diff options
| -rw-r--r-- | mm/memcontrol.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e71e8440de6b..ba9f5404b8cf 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2888,6 +2888,17 @@ struct mem_cgroup *mem_cgroup_from_obj(void *p) page = virt_to_head_page(p); /* + * If page->mem_cgroup is set, it's either a simple mem_cgroup pointer + * or a pointer to obj_cgroup vector. In the latter case the lowest + * bit of the pointer is set. + * The page->mem_cgroup pointer can be asynchronously changed + * from NULL to (obj_cgroup_vec | 0x1UL), but can't be changed + * from a valid memcg pointer to objcg vector or back. + */ + if (!page->mem_cgroup) + return NULL; + + /* * Slab objects are accounted individually, not per-page. * Memcg membership data for each individual object is saved in * the page->obj_cgroups. |