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authorVladimir Davydov <vdavydov@parallels.com>2014-12-13 03:58:25 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-13 23:42:53 +0300
commit061d7074e1eb4e663058e70d409a3cc00634232d (patch)
treed6945513189808ad91cf4bb064d432438abe7484
parent07a46ed27dc6344de831a450df82336270a157a9 (diff)
downloadlinux-061d7074e1eb4e663058e70d409a3cc00634232d.tar.xz
slab: fix cpuset check in fallback_alloc
fallback_alloc is called on kmalloc if the preferred node doesn't have free or partial slabs and there's no pages on the node's free list (GFP_THISNODE allocations fail). Before invoking the reclaimer it tries to locate a free or partial slab on other allowed nodes' lists. While iterating over the preferred node's zonelist it skips those zones which hardwall cpuset check returns false for. That means that for a task bound to a specific node using cpusets fallback_alloc will always ignore free slabs on other nodes and go directly to the reclaimer, which, however, may allocate from other nodes if cpuset.mem_hardwall is unset (default). As a result, we may get lists of free slabs grow without bounds on other nodes, which is bad, because inactive slabs are only evicted by cache_reap at a very slow rate and cannot be dropped forcefully. To reproduce the issue, run a process that will walk over a directory tree with lots of files inside a cpuset bound to a node that constantly experiences memory pressure. Look at num_slabs vs active_slabs growth as reported by /proc/slabinfo. To avoid this we should use softwall cpuset check in fallback_alloc. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Zefan Li <lizefan@huawei.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/slab.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/slab.c b/mm/slab.c
index 6042fe57cc60..65b5dcb6f671 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3015,7 +3015,7 @@ retry:
for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
nid = zone_to_nid(zone);
- if (cpuset_zone_allowed(zone, flags | __GFP_HARDWALL) &&
+ if (cpuset_zone_allowed(zone, flags) &&
get_node(cache, nid) &&
get_node(cache, nid)->free_objects) {
obj = ____cache_alloc_node(cache,