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-rw-r--r--mm/memcontrol.c62
1 files changed, 42 insertions, 20 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8afed2819b8f..df1e180f6c30 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1910,32 +1910,59 @@ bool mem_cgroup_handle_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
* If there is, we take a lock.
*/
+void __mem_cgroup_begin_update_page_stat(struct page *page,
+ bool *locked, unsigned long *flags)
+{
+ struct mem_cgroup *memcg;
+ struct page_cgroup *pc;
+
+ pc = lookup_page_cgroup(page);
+again:
+ memcg = pc->mem_cgroup;
+ if (unlikely(!memcg || !PageCgroupUsed(pc)))
+ return;
+ /*
+ * If this memory cgroup is not under account moving, we don't
+ * need to take move_lock_page_cgroup(). Because we already hold
+ * rcu_read_lock(), any calls to move_account will be delayed until
+ * rcu_read_unlock() if mem_cgroup_stealed() == true.
+ */
+ if (!mem_cgroup_stealed(memcg))
+ return;
+
+ move_lock_mem_cgroup(memcg, flags);
+ if (memcg != pc->mem_cgroup || !PageCgroupUsed(pc)) {
+ move_unlock_mem_cgroup(memcg, flags);
+ goto again;
+ }
+ *locked = true;
+}
+
+void __mem_cgroup_end_update_page_stat(struct page *page, unsigned long *flags)
+{
+ struct page_cgroup *pc = lookup_page_cgroup(page);
+
+ /*
+ * It's guaranteed that pc->mem_cgroup never changes while
+ * lock is held because a routine modifies pc->mem_cgroup
+ * should take move_lock_page_cgroup().
+ */
+ move_unlock_mem_cgroup(pc->mem_cgroup, flags);
+}
+
void mem_cgroup_update_page_stat(struct page *page,
enum mem_cgroup_page_stat_item idx, int val)
{
struct mem_cgroup *memcg;
struct page_cgroup *pc = lookup_page_cgroup(page);
- bool need_unlock = false;
unsigned long uninitialized_var(flags);
if (mem_cgroup_disabled())
return;
-again:
- rcu_read_lock();
+
memcg = pc->mem_cgroup;
if (unlikely(!memcg || !PageCgroupUsed(pc)))
- goto out;
- /* pc->mem_cgroup is unstable ? */
- if (unlikely(mem_cgroup_stealed(memcg))) {
- /* take a lock against to access pc->mem_cgroup */
- move_lock_mem_cgroup(memcg, &flags);
- if (memcg != pc->mem_cgroup || !PageCgroupUsed(pc)) {
- move_unlock_mem_cgroup(memcg, &flags);
- rcu_read_unlock();
- goto again;
- }
- need_unlock = true;
- }
+ return;
switch (idx) {
case MEMCG_NR_FILE_MAPPED:
@@ -1950,11 +1977,6 @@ again:
}
this_cpu_add(memcg->stat->count[idx], val);
-
-out:
- if (unlikely(need_unlock))
- move_unlock_mem_cgroup(memcg, &flags);
- rcu_read_unlock();
}
/*