Commit 3168ecbe authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds

mm: memcg: use proper memcg in limit bypass

Commit 84235de3 ("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: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 12aee278
......@@ -2765,10 +2765,10 @@ done:
*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;
......
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