mm: move page->mem_cgroup bad page handling into generic code

Now that the external page_cgroup data structure and its lookup is
gone, let the generic bad_page() check for page->mem_cgroup sanity.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Tejun Heo <tj@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/memcontrol.h

@@ -173,10 +173,6 @@ static inline void mem_cgroup_count_vm_event(struct mm_struct *mm,
 void mem_cgroup_split_huge_fixup(struct page *head);
 #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_MEMCG */
 struct mem_cgroup;
 
@@ -346,19 +342,6 @@ void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
 }
 #endif /* CONFIG_MEMCG */
 
-#if !defined(CONFIG_MEMCG) || !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
-
 enum {
 	UNDER_LIMIT,
 	SOFT_LIMIT,

init/Kconfig

@@ -983,18 +983,6 @@ config MEMCG
 	  Provides a memory resource controller that manages both anonymous
 	  memory and page cache. (See Documentation/cgroups/memory.txt)
 
-	  Note that setting this option increases fixed memory overhead
-	  associated with each page of memory in the system. By this,
-	  8(16)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
-	  usage tracking struct at boot. Total amount of this is printed out
-	  at boot.
-
-	  Only enable when you're ok with these trade offs and really
-	  sure you need the memory resource controller. Even when you enable
-	  this, you can set "cgroup_disable=memory" at your boot option to
-	  disable memory resource controller and you can avoid overheads.
-	  (and lose benefits of memory resource controller)
-
 config MEMCG_SWAP
 	bool "Memory Resource Controller Swap Extension"
 	depends on MEMCG && SWAP

mm/debug.c

@@ -95,7 +95,10 @@ void dump_page_badflags(struct page *page, const char *reason,
 		dump_flags(page->flags & badflags,
 				pageflag_names, ARRAY_SIZE(pageflag_names));
 	}
-	mem_cgroup_print_bad_page(page);
+#ifdef CONFIG_MEMCG
+	if (page->mem_cgroup)
+		pr_alert("page->mem_cgroup:%p\n", page->mem_cgroup);
+#endif
 }
 
 void dump_page(struct page *page, const char *reason)

mm/memcontrol.c

@@ -3157,21 +3157,6 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
 }
 #endif
 
-#ifdef CONFIG_DEBUG_VM
-bool mem_cgroup_bad_page_check(struct page *page)
-{
-	if (mem_cgroup_disabled())
-		return false;
-
-	return page->mem_cgroup != NULL;
-}
-
-void mem_cgroup_print_bad_page(struct page *page)
-{
-	pr_alert("page->mem_cgroup:%p\n", page->mem_cgroup);
-}
-#endif
-
 static DEFINE_MUTEX(memcg_limit_mutex);
 
 static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,

mm/page_alloc.c

@@ -640,8 +640,10 @@ static inline int free_pages_check(struct page *page)
 		bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
 		bad_flags = PAGE_FLAGS_CHECK_AT_FREE;
 	}
-	if (unlikely(mem_cgroup_bad_page_check(page)))
-		bad_reason = "cgroup check failed";
+#ifdef CONFIG_MEMCG
+	if (unlikely(page->mem_cgroup))
+		bad_reason = "page still charged to cgroup";
+#endif
 	if (unlikely(bad_reason)) {
 		bad_page(page, bad_reason, bad_flags);
 		return 1;
@@ -900,8 +902,10 @@ static inline int check_new_page(struct page *page)
 		bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag set";
 		bad_flags = PAGE_FLAGS_CHECK_AT_PREP;
 	}
-	if (unlikely(mem_cgroup_bad_page_check(page)))
-		bad_reason = "cgroup check failed";
+#ifdef CONFIG_MEMCG
+	if (unlikely(page->mem_cgroup))
+		bad_reason = "page still charged to cgroup";
+#endif
 	if (unlikely(bad_reason)) {
 		bad_page(page, bad_reason, bad_flags);
 		return 1;