Commit 4ba902b5 authored by Glauber Costa's avatar Glauber Costa Committed by Linus Torvalds

memcg: fix kmemcg registration for late caches

The designed workflow for the caches in kmemcg is: register it with
memcg_register_cache() if kmemcg is already available or later on when a
new kmemcg appears at memcg_update_cache_sizes() which will handle all
caches in the system.  The caches created at boot time will be handled
by the later, and the memcg-caches as well as any system caches that are
registered later on by the former.

There is a bug, however, in memcg_register_cache: we correctly set up
the array size, but do not mark the cache as a root cache.

This means that allocations for any cache appearing late in the game
will see memcg->memcg_params->is_root_cache == false, and in particular,
trigger VM_BUG_ON(!cachep->memcg_params->is_root_cache) in
__memcg_kmem_cache_get.

The obvious fix is to include the missing assignment.
Signed-off-by: default avatarGlauber Costa <glommer@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9977f0f1
...@@ -3030,7 +3030,9 @@ int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s, ...@@ -3030,7 +3030,9 @@ int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s,
if (memcg) { if (memcg) {
s->memcg_params->memcg = memcg; s->memcg_params->memcg = memcg;
s->memcg_params->root_cache = root_cache; s->memcg_params->root_cache = root_cache;
} } else
s->memcg_params->is_root_cache = true;
return 0; return 0;
} }
......
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