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-rw-r--r--include/linux/page_cgroup.h31
-rw-r--r--mm/memcontrol.c9
2 files changed, 35 insertions, 5 deletions
diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
index fdb5a92b5ac7..5b0c971d7cae 100644
--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -35,15 +35,18 @@ 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" */
PCG_FILE_DIRTY, /* page is dirty */
PCG_FILE_WRITEBACK, /* page is under writeback */
PCG_FILE_UNSTABLE_NFS, /* page is NFS unstable */
- PCG_MIGRATION, /* under page migration */
+ /* No lock in page_cgroup */
+ PCG_ACCT_LRU, /* page has been accounted for (under lru_lock) */
};
#define TESTPCGFLAG(uname, lname) \
@@ -117,6 +120,10 @@ 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);
}
@@ -130,6 +137,24 @@ 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;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3d8a0c79dece..d888956a2cfc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1606,6 +1606,7 @@ void mem_cgroup_update_page_stat(struct page *page,
struct mem_cgroup *mem;
struct page_cgroup *pc = lookup_page_cgroup(page);
bool need_unlock = false;
+ unsigned long uninitialized_var(flags);
if (unlikely(!pc))
return;
@@ -1617,7 +1618,7 @@ void mem_cgroup_update_page_stat(struct page *page,
/* pc->mem_cgroup is unstable ? */
if (unlikely(mem_cgroup_stealed(mem))) {
/* take a lock against to access pc->mem_cgroup */
- lock_page_cgroup(pc);
+ move_lock_page_cgroup(pc, &flags);
need_unlock = true;
mem = pc->mem_cgroup;
if (!mem || !PageCgroupUsed(pc))
@@ -1640,7 +1641,7 @@ void mem_cgroup_update_page_stat(struct page *page,
out:
if (unlikely(need_unlock))
- unlock_page_cgroup(pc);
+ move_unlock_page_cgroup(pc, &flags);
rcu_read_unlock();
return;
}
@@ -2211,9 +2212,13 @@ static int mem_cgroup_move_account(struct page_cgroup *pc,
struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
{
int ret = -EINVAL;
+ unsigned long flags;
+
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);
+ move_unlock_page_cgroup(pc, &flags);
ret = 0;
}
unlock_page_cgroup(pc);