From 89e364db71fb5e7fc8d93228152abfa67daf35fa Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Mon, 12 Dec 2016 16:41:32 -0800 Subject: 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 Reported-by: Doug Smythies Acked-by: Joonsoo Kim Cc: Christoph Lameter Cc: David Rientjes Cc: Johannes Weiner Cc: Michal Hocko Cc: Pekka Enberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slub.c | 19 ++----------------- 1 file changed, 2 insertions(+), 17 deletions(-) (limited to 'mm/slub.c') diff --git a/mm/slub.c b/mm/slub.c index 2b3e740609e9..4a861f265cd7 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3883,7 +3883,7 @@ EXPORT_SYMBOL(kfree); * being allocated from last increasing the chance that the last objects * are freed in them. */ -int __kmem_cache_shrink(struct kmem_cache *s, bool deactivate) +int __kmem_cache_shrink(struct kmem_cache *s) { int node; int i; @@ -3895,21 +3895,6 @@ int __kmem_cache_shrink(struct kmem_cache *s, bool deactivate) unsigned long flags; int ret = 0; - if (deactivate) { - /* - * Disable empty slabs caching. Used to avoid pinning offline - * memory cgroups by kmem pages that can be freed. - */ - s->cpu_partial = 0; - s->min_partial = 0; - - /* - * s->cpu_partial is checked locklessly (see put_cpu_partial), - * so we have to make sure the change is visible. - */ - synchronize_sched(); - } - flush_all(s); for_each_kmem_cache_node(s, node, n) { INIT_LIST_HEAD(&discard); @@ -3966,7 +3951,7 @@ static int slab_mem_going_offline_callback(void *arg) mutex_lock(&slab_mutex); list_for_each_entry(s, &slab_caches, list) - __kmem_cache_shrink(s, false); + __kmem_cache_shrink(s); mutex_unlock(&slab_mutex); return 0; -- cgit v1.2.3-59-g8ed1b