slub: fix memcg_propagate_slab_attrs

After creating a cache for a memcg we should initialize its sysfs attrs
with the values from its parent.  That's what memcg_propagate_slab_attrs
is for.  Currently it's broken - we clearly muddled root-vs-memcg caches
there.  Let's fix it up.

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

diff --git a/mm/slub.c b/mm/slub.c
index 5e234f1f8853e952dceefe8c6b92201fcc3853d7..042a47b4d0f53e93ca63bc9a7ec443ae1708f119 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5071,15 +5071,18 @@ static void memcg_propagate_slab_attrs(struct kmem_cache *s)
 #ifdef CONFIG_MEMCG_KMEM
        int i;
        char *buffer = NULL;
+       struct kmem_cache *root_cache;
 
-       if (!is_root_cache(s))
+       if (is_root_cache(s))
                return;
 
+       root_cache = s->memcg_params->root_cache;
+
        /*
         * This mean this cache had no attribute written. Therefore, no point
         * in copying default values around
         */
-       if (!s->max_attr_size)
+       if (!root_cache->max_attr_size)
                return;
 
        for (i = 0; i < ARRAY_SIZE(slab_attrs); i++) {
@@ -5101,7 +5104,7 @@ static void memcg_propagate_slab_attrs(struct kmem_cache *s)
                 */
                if (buffer)
                        buf = buffer;
-               else if (s->max_attr_size < ARRAY_SIZE(mbuf))
+               else if (root_cache->max_attr_size < ARRAY_SIZE(mbuf))
                        buf = mbuf;
                else {
                        buffer = (char *) get_zeroed_page(GFP_KERNEL);
@@ -5110,7 +5113,7 @@ static void memcg_propagate_slab_attrs(struct kmem_cache *s)
                        buf = buffer;
                }
 
-               attr->show(s->memcg_params->root_cache, buf);
+               attr->show(root_cache, buf);
                attr->store(s, buf, strlen(buf));
        }