unexpected
behaviour.  For example, the timer_fixup_activate bind timer to function
stub_timer.

Link: http://lkml.kernel.org/r/1462576157-14539-1-git-send-email-changbin.du@intel.com
[changbin.du@intel.com: improve code comments where invoke the new is_static_object callback]
  Link: http://lkml.kernel.org/r/1462777431-8171-1-git-send-email-changbin.du@intel.comSigned-off-by: NDu, Changbin <changbin.du@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Update documentation creangponding to change(debugobjects: make fixup
functions return bool instead of int).
Signed-off-by: NDu, Changbin <changbin.du@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Update the return type to use bool instead of int, corresponding to
cheange (debugobjects: make fixup functions return bool instead of int).
Signed-off-by: NDu, Changbin <changbin.du@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Update the return type to use bool instead of int, corresponding to
cheange (debugobjects: make fixup functions return bool instead of int).
Signed-off-by: NDu, Changbin <changbin.du@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Update the return type to use bool instead of int, corresponding to
cheange (debugobjects: make fixup functions return bool instead of int).
Signed-off-by: NDu, Changbin <changbin.du@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Update the return type to use bool instead of int, corresponding to
change (debugobjects: make fixup functions return bool instead of int)
Signed-off-by: NDu, Changbin <changbin.du@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If debug_object_fixup() return non-zero when problem has been fixed.
But the code got it backwards, it taks 0 as fixup successfully.  So fix
it.
Signed-off-by: NDu, Changbin <changbin.du@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I am going to introduce debugobjects infrastructure to USB subsystem.
But before this, I found the code of debugobjects could be improved.
This patchset will make fixup functions return bool type instead of int.
Because fixup only need report success or no.  boolean is the 'real'
type.

This patch (of 7):

The object debugging infrastructure core provides some fixup callbacks
for the subsystem who use it.  These callbacks are called from the debug
code whenever a problem in debug_object_init is detected.  And
debugobjects core suppose them returns 1 when the fixup was successful,
otherwise 0.  So the return type is boolean.

A bad thing is that debug_object_fixup use the return value for
arithmetic operation.  It confused me that what is the reall return
type.

Reading over the whole code, I found some place do use the return value
incorrectly(see next patch).  So why use bool type instead?
Signed-off-by: NDu, Changbin <changbin.du@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This adds an additional line of output (to reduce the chances of
breaking any existing output parsers) which prints the total size before
and after and the relative difference.

  add/remove: 39/0 grow/shrink: 12408/55 up/down: 362227/-1430 (360797)
  function                                     old     new   delta
  ext4_fill_super                            10556   12590   +2034
  _fpadd_parts                                   -    1186   +1186
  ntfs_fill_super                             5340    6164    +824
  ...
  ...
  __divdf3                                     752     386    -366
  unlzma                                      3682    3274    -408
  Total: Before=5023101, After=5383898, chg 7.000000%
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Link: http://lkml.kernel.org/r/1463124110-30314-1-git-send-email-vgupta@synopsys.comSigned-off-by: NVineet Gupta <vgupta@synopsys.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A few instances of "fimware" instead of "firmware" were found.  Fix
these and add it to the spelling.txt file.
Signed-off-by: NKees Cook <keescook@chromium.org>
Reported-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scripts/decode_stacktrace.sh presently displays module symbols as

	func+0x0ff/0x5153 [module]

Add a third argument: the pathname of a directory where the script
should look for the file module.ko so that the output appears as

	func (foo/bar.c:123) module

Without the argument or if the module file isn't found the script prints
such symbols as is without decoding.
Signed-off-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

All references to timespec_add_safe() now use timespec64_add_safe().

The plan is to replace struct timespec references with struct timespec64
throughout the kernel as timespec is not y2038 safe.

Drop timespec_add_safe() and use timespec64_add_safe() for all
architectures.

Link: http://lkml.kernel.org/r/1461947989-21926-4-git-send-email-deepa.kernel@gmail.comSigned-off-by: NDeepa Dinamani <deepa.kernel@gmail.com>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

struct timespec is not y2038 safe.  Even though timespec might be
sufficient to represent timeouts, use struct timespec64 here as the plan
is to get rid of all timespec reference in the kernel.

The patch transitions the common functions: poll_select_set_timeout()
and select_estimate_accuracy() to use timespec64.  And, all the syscalls
that use these functions are transitioned in the same patch.

The restart block parameters for poll uses monotonic time.  Use
timespec64 here as well to assign timeout value.  This parameter in the
restart block need not change because this only holds the monotonic
timestamp at which timeout should occur.  And, unsigned long data type
should be big enough for this timestamp.

The system call interfaces will be handled in a separate series.

Compat interfaces need not change as timespec64 is an alias to struct
timespec on a 64 bit system.

Link: http://lkml.kernel.org/r/1461947989-21926-3-git-send-email-deepa.kernel@gmail.comSigned-off-by: NDeepa Dinamani <deepa.kernel@gmail.com>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

timespec64_add_safe() has been defined in time64.h for 64 bit systems.
But, 32 bit systems only have an extern function prototype defined.
Provide a definition for the above function.

The function will be necessary as part of y2038 changes.  struct
timespec is not y2038 safe.  All references to timespec will be replaced
by struct timespec64.  The function is meant to be a replacement for
timespec_add_safe().

The implementation is similar to timespec_add_safe().

Link: http://lkml.kernel.org/r/1461947989-21926-2-git-send-email-deepa.kernel@gmail.comSigned-off-by: NDeepa Dinamani <deepa.kernel@gmail.com>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Inotify instance is destroyed when all references to it are dropped.
That not only means that the corresponding file descriptor needs to be
closed but also that all corresponding instance marks are freed (as each
mark holds a reference to the inotify instance).  However marks are
freed only after SRCU period ends which can take some time and thus if
user rapidly creates and frees inotify instances, number of existing
inotify instances can exceed max_user_instances limit although from user
point of view there is always at most one existing instance.  Thus
inotify_init() returns EMFILE error which is hard to justify from user
point of view.  This problem is exposed by LTP inotify06 testcase on
some machines.

We fix the problem by making sure all group marks are properly freed
while destroying inotify instance.  We wait for SRCU period to end in
that path anyway since we have to make sure there is no event being
added to the instance while we are tearing down the instance.  So it
takes only some plumbing to allow for marks to be destroyed in that path
as well and not from a dedicated work item.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NJan Kara <jack@suse.cz>
Reported-by: NXiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Tested-by: NXiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull tracing updates from Steven Rostedt:
 "This includes two new updates for the ftrace infrastructure.

   - With the changing of the code for filtering events by pid, from a
     list of pids to a bitmask, we can now easily implement following
     forks.  With a new tracing option "event-fork" which, when set,
     will have tasks with pids in set_event_pid, when they fork, to have
     their child pids added to set_event_pid and the child will be
     traced as well.

     Note, if "event-fork" is set and a task with its pid in
     set_event_pid exits, its pid will be removed from set_event_pid

   - The addition of Tom Zanussi's hist triggers.  This includes a very
     thorough documentatino on how to use the hist triggers with events.
     This introduces a quick and easy way to get histogram data from
     events and their fields.

  Some other cleanups and updates were added as well.  Like Masami
  Hiramatsu added test cases for the event trigger and hist triggers.
  Also I added a speed up of filtering by using a temp buffer when
  filters are set"

* tag 'trace-v4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (45 commits)
  tracing: Use temp buffer when filtering events
  tracing: Remove TRACE_EVENT_FL_USE_CALL_FILTER logic
  tracing: Remove unused function trace_current_buffer_lock_reserve()
  tracing: Remove one use of trace_current_buffer_lock_reserve()
  tracing: Have trace_buffer_unlock_commit() call the _regs version with NULL
  tracing: Remove unused function trace_current_buffer_discard_commit()
  tracing: Move trace_buffer_unlock_commit{_regs}() to local header
  tracing: Fold filter_check_discard() into its only user
  tracing: Make filter_check_discard() local
  tracing: Move event_trigger_unlock_commit{_regs}() to local header
  tracing: Don't use the address of the buffer array name in copy_from_user
  tracing: Handle tracing_map_alloc_elts() error path correctly
  tracing: Add check for NULL event field when creating hist field
  tracing: checking for NULL instead of IS_ERR()
  tracing: Do not inherit event-fork option for instances
  tracing: Fix unsigned comparison to zero in hist trigger code
  kselftests/ftrace: Add a test for log2 modifier of hist trigger
  tracing: Add hist trigger 'log2' modifier
  kselftests/ftrace: Add hist trigger testcases
  kselftests/ftrace : Add event trigger testcases
  ...

Pull audit updates from Paul Moore:
 "Four small audit patches for 4.7.

  Two are simple cleanups around the audit thread management code, one
  adds a tty field to AUDIT_LOGIN events, and the final patch makes
  tty_name() usable regardless of CONFIG_TTY.

  Nothing controversial, and it all passes our regression test"

* 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit:
  tty: provide tty_name() even without CONFIG_TTY
  audit: add tty field to LOGIN event
  audit: we don't need to __set_current_state(TASK_RUNNING)
  audit: cleanup prune_tree_thread