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Vladimir Davydov 6df38689e0 mm: memcontrol: fix possible memcg leak due to interrupted reclaim 
Memory cgroup reclaim can be interrupted with mem_cgroup_iter_break()
once enough pages have been reclaimed, in which case, in contrast to a
full round-trip over a cgroup sub-tree, the current position stored in
mem_cgroup_reclaim_iter of the target cgroup does not get invalidated
and so is left holding the reference to the last scanned cgroup.  If the
target cgroup does not get scanned again (we might have just reclaimed
the last page or all processes might exit and free their memory
voluntary), we will leak it, because there is nobody to put the
reference held by the iterator.

The problem is easy to reproduce by running the following command
sequence in a loop:

    mkdir /sys/fs/cgroup/memory/test
    echo 100M > /sys/fs/cgroup/memory/test/memory.limit_in_bytes
    echo $$ > /sys/fs/cgroup/memory/test/cgroup.procs
    memhog 150M
    echo $$ > /sys/fs/cgroup/memory/cgroup.procs
    rmdir test

The cgroups generated by it will never get freed.

This patch fixes this issue by making mem_cgroup_iter avoid taking
reference to the current position.  In order not to hit use-after-free
bug while running reclaim in parallel with cgroup deletion, we make use
of ->css_released cgroup callback to clear references to the dying
cgroup in all reclaim iterators that might refer to it.  This callback
is called right before scheduling rcu work which will free css, so if we
access iter->position from rcu read section, we might be sure it won't
go away under us.

[hannes@cmpxchg.org: clean up css ref handling]
Fixes: 5ac8fb31ad ("mm: memcontrol: convert reclaim iterator to simple css refcounting")
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>	[3.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-29 17:45:49 -08:00
..
kasan kasan: fix kmemleak false-positive in kasan_module_alloc() 2015-11-20 16:17:32 -08:00
backing-dev.c mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress 2015-12-12 10:15:34 -08:00
balloon_compaction.c mm: page migration trylock newpage at same level as oldpage 2015-11-05 19:34:48 -08:00
bootmem.c bootmem: avoid freeing to bootmem after bootmem is done 2015-09-08 15:35:28 -07:00
cleancache.c cleancache: remove limit on the number of cleancache enabled filesystems 2015-04-14 16:49:03 -07:00
cma.c mm/cma.c: suppress warning 2015-11-05 19:34:48 -08:00
cma.h mm: cma: mark cma_bitmap_maxno() inline in header 2015-08-14 15:56:32 -07:00
cma_debug.c mm/cma_debug: correct size input to bitmap function 2015-07-17 16:39:54 -07:00
compaction.c mm, compaction: distinguish contended status in tracepoints 2015-11-05 19:34:48 -08:00
debug-pagealloc.c mm/debug-pagealloc: make debug-pagealloc boottime configurable 2014-12-13 12:42:48 -08:00
debug.c mm: make compound_head() robust 2015-11-06 17:50:42 -08:00
dmapool.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
early_ioremap.c mm/early_ioremap: use offset_in_page macro 2015-11-05 19:34:48 -08:00
fadvise.c writeback: implement and use inode_congested() 2015-06-02 08:33:35 -06:00
failslab.c mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM 2015-11-06 17:50:42 -08:00
filemap.c mm, fs: introduce mapping_gfp_constraint() 2015-11-06 17:50:42 -08:00
frame_vector.c mm: fix docbook comment for get_vaddr_frames() 2015-11-05 19:34:48 -08:00
frontswap.c frontswap: allow multiple backends 2015-06-24 17:49:45 -07:00
gup.c mm: introduce VM_LOCKONFAULT 2015-11-05 19:34:48 -08:00
highmem.c mm/highmem: make kmap cache coloring aware 2014-08-06 18:01:22 -07:00
huge_memory.c mm: loosen MADV_NOHUGEPAGE to enable Qemu postcopy on s390 2015-11-20 16:17:32 -08:00
hugetlb.c mm/hugetlb.c: fix resv map memory leak for placeholder entries 2015-12-12 10:15:34 -08:00
hugetlb_cgroup.c mm: make compound_head() robust 2015-11-06 17:50:42 -08:00
hwpoison-inject.c hwpoison: use page_cgroup_ino for filtering by memcg 2015-09-10 13:29:01 -07:00
init-mm.c
internal.h mm: use 'unsigned int' for page order 2015-11-06 17:50:42 -08:00
interval_tree.c mm: replace vma->sharead.linear with vma->shared 2015-02-10 14:30:31 -08:00
Kconfig mm: make compound_head() robust 2015-11-06 17:50:42 -08:00
Kconfig.debug mm/debug_pagealloc: remove obsolete Kconfig options 2015-01-08 15:10:52 -08:00
kmemcheck.c mm/slab_common: move kmem_cache definition to internal header 2014-10-09 22:25:50 -04:00
kmemleak-test.c mm/kmemleak-test.c: use pr_fmt for logging 2014-06-06 16:08:18 -07:00
kmemleak.c mm/kmemleak.c: remove unneeded initialization of object to NULL 2015-11-05 19:34:48 -08:00
ksm.c ksm: unstable_tree_search_insert error checking cleanup 2015-11-05 19:34:48 -08:00
list_lru.c memcg: simplify and inline __mem_cgroup_from_kmem 2015-11-05 19:34:48 -08:00
maccess.c mm/maccess.c: actually return -EFAULT from strncpy_from_unsafe 2015-11-05 19:34:48 -08:00
madvise.c mm: madvise allow remove operation for hugetlbfs 2015-09-08 15:35:28 -07:00
Makefile media updates for v4.3-rc1 2015-09-11 16:42:39 -07:00
memblock.c mm/memblock: make memblock_remove_range() static 2015-11-05 19:34:48 -08:00
memcontrol.c mm: memcontrol: fix possible memcg leak due to interrupted reclaim 2015-12-29 17:45:49 -08:00
memory-failure.c mm: make compound_head() robust 2015-11-06 17:50:42 -08:00
memory.c mm, dax: fix DAX deadlocks (COW fault) 2015-11-18 16:54:36 -08:00
memory_hotplug.c mm/page_alloc: remove unused parameter in init_currently_empty_zone() 2015-11-05 19:34:48 -08:00
mempolicy.c mm: rename alloc_pages_exact_node() to __alloc_pages_node() 2015-09-08 15:35:28 -07:00
mempool.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
memtest.c memtest: remove unused header files 2015-09-08 15:35:28 -07:00
migrate.c mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM 2015-11-06 17:50:42 -08:00
mincore.c mm/mincore: use offset_in_page macro 2015-11-05 19:34:48 -08:00
mlock.c mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage 2015-11-05 19:34:48 -08:00
mm_init.c mm: meminit: remove mminit_verify_page_links 2015-06-30 19:44:56 -07:00
mmap.c mm: introduce VM_LOCKONFAULT 2015-11-05 19:34:48 -08:00
mmu_context.c sched/mm: call finish_arch_post_lock_switch in idle_task_exit and use_mm 2014-02-21 08:50:17 +01:00
mmu_notifier.c mmu-notifier: add clear_young callback 2015-09-10 13:29:01 -07:00
mmzone.c mm: microoptimize zonelist operations 2015-02-11 17:06:02 -08:00
mprotect.c userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx 2015-09-04 16:54:41 -07:00
mremap.c mm/mremap: use offset_in_page macro 2015-11-05 19:34:48 -08:00
msync.c mm/msync: use offset_in_page macro 2015-11-05 19:34:48 -08:00
nobootmem.c mm: page_alloc: pass PFN to __free_pages_bootmem 2015-06-30 19:44:55 -07:00
nommu.c mm/nommu.c: drop unlikely inside BUG_ON() 2015-11-05 19:34:48 -08:00
oom_kill.c mm/oom_kill.c: avoid attempting to kill init sharing same memory 2015-12-12 10:15:34 -08:00
page-writeback.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
page_alloc.c mm: fix swapped Movable and Reclaimable in /proc/pagetypeinfo 2015-12-12 10:15:34 -08:00
page_counter.c mm: page_counter: let page_counter_try_charge() return bool 2015-11-05 19:34:48 -08:00
page_ext.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
page_idle.c mm: introduce idle page tracking 2015-09-10 13:29:01 -07:00
page_io.c fs: use helper bio_add_page() instead of open coding on bi_io_vec 2015-08-13 12:32:00 -06:00
page_isolation.c mm, page_isolation: make set/unset_migratetype_isolate() file-local 2015-09-08 15:35:28 -07:00
page_owner.c mm/page_owner: set correct gfp_mask on page_owner 2015-07-17 16:39:54 -07:00
pagewalk.c mm/pagewalk.c: prevent positive return value of walk_page_test() from being passed to callers 2015-03-25 16:20:30 -07:00
percpu-km.c percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated 2014-09-02 14:46:05 -04:00
percpu-vm.c percpu: move region iterations out of pcpu_[de]populate_chunk() 2014-09-02 14:46:02 -04:00
percpu.c mm/percpu: use offset_in_page macro 2015-11-05 19:34:48 -08:00
pgtable-generic.c mm,thp: introduce flush_pmd_tlb_range 2015-10-17 17:48:20 +05:30
process_vm_access.c process_vm_access: switch to {compat_,}import_iovec() 2015-04-11 22:27:12 -04:00
quicklist.c
readahead.c mm, fs: introduce mapping_gfp_constraint() 2015-11-06 17:50:42 -08:00
rmap.c mm: page migration use migration entry for swapcache too 2015-11-05 19:34:48 -08:00
shmem.c tmpfs: fix shmem_evict_inode() warnings on i_blocks 2015-12-12 10:15:34 -08:00
slab.c slab/slub: adjust kmem_cache_alloc_bulk API 2015-11-22 11:58:44 -08:00
slab.h slab/slub: adjust kmem_cache_alloc_bulk API 2015-11-22 11:58:44 -08:00
slab_common.c slab/slub: adjust kmem_cache_alloc_bulk API 2015-11-22 11:58:44 -08:00
slob.c slab/slub: adjust kmem_cache_alloc_bulk API 2015-11-22 11:58:44 -08:00
slub.c slab/slub: adjust kmem_cache_alloc_bulk API 2015-11-22 11:58:44 -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: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:35:54 -07:00
swap.c mm: make compound_head() robust 2015-11-06 17:50:42 -08:00
swap_cgroup.c mm: page_cgroup: rename file to mm/swap_cgroup.c 2014-12-10 17:41:09 -08:00
swap_state.c mm: swap: zswap: maybe_preload & refactoring 2015-09-08 15:35:28 -07:00
swapfile.c mm: /proc/pid/smaps:: show proportional swap share of the mapping 2015-09-08 15:35:28 -07:00
truncate.c memcg: add per cgroup dirty page accounting 2015-06-02 08:33:33 -06:00
userfaultfd.c userfaultfd: avoid mmap_sem read recursion in mcopy_atomic 2015-09-04 16:54:41 -07:00
util.c mm/util: use offset_in_page macro 2015-11-05 19:34:48 -08:00
vmacache.c mm/vmacache: inline vmacache_valid_mm() 2015-11-05 19:34:48 -08:00
vmalloc.c mm: vmalloc: don't remove inexistent guard hole in remove_vm_area() 2015-11-20 16:17:32 -08:00
vmpressure.c mm/vmpressure.c: fix race in vmpressure_work_fn() 2014-12-02 17:32:07 -08:00
vmscan.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
vmstat.c mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress 2015-12-12 10:15:34 -08:00
workingset.c list_lru: add helpers to isolate items 2015-02-12 18:54:10 -08:00
zbud.c mm: zsmalloc: constify struct zs_pool name 2015-11-06 17:50:42 -08:00
zpool.c mm: zsmalloc: constify struct zs_pool name 2015-11-06 17:50:42 -08:00
zsmalloc.c zsmalloc: use page->private instead of page->first_page 2015-11-06 17:50:42 -08:00
zswap.c mm/zswap: change incorrect strncmp use to strcmp 2015-12-18 14:25:40 -08:00