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authorVladimir Davydov <vdavydov@parallels.com>2014-04-07 15:39:28 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-07 16:36:13 -0700
commitb8529907ba35d625fa4b85d3e4dc8021be97c1f3 (patch)
tree88ba9609669e3f82b475f7a8bcaa927d5e5928b5 /include/linux/memcontrol.h
parent051dd46050f2a9bdfff8cc067f8987069eae1743 (diff)
memcg, slab: do not destroy children caches if parent has aliases
Currently we destroy children caches at the very beginning of kmem_cache_destroy(). This is wrong, because the root cache will not necessarily be destroyed in the end - if it has aliases (refcount > 0), kmem_cache_destroy() will simply decrement its refcount and return. In this case, at best we will get a bunch of warnings in dmesg, like this one: kmem_cache_destroy kmalloc-32:0: Slab cache still has objects CPU: 1 PID: 7139 Comm: modprobe Tainted: G B W 3.13.0+ #117 Call Trace: dump_stack+0x49/0x5b kmem_cache_destroy+0xdf/0xf0 kmem_cache_destroy_memcg_children+0x97/0xc0 kmem_cache_destroy+0xf/0xf0 xfs_mru_cache_uninit+0x21/0x30 [xfs] exit_xfs_fs+0x2e/0xc44 [xfs] SyS_delete_module+0x198/0x1f0 system_call_fastpath+0x16/0x1b At worst - if kmem_cache_destroy() will race with an allocation from a memcg cache - the kernel will panic. This patch fixes this by moving children caches destruction after the check if the cache has aliases. Plus, it forbids destroying a root cache if it still has children caches, because each children cache keeps a reference to its parent. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Glauber Costa <glommer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/memcontrol.h')
-rw-r--r--include/linux/memcontrol.h6
1 files changed, 1 insertions, 5 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 02d3072841e9..b569b8be5c5a 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -507,7 +507,7 @@ struct kmem_cache *
__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);
void mem_cgroup_destroy_cache(struct kmem_cache *cachep);
-void kmem_cache_destroy_memcg_children(struct kmem_cache *s);
+int __kmem_cache_destroy_memcg_children(struct kmem_cache *s);
/**
* memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
@@ -661,10 +661,6 @@ memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
{
return cachep;
}
-
-static inline void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
-{
-}
#endif /* CONFIG_MEMCG_KMEM */
#endif /* _LINUX_MEMCONTROL_H */