slab: do not panic if we fail to create memcg cache

There is no point in flooding logs with warnings or especially crashing
the system if we fail to create a cache for a memcg.  In this case we
will be accounting the memcg allocation to the root cgroup until we
succeed to create its own cache, but it isn't that critical.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/mm/slab_common.c b/mm/slab_common.c
index f34707eeacc7..8e40321da091 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -233,7 +233,14 @@ out_unlock:
         mutex_unlock(&slab_mutex);
         put_online_cpus();
 
-        if (err) {
+        /*
+         * There is no point in flooding logs with warnings or especially
+         * crashing the system if we fail to create a cache for a memcg. In
+         * this case we will be accounting the memcg allocation to the root
+         * cgroup until we succeed to create its own cache, but it isn't that
+         * critical.
+         */
+        if (err && !memcg) {
                 if (flags & SLAB_PANIC)
                         panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
                                 name, err);