memcg: add memcg sanity checks at allocating and freeing pages

Add checks at allocating or freeing a page whether the page is used (iow,
charged) from the view point of memcg.

This check may be useful in debugging a problem and we did similar checks
before the commit 52d4b9ac(memcg: allocate all page_cgroup at boot).

This patch adds some overheads at allocating or freeing memory, so it's
enabled only when CONFIG_DEBUG_VM is enabled.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 5bb7be2628c..5a5ce705583 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -151,6 +151,10 @@ u64 mem_cgroup_get_limit(struct mem_cgroup *mem);
 void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail);
 #endif
 
+#ifdef CONFIG_DEBUG_VM
+bool mem_cgroup_bad_page_check(struct page *page);
+void mem_cgroup_print_bad_page(struct page *page);
+#endif
 #else /* CONFIG_CGROUP_MEM_RES_CTLR */
 struct mem_cgroup;
 
@@ -352,5 +356,18 @@ static inline void mem_cgroup_split_huge_fixup(struct page *head,
 
 #endif /* CONFIG_CGROUP_MEM_CONT */
 
+#if !defined(CONFIG_CGROUP_MEM_RES_CTLR) || !defined(CONFIG_DEBUG_VM)
+static inline bool
+mem_cgroup_bad_page_check(struct page *page)
+{
+        return false;
+}
+
+static inline void
+mem_cgroup_print_bad_page(struct page *page)
+{
+}
+#endif
+
 #endif /* _LINUX_MEMCONTROL_H */