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Subject[patch 7/8] mm: memcg: modify PageCgroupAcctLRU non-atomically
Date
From: Johannes Weiner <jweiner@redhat.com>

This bit is protected by zone->lru_lock, there is no need for locked
operations when setting and clearing it.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
---
include/linux/page_cgroup.h | 16 ++++++++++++----
mm/memcontrol.c | 4 ++--
2 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
index aaa60da..a0bc9d0 100644
--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -57,14 +57,23 @@ static inline int PageCgroup##uname(struct page_cgroup *pc) \
#define SETPCGFLAG(uname, lname) \
static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
{ set_bit(PCG_##lname, &pc->flags); }
+#define __SETPCGFLAG(uname, lname) \
+static inline void __SetPageCgroup##uname(struct page_cgroup *pc)\
+ { __set_bit(PCG_##lname, &pc->flags); }

#define CLEARPCGFLAG(uname, lname) \
static inline void ClearPageCgroup##uname(struct page_cgroup *pc) \
{ clear_bit(PCG_##lname, &pc->flags); }
+#define __CLEARPCGFLAG(uname, lname) \
+static inline void __ClearPageCgroup##uname(struct page_cgroup *pc) \
+ { __clear_bit(PCG_##lname, &pc->flags); }

#define TESTCLEARPCGFLAG(uname, lname) \
static inline int TestClearPageCgroup##uname(struct page_cgroup *pc) \
{ return test_and_clear_bit(PCG_##lname, &pc->flags); }
+#define __TESTCLEARPCGFLAG(uname, lname) \
+static inline int __TestClearPageCgroup##uname(struct page_cgroup *pc) \
+ { return __test_and_clear_bit(PCG_##lname, &pc->flags); }

/* Cache flag is set only once (at allocation) */
TESTPCGFLAG(Cache, CACHE)
@@ -75,11 +84,10 @@ TESTPCGFLAG(Used, USED)
CLEARPCGFLAG(Used, USED)
SETPCGFLAG(Used, USED)

-SETPCGFLAG(AcctLRU, ACCT_LRU)
-CLEARPCGFLAG(AcctLRU, ACCT_LRU)
+__SETPCGFLAG(AcctLRU, ACCT_LRU)
+__CLEARPCGFLAG(AcctLRU, ACCT_LRU)
TESTPCGFLAG(AcctLRU, ACCT_LRU)
-TESTCLEARPCGFLAG(AcctLRU, ACCT_LRU)
-
+__TESTCLEARPCGFLAG(AcctLRU, ACCT_LRU)

SETPCGFLAG(FileMapped, FILE_MAPPED)
CLEARPCGFLAG(FileMapped, FILE_MAPPED)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b9a3b94..51aba19 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -995,7 +995,7 @@ struct lruvec *mem_cgroup_lru_add_list(struct zone *zone, struct page *page,
/* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
smp_rmb();
memcg = pc->mem_cgroup;
- SetPageCgroupAcctLRU(pc);
+ __SetPageCgroupAcctLRU(pc);
} else
memcg = root_mem_cgroup;
mz = page_cgroup_zoneinfo(memcg, page);
@@ -1031,7 +1031,7 @@ void mem_cgroup_lru_del_list(struct page *page, enum lru_list lru)
* LRU-accounting happened against pc->mem_cgroup or
* root_mem_cgroup.
*/
- if (TestClearPageCgroupAcctLRU(pc)) {
+ if (__TestClearPageCgroupAcctLRU(pc)) {
VM_BUG_ON(!pc->mem_cgroup);
memcg = pc->mem_cgroup;
} else
--
1.7.6.4


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