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mm: memcg: use proper memcg in limit bypass

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Commit 84235de394 ("fs: buffer: move allocation failure loop into the
allocator") allowed __GFP_NOFAIL allocations to bypass the limit if they
fail to reclaim enough memory for the charge.  But because the main test
case was on a 3.2-based system, the patch missed the fact that on newer
kernels the charge function needs to return root_mem_cgroup when
bypassing the limit, and not NULL.  This will corrupt whatever memory is
at NULL + percpu pointer offset.  Fix this quickly before problems are
reported.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner 2013-10-31 16:34:13 -07:00 committed by Linus Torvalds
parent 12aee278b5
commit 3168ecbe1c
1 changed files with 4 additions and 4 deletions
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8
mm/memcontrol.c
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@ -2765,10 +2765,10 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
*ptr = memcg;
return 0;
nomem:
*ptr = NULL;
if (gfp_mask & __GFP_NOFAIL)
return 0;
return -ENOMEM;
if (!(gfp_mask & __GFP_NOFAIL)) {
*ptr = NULL;
return -ENOMEM;
}
bypass:
*ptr = root_mem_cgroup;
return -EINTR;