memcg: page_cgroup array is never stored on reserved pages

KAMEZAWA Hiroyuki noted that free_pages_cgroup doesn't have to check for
PageReserved because we never store the array on reserved pages (neither
alloc_pages_exact nor vmalloc use those pages).

So we can replace the check by a BUG_ON.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 5 deletions

diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index 8e7577cdf5e4..a12cc3fa9859 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -153,11 +153,11 @@ static void free_page_cgroup(void *addr)
                 vfree(addr);
         } else {
                 struct page *page = virt_to_page(addr);
-                if (!PageReserved(page)) { /* Is bootmem ? */
-                        size_t table_size =
-                                sizeof(struct page_cgroup) * PAGES_PER_SECTION;
-                        free_pages_exact(addr, table_size);
-                }
+                size_t table_size =
+                        sizeof(struct page_cgroup) * PAGES_PER_SECTION;
+
+                BUG_ON(PageReserved(page));
+                free_pages_exact(addr, table_size);
         }
 }
 #endif