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authorVladimir Davydov <vdavydov.dev@gmail.com>2016-12-13 03:41:32 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-13 05:55:06 +0300
commit89e364db71fb5e7fc8d93228152abfa67daf35fa (patch)
tree7e70cba61d27fc6e7c7ebd21ec498b808ba2e132 /mm/slab_common.c
parent13583c3d3224508582ec03d881d0b68dd3ee8e10 (diff)
downloadlinux-89e364db71fb5e7fc8d93228152abfa67daf35fa.tar.xz
slub: move synchronize_sched out of slab_mutex on shrink
synchronize_sched() is a heavy operation and calling it per each cache owned by a memory cgroup being destroyed may take quite some time. What is worse, it's currently called under the slab_mutex, stalling all works doing cache creation/destruction. Actually, there isn't much point in calling synchronize_sched() for each cache - it's enough to call it just once - after setting cpu_partial for all caches and before shrinking them. This way, we can also move it out of the slab_mutex, which we have to hold for iterating over the slab cache list. Link: https://bugzilla.kernel.org/show_bug.cgi?id=172991 Link: http://lkml.kernel.org/r/0a10d71ecae3db00fb4421bcd3f82bcc911f4be4.1475329751.git.vdavydov.dev@gmail.com Signed-off-by: Vladimir Davydov <vdavydov.dev@gmail.com> Reported-by: Doug Smythies <dsmythies@telus.net> Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> 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 'mm/slab_common.c')
-rw-r--r--mm/slab_common.c27
1 files changed, 25 insertions, 2 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 329b03843863..5d2f24fbafc5 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -573,6 +573,29 @@ void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
get_online_cpus();
get_online_mems();
+#ifdef CONFIG_SLUB
+ /*
+ * In case of SLUB, we need to disable empty slab caching to
+ * avoid pinning the offline memory cgroup by freeable kmem
+ * pages charged to it. SLAB doesn't need this, as it
+ * periodically purges unused slabs.
+ */
+ mutex_lock(&slab_mutex);
+ list_for_each_entry(s, &slab_caches, list) {
+ c = is_root_cache(s) ? cache_from_memcg_idx(s, idx) : NULL;
+ if (c) {
+ c->cpu_partial = 0;
+ c->min_partial = 0;
+ }
+ }
+ mutex_unlock(&slab_mutex);
+ /*
+ * kmem_cache->cpu_partial is checked locklessly (see
+ * put_cpu_partial()). Make sure the change is visible.
+ */
+ synchronize_sched();
+#endif
+
mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_caches, list) {
if (!is_root_cache(s))
@@ -584,7 +607,7 @@ void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
if (!c)
continue;
- __kmem_cache_shrink(c, true);
+ __kmem_cache_shrink(c);
arr->entries[idx] = NULL;
}
mutex_unlock(&slab_mutex);
@@ -755,7 +778,7 @@ int kmem_cache_shrink(struct kmem_cache *cachep)
get_online_cpus();
get_online_mems();
kasan_cache_shrink(cachep);
- ret = __kmem_cache_shrink(cachep, false);
+ ret = __kmem_cache_shrink(cachep);
put_online_mems();
put_online_cpus();
return ret;