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Vladimir Davydov 959c8963fc memcg, slab: fix barrier usage when accessing memcg_caches 
Each root kmem_cache has pointers to per-memcg caches stored in its
memcg_params::memcg_caches array.  Whenever we want to allocate a slab
for a memcg, we access this array to get per-memcg cache to allocate
from (see memcg_kmem_get_cache()).  The access must be lock-free for
performance reasons, so we should use barriers to assert the kmem_cache
is up-to-date.

First, we should place a write barrier immediately before setting the
pointer to it in the memcg_caches array in order to make sure nobody
will see a partially initialized object.  Second, we should issue a read
barrier before dereferencing the pointer to conform to the write
barrier.

However, currently the barrier usage looks rather strange.  We have a
write barrier *after* setting the pointer and a read barrier *before*
reading the pointer, which is incorrect.  This patch fixes this.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@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>
 		2014-01-23 16:36:51 -08:00
..
Kconfig mm: add missing dependency in Kconfig 2013-12-18 19:04:52 -08:00
Kconfig.debug
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Makefile
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backing-dev.c
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balloon_compaction.c mm: print more details for bad_page() 2014-01-23 16:36:50 -08:00
bootmem.c mm/bootmem.c: remove unused local `map' 2013-11-13 12:09:09 +09:00
bounce.c mm/bounce.c: fix a regression where MS_SNAP_STABLE (stable pages snapshotting) was ignored 2013-09-30 14:31:02 -07:00
cleancache.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
compaction.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
debug-pagealloc.c
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dmapool.c
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fadvise.c
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failslab.c
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filemap.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
filemap_xip.c seqcount: Add lockdep functionality to seqcount/seqlock structures 2013-11-06 12:40:26 +01:00
fremap.c mm: fix use-after-free in sys_remap_file_pages 2014-01-02 14:40:30 -08:00
frontswap.c
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highmem.c
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huge_memory.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
hugetlb.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
hugetlb_cgroup.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
hwpoison-inject.c mm/hwpoison: add '#' to hwpoison_inject 2014-01-21 16:19:48 -08:00
init-mm.c
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internal.h mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
interval_tree.c
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kmemcheck.c
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kmemleak-test.c
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kmemleak.c mm: kmemleak: avoid false negatives on vmalloc'ed objects 2013-11-13 12:09:07 +09:00
ksm.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
list_lru.c mm: list_lru: fix almost infinite loop causing effective livelock 2013-10-30 12:57:46 -07:00
maccess.c
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madvise.c mm/hwpoison: fix traversal of hugetlbfs pages to avoid printk flood 2013-09-30 14:31:02 -07:00
memblock.c mm/memblock: use WARN_ONCE when MAX_NUMNODES passed as input parameter 2014-01-21 16:19:48 -08:00
memcontrol.c memcg, slab: fix barrier usage when accessing memcg_caches 2014-01-23 16:36:51 -08:00
memory-failure.c mm/migrate: remove putback_lru_pages, fix comment on putback_movable_pages 2014-01-21 16:19:49 -08:00
memory.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
memory_hotplug.c mm: print more details for bad_page() 2014-01-23 16:36:50 -08:00
mempolicy.c mm/mempolicy: fix !vma in new_vma_page() 2013-12-18 19:04:52 -08:00
mempool.c
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migrate.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
mincore.c
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mlock.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
mm_init.c mm: numa: Change page last {nid,pid} into {cpu,pid} 2013-10-09 14:47:45 +02:00
mmap.c mm/mmap.c: add mlock_future_check() helper 2014-01-21 16:19:44 -08:00
mmu_context.c
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mmu_notifier.c
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mmzone.c mm: numa: Change page last {nid,pid} into {cpu,pid} 2013-10-09 14:47:45 +02:00
mprotect.c mm: numa: do not automatically migrate KSM pages 2014-01-21 16:19:48 -08:00
mremap.c mm: revert mremap pud_free anti-fix 2013-10-16 21:35:53 -07:00
msync.c
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nobootmem.c mm/memblock: switch to use NUMA_NO_NODE instead of MAX_NUMNODES 2014-01-21 16:19:46 -08:00
nommu.c mm: add overcommit_kbytes sysctl variable 2014-01-21 16:19:44 -08:00
oom_kill.c oom_kill: add rcu_read_lock() into find_lock_task_mm() 2014-01-21 16:19:46 -08:00
page-writeback.c writeback: fix negative bdi max pause 2013-10-16 21:35:53 -07:00
page_alloc.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
page_cgroup.c Merge branch 'akpm' (incoming from Andrew) 2014-01-21 19:05:45 -08:00
page_io.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
page_isolation.c
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pagewalk.c mm/pagewalk.c: fix walk_page_range() access of wrong PTEs 2013-10-30 14:27:03 -07:00
percpu-km.c
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percpu-vm.c
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percpu.c Merge branch 'akpm' (incoming from Andrew) 2014-01-21 19:05:45 -08:00
pgtable-generic.c mm: fix TLB flush race between migration, and change_protection_range 2013-12-18 19:04:51 -08:00
process_vm_access.c
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quicklist.c
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readahead.c readahead: fix sequential read cache miss detection 2013-11-13 12:09:09 +09:00
rmap.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
shmem.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
slab.c Merge branch 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux 2013-11-22 08:10:34 -08:00
slab.h memcg, slab: fix barrier usage when accessing memcg_caches 2014-01-23 16:36:51 -08:00
slab_common.c memcg, slab: clean up memcg cache initialization/destruction 2014-01-23 16:36:51 -08:00
slob.c
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slub.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
sparse-vmemmap.c mm/sparse: use memblock apis for early memory allocations 2014-01-21 16:19:47 -08:00
sparse.c mm/sparse: use memblock apis for early memory allocations 2014-01-21 16:19:47 -08:00
swap.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
swap_state.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
swapfile.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
truncate.c truncate: drop 'oldsize' truncate_pagecache() parameter 2013-09-12 15:38:02 -07:00
util.c mm: add overcommit_kbytes sysctl variable 2014-01-21 16:19:44 -08:00
vmalloc.c mm/vmalloc: interchage the implementation of vmalloc_to_{pfn,page} 2014-01-21 16:19:44 -08:00
vmpressure.c memcg: make cgroup_event deal with mem_cgroup instead of cgroup_subsys_state 2013-11-22 18:20:43 -05:00
vmscan.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
vmstat.c mm: numa: return the number of base pages altered by protection changes 2013-11-13 12:09:11 +09:00
zbud.c
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zswap.c mm/zswap.c: change params from hidden to ro 2014-01-23 16:36:50 -08:00