[patch 3/3] mm: move page->mem_cgroup bad page handling into generic code

[Johannes Weiner <hannes@cmpxchg.org>]

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>
---
 include/linux/memcontrol.h |  4 ----
 mm/debug.c                 |  5 ++++-
 mm/memcontrol.c            | 15 ---------------
 mm/page_alloc.c            | 12 ++++++++----
 4 files changed, 12 insertions(+), 24 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index dafba59b31b4..e789551d4db0 100644
--- a/include/linux/memcontrol.h
+++ b/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;
 
diff --git a/mm/debug.c b/mm/debug.c
index 5ce45c9a29b5..0e58f3211f89 100644
--- a/mm/debug.c
+++ b/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)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index fbb41a170eae..3645641513a1 100644
--- a/mm/memcontrol.c
+++ b/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,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6a952237a677..161da09fcda2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -653,8 +653,10 @@ 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;
@@ -920,8 +922,10 @@ 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;
-- 
2.1.3

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