1 files changed, 33 insertions, 5 deletions

diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
index 5bb13b3db84d..6d6cb7a57bb3 100644
--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -35,12 +35,15 @@ struct page_cgroup *lookup_page_cgroup(struct page *page);
 
 enum {
         /* flags for mem_cgroup */
-        PCG_LOCK,  /* page cgroup is locked */
+        PCG_LOCK,  /* Lock for pc->mem_cgroup and following bits. */
         PCG_CACHE, /* charged as cache */
         PCG_USED, /* this object is in use. */
-        PCG_ACCT_LRU, /* page has been accounted for */
-        PCG_FILE_MAPPED, /* page is accounted as "mapped" */
         PCG_MIGRATION, /* under page migration */
+        /* flags for mem_cgroup and file and I/O status */
+        PCG_MOVE_LOCK, /* For race between move_account v.s. following bits */
+        PCG_FILE_MAPPED, /* page is accounted as "mapped" */
+        /* No lock in page_cgroup */
+        PCG_ACCT_LRU, /* page has been accounted for (under lru_lock) */
 };
 
 #define TESTPCGFLAG(uname, lname)                       \
@@ -59,8 +62,6 @@ static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
 static inline int TestClearPageCgroup##uname(struct page_cgroup *pc)    \
         { return test_and_clear_bit(PCG_##lname, &pc->flags);  }
 
-TESTPCGFLAG(Locked, LOCK)
-
 /* Cache flag is set only once (at allocation) */
 TESTPCGFLAG(Cache, CACHE)
 CLEARPCGFLAG(Cache, CACHE)
@@ -96,6 +97,10 @@ static inline enum zone_type page_cgroup_zid(struct page_cgroup *pc)
 
 static inline void lock_page_cgroup(struct page_cgroup *pc)
 {
+        /*
+         * Don't take this lock in IRQ context.
+         * This lock is for pc->mem_cgroup, USED, CACHE, MIGRATION
+         */
         bit_spin_lock(PCG_LOCK, &pc->flags);
 }
 
@@ -104,6 +109,29 @@ 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)
+{
+        /*
+         * We know updates to pc->flags of page cache's stats are from both of
+         * usual context or IRQ context. Disable IRQ to avoid deadlock.
+         */
+        local_irq_save(*flags);
+        bit_spin_lock(PCG_MOVE_LOCK, &pc->flags);
+}
+
+static inline void move_unlock_page_cgroup(struct page_cgroup *pc,
+        unsigned long *flags)
+{
+        bit_spin_unlock(PCG_MOVE_LOCK, &pc->flags);
+        local_irq_restore(*flags);
+}
+
 #else /* CONFIG_CGROUP_MEM_RES_CTLR */
 struct page_cgroup;