mm, slab: memcg_link the SLAB's kmem_cache

[ Upstream commit 880cd276dff17ea29e9a8404275c9502b265afa7 ]

All the root caches are linked into slab_root_caches which was
introduced by the commit 510ded33e075 ("slab: implement slab_root_caches
list") but it missed to add the SLAB's kmem_cache.

While experimenting with opt-in/opt-out kmem accounting, I noticed
system crashes due to NULL dereference inside cache_from_memcg_idx()
while deferencing kmem_cache.memcg_params.memcg_caches.  The upstream
clean kernel will not see these crashes but SLAB should be consistent
with SLUB which does linked its boot caches (kmem_cache_node and
kmem_cache) into slab_root_caches.

Link: http://lkml.kernel.org/r/20180319210020.60289-1-shakeelb@google.com
Fixes: 510ded33e075c ("slab: implement slab_root_caches list")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/slab.c b/mm/slab.c
index 1bfc3d847a0a552a3db8a028ceddfa52340a3388..198c1e2c5358589a3f1242668f5341afe3c7dc43 100644 (file)
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1283,6 +1283,7 @@ void __init kmem_cache_init(void)
                                  nr_node_ids * sizeof(struct kmem_cache_node *),
                                  SLAB_HWCACHE_ALIGN);
        list_add(&kmem_cache->list, &slab_caches);
+       memcg_link_cache(kmem_cache);
        slab_state = PARTIAL;
 
        /*