summaryrefslogtreecommitdiffstats
path: root/include
diff options
context:
space:
mode:
authorJoonsoo Kim <js1304@gmail.com>2012-09-17 14:09:09 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-09-17 15:00:38 -0700
commit8ba00bb68a067c221cc3ea3a0293e8fcbdcb7ba1 (patch)
tree6642f9819b79c51891d7f829c5cf1f384ffc6cc5 /include
parentd014dc2ed4fae84cb92509416c8bfc9078d4f0d9 (diff)
downloadlinux-8ba00bb68a067c221cc3ea3a0293e8fcbdcb7ba1.tar.bz2
slub: consider pfmemalloc_match() in get_partial_node()
get_partial() is currently not checking pfmemalloc_match() meaning that it is possible for pfmemalloc pages to leak to non-pfmemalloc users. This is a problem in the following situation. Assume that there is a request from normal allocation and there are no objects in the per-cpu cache and no node-partial slab. In this case, slab_alloc enters the slow path and new_slab_objects() is called which may return a PFMEMALLOC page. As the current user is not allowed to access PFMEMALLOC page, deactivate_slab() is called ([5091b74a: mm: slub: optimise the SLUB fast path to avoid pfmemalloc checks]) and returns an object from PFMEMALLOC page. Next time, when we get another request from normal allocation, slab_alloc() enters the slow-path and calls new_slab_objects(). In new_slab_objects(), we call get_partial() and get a partial slab which was just deactivated but is a pfmemalloc page. We extract one object from it and re-deactivate. "deactivate -> re-get in get_partial -> re-deactivate" occures repeatedly. As a result, access to PFMEMALLOC page is not properly restricted and it can cause a performance degradation due to frequent deactivation. deactivation frequently. This patch changes get_partial_node() to take pfmemalloc_match() into account and prevents the "deactivate -> re-get in get_partial() scenario. Instead, new_slab() is called. Signed-off-by: Joonsoo Kim <js1304@gmail.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
0 files changed, 0 insertions, 0 deletions