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567fb435bb
linux/mm
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Glauber Costa 567fb435bb memcg: fix bad behavior in use_hierarchy file 
I have an application that does the following:

* copy the state of all controllers attached to a hierarchy
* replicate it as a child of the current level.

I would expect writes to the files to mostly succeed, since they are
inheriting sane values from parents.

But that is not the case for use_hierarchy.  If it is set to 0, we succeed
ok.  If we're set to 1, the value of the file is automatically set to 1 in
the children, but if userspace tries to write the very same 1, it will
fail.  That same situation happens if we set use_hierarchy, create a
child, and then try to write 1 again.

Now, there is no reason whatsoever for failing to write a value that is
already there.  It doesn't even match the comments, that states:

 /* If parent's use_hierarchy is set, we can't make any modifications
  * in the child subtrees...

since we are not changing anything.

So test the new value against the one we're storing, and automatically
return 0 if we're not proposing a change.

Signed-off-by: Glauber Costa <glommer@parallels.com>
Cc: Dhaval Giani <dhaval.giani@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31 18:42:43 -07:00
..
backing-dev.c mm: prepare for removal of obsolete /proc/sys/vm/nr_pdflush_threads 2012-07-31 18:42:40 -07:00
bootmem.c bootmem: make ___alloc_bootmem_node_nopanic() really nopanic 2012-07-17 16:21:29 -07:00
bounce.c bounce: allow use of bounce pool via config option 2012-07-18 16:40:35 -04:00
cleancache.c ->encode_fh() API change 2012-05-29 23:28:33 -04:00
compaction.c mm, thp: abort compaction if migration page cannot be charged to memcg 2012-07-11 16:04:43 -07:00
debug-pagealloc.c mm, x86: Remove debug_pagealloc_enabled 2011-12-06 09:24:07 +01:00
dmapool.c mm: fix implicit stat.h usage in dmapool.c 2011-10-31 09:20:12 -04:00
fadvise.c mm, fadvise: don't return -EINVAL when filesystem cannot implement fadvise() 2012-07-31 18:42:42 -07:00
failslab.c switch debugfs to umode_t 2012-01-03 22:54:56 -05:00
filemap_xip.c fs: introduce inode operation ->update_time 2012-06-01 12:07:25 -04:00
filemap.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-06-01 10:34:35 -07:00
fremap.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
frontswap.c mm/frontswap: cleanup doc and comment error 2012-07-23 11:16:20 -04:00
highmem.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
huge_memory.c mm/memcg: apply add/del_page to lruvec 2012-05-29 16:22:28 -07:00
hugetlb_cgroup.c hugetlb/cgroup: remove exclude and wakeup rmdir calls from migrate 2012-07-31 18:42:41 -07:00
hugetlb.c hugetlb/cgroup: assign the page hugetlb cgroup when we move the page to active list. 2012-07-31 18:42:41 -07:00
hwpoison-inject.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
init-mm.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
internal.h Revert "mm: compaction: handle incorrect MIGRATE_UNMOVABLE type pageblocks" 2012-06-03 20:05:57 -07:00
Kconfig Frontswap provides a "transcendent memory" interface for swap pages. 2012-06-04 12:28:45 -07:00
Kconfig.debug mm: more intensive memory corruption debugging 2012-01-10 16:30:42 -08:00
kmemcheck.c
kmemleak-test.c kmemleak: remove memset by using kzalloc 2011-01-27 18:31:51 +00:00
kmemleak.c kmemleak: Disable early logging when kmemleak is off by default 2012-01-20 16:57:05 +00:00
ksm.c ksm: cleanup: introduce find_mergeable_vma() 2012-03-21 17:54:59 -07:00
maccess.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
madvise.c mm: Hold a file reference in madvise_remove 2012-07-06 10:34:38 -07:00
Makefile memcg: rename config variables 2012-07-31 18:42:43 -07:00
memblock.c mm/memblock.c:memblock_double_array(): cosmetic cleanups 2012-07-31 18:42:41 -07:00
memcontrol.c memcg: fix bad behavior in use_hierarchy file 2012-07-31 18:42:43 -07:00
memory_hotplug.c mm/memory_hotplug.c: release memory resources if hotadd_new_pgdat() fails 2012-07-11 16:04:46 -07:00
memory-failure.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
memory.c hugetlb: use mmu_gather instead of a temporary linked list for accumulating pages 2012-07-31 18:42:40 -07:00
mempolicy.c Merge branch 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux 2012-07-30 11:32:24 -07:00
mempool.c mempool: fix first round failure behavior 2012-01-10 16:30:45 -08:00
migrate.c hugetlb/cgroup: migrate hugetlb cgroup info from oldpage to new page during migration 2012-07-31 18:42:41 -07:00
mincore.c mm: thp: fix pmd_bad() triggering in code paths holding mmap_sem read mode 2012-03-21 17:54:54 -07:00
mlock.c vm: avoid using find_vma_prev() unnecessarily 2012-03-06 18:23:36 -08:00
mm_init.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
mmap.c mm: account the total_vm in the vm_stat_account() 2012-07-31 18:42:39 -07:00
mmu_context.c mm, counters: remove task argument to sync_mm_rss() and __sync_task_rss_stat() 2012-03-21 17:54:59 -07:00
mmu_notifier.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
mmzone.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
mprotect.c Merge branch 'akpm' (Andrew's patch-bomb) 2012-03-22 09:04:48 -07:00
mremap.c mm: account the total_vm in the vm_stat_account() 2012-07-31 18:42:39 -07:00
msync.c
nobootmem.c memblock: free allocated memblock_reserved_regions later 2012-07-11 16:04:50 -07:00
nommu.c nommu: fix compilation of nommu.c 2012-06-04 17:17:31 -04:00
oom_kill.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
page_alloc.c mm: clean up __count_immobile_pages() 2012-07-31 18:42:42 -07:00
page_cgroup.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
page_io.c frontswap: s/put_page/store/g s/get_page/load 2012-05-15 11:34:08 -04:00
page_isolation.c mm: page_isolation: MIGRATE_CMA isolation functions added 2012-05-21 15:09:33 +02:00
page-writeback.c writeback: Fix some comment errors 2012-06-09 19:54:47 +08:00
pagewalk.c mm: fix kernel-doc warnings 2012-06-20 14:39:36 -07:00
percpu-km.c percpu: clear memory allocated with the km allocator 2010-10-02 10:28:42 +03:00
percpu-vm.c mm: fix kernel-doc warnings 2012-06-20 14:39:36 -07:00
percpu.c kmemleak: Fix the kmemleak tracking of the percpu areas with !SMP 2012-05-09 10:13:29 -07:00
pgtable-generic.c arch/tile: allow building Linux with transparent huge pages enabled 2012-05-25 12:48:21 -04:00
prio_tree.c sanitize <linux/prefetch.h> usage 2011-05-20 12:50:29 -07:00
process_vm_access.c aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector() 2012-05-31 17:49:32 -07:00
quicklist.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
readahead.c mm: move readahead syscall to mm/readahead.c 2012-05-29 16:22:23 -07:00
rmap.c mm: remove swap token code 2012-05-29 16:22:19 -07:00
shmem.c don't pass nameidata to ->create() 2012-07-14 16:34:47 +04:00
slab_common.c mm: Fix build warning in kmem_cache_create() 2012-07-30 13:15:40 +03:00
slab.c mm, sl[aou]b: Move kmem_cache_create mutex handling to common code 2012-07-09 12:13:42 +03:00
slab.h mm, sl[aou]b: Use a common mutex definition 2012-07-09 12:13:41 +03:00
slob.c slob: Fix early boot kernel crash 2012-07-12 10:13:22 +03:00
slub.c mm, slub: ensure irqs are enabled for kmemcheck 2012-07-10 22:43:52 +03:00
sparse-vmemmap.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
sparse.c mm: sparse: fix usemap allocation above node descriptor section 2012-07-11 16:04:49 -07:00
swap_state.c swap: allow swap readahead to be merged 2012-07-31 18:42:39 -07:00
swap.c mm/memcg: apply add/del_page to lruvec 2012-05-29 16:22:28 -07:00
swapfile.c swap: fix shmem swapping when more than 8 areas 2012-06-15 21:48:14 -07:00
truncate.c mm/fs: remove truncate_range 2012-05-29 16:22:23 -07:00
util.c new helper: vm_mmap_pgoff() 2012-06-01 10:37:18 -04:00
vmalloc.c mm: make vb_alloc() more foolproof 2012-07-31 18:42:39 -07:00
vmscan.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
vmstat.c mm/vmstat.c: remove debug fs entries on failure of file creation and made extfrag_debug_root dentry local 2012-05-29 16:22:19 -07:00