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-rw-r--r--mm/memcontrol.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e2996b8..b665127 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -358,6 +358,10 @@ void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
return;
pc = lookup_page_cgroup(page);
+ /*
+ * Used bit is set without atomic ops but after smp_wmb().
+ * For making pc->mem_cgroup visible, insert smp_rmb() here.
+ */
smp_rmb();
/* unused page is not rotated. */
if (!PageCgroupUsed(pc))
@@ -374,7 +378,10 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
if (mem_cgroup_disabled())
return;
pc = lookup_page_cgroup(page);
- /* barrier to sync with "charge" */
+ /*
+ * Used bit is set without atomic ops but after smp_wmb().
+ * For making pc->mem_cgroup visible, insert smp_rmb() here.
+ */
smp_rmb();
if (!PageCgroupUsed(pc))
return;
@@ -559,6 +566,14 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
return NULL;
pc = lookup_page_cgroup(page);
+ /*
+ * Used bit is set without atomic ops but after smp_wmb().
+ * For making pc->mem_cgroup visible, insert smp_rmb() here.
+ */
+ smp_rmb();
+ if (!PageCgroupUsed(pc))
+ return NULL;
+
mz = page_cgroup_zoneinfo(pc);
if (!mz)
return NULL;
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