1 files changed, 37 insertions, 4 deletions

diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
index aef22ae2af47..6d6cb7a57bb3 100644
--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -35,11 +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_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)			\
@@ -58,8 +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)
@@ -79,6 +81,10 @@ SETPCGFLAG(FileMapped, FILE_MAPPED)
 CLEARPCGFLAG(FileMapped, FILE_MAPPED)
 TESTPCGFLAG(FileMapped, FILE_MAPPED)
 
+SETPCGFLAG(Migration, MIGRATION)
+CLEARPCGFLAG(Migration, MIGRATION)
+TESTPCGFLAG(Migration, MIGRATION)
+
 static inline int page_cgroup_nid(struct page_cgroup *pc)
 {
 	return page_to_nid(pc->page);
@@ -91,6 +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);
 }
 
@@ -99,6 +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;