2 files changed, 29 insertions, 42 deletions

diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
index 363bbc8b0f49..6b63679ce8a1 100644
--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -99,11 +99,6 @@ static inline void unlock_page_cgroup(struct page_cgroup *pc)
         bit_spin_unlock(PCG_LOCK, &pc->flags);
 }
 
-static inline int page_is_cgroup_locked(struct page_cgroup *pc)
-{
-        return bit_spin_is_locked(PCG_LOCK, &pc->flags);
-}
-
 static inline void move_lock_page_cgroup(struct page_cgroup *pc,
         unsigned long *flags)
 {
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2881c9ef969a..e9d33dc151a5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2200,33 +2200,49 @@ void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail)
 #endif
 
 /**
- * __mem_cgroup_move_account - move account of the page
+ * mem_cgroup_move_account - move account of the page
  * @pc: page_cgroup of the page.
  * @from: mem_cgroup which the page is moved from.
  * @to: mem_cgroup which the page is moved to. @from != @to.
  * @uncharge: whether we should call uncharge and css_put against @from.
+ * @charge_size: number of bytes to charge (regular or huge page)
  *
  * The caller must confirm following.
  * - page is not on LRU (isolate_page() is useful.)
- * - the pc is locked, used, and ->mem_cgroup points to @from.
+ * - compound_lock is held when charge_size > PAGE_SIZE
  *
  * This function doesn't do "charge" nor css_get to new cgroup. It should be
  * done by a caller(__mem_cgroup_try_charge would be usefull). If @uncharge is
  * true, this function does "uncharge" from old cgroup, but it doesn't if
  * @uncharge is false, so a caller should do "uncharge".
  */
-
-static void __mem_cgroup_move_account(struct page_cgroup *pc,
-        struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge,
-        int charge_size)
+static int mem_cgroup_move_account(struct page_cgroup *pc,
+                                   struct mem_cgroup *from, struct mem_cgroup *to,
+                                   bool uncharge, int charge_size)
 {
         int nr_pages = charge_size >> PAGE_SHIFT;
+        unsigned long flags;
+        int ret;
 
         VM_BUG_ON(from == to);
         VM_BUG_ON(PageLRU(pc->page));
-        VM_BUG_ON(!page_is_cgroup_locked(pc));
-        VM_BUG_ON(!PageCgroupUsed(pc));
-        VM_BUG_ON(pc->mem_cgroup != from);
+        /*
+         * The page is isolated from LRU. So, collapse function
+         * will not handle this page. But page splitting can happen.
+         * Do this check under compound_page_lock(). The caller should
+         * hold it.
+         */
+        ret = -EBUSY;
+        if (charge_size > PAGE_SIZE && !PageTransHuge(pc->page))
+                goto out;
+
+        lock_page_cgroup(pc);
+
+        ret = -EINVAL;
+        if (!PageCgroupUsed(pc) || pc->mem_cgroup != from)
+                goto unlock;
+
+        move_lock_page_cgroup(pc, &flags);
 
         if (PageCgroupFileMapped(pc)) {
                 /* Update mapped_file data for mem_cgroup */
@@ -2250,40 +2266,16 @@ static void __mem_cgroup_move_account(struct page_cgroup *pc,
          * garanteed that "to" is never removed. So, we don't check rmdir
          * status here.
          */
-}
-
-/*
- * check whether the @pc is valid for moving account and call
- * __mem_cgroup_move_account()
- */
-static int mem_cgroup_move_account(struct page_cgroup *pc,
-                struct mem_cgroup *from, struct mem_cgroup *to,
-                bool uncharge, int charge_size)
-{
-        int ret = -EINVAL;
-        unsigned long flags;
-        /*
-         * The page is isolated from LRU. So, collapse function
-         * will not handle this page. But page splitting can happen.
-         * Do this check under compound_page_lock(). The caller should
-         * hold it.
-         */
-        if ((charge_size > PAGE_SIZE) && !PageTransHuge(pc->page))
-                return -EBUSY;
-
-        lock_page_cgroup(pc);
-        if (PageCgroupUsed(pc) && pc->mem_cgroup == from) {
-                move_lock_page_cgroup(pc, &flags);
-                __mem_cgroup_move_account(pc, from, to, uncharge, charge_size);
-                move_unlock_page_cgroup(pc, &flags);
-                ret = 0;
-        }
+        move_unlock_page_cgroup(pc, &flags);
+        ret = 0;
+unlock:
         unlock_page_cgroup(pc);
         /*
          * check events
          */
         memcg_check_events(to, pc->page);
         memcg_check_events(from, pc->page);
+out:
         return ret;
 }