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Message-Id: <20170525064635.2832-11-ying.huang@intel.com>
Date: Thu, 25 May 2017 14:46:32 +0800
From: "Huang, Ying" <ying.huang@...el.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Huang Ying <ying.huang@...el.com>,
Johannes Weiner <hannes@...xchg.org>,
Minchan Kim <minchan@...nel.org>,
Michal Hocko <mhocko@...nel.org>,
Andrea Arcangeli <aarcange@...hat.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH -mm 10/13] memcg, THP, swap: Avoid to duplicated charge THP in swap cache
From: Huang Ying <ying.huang@...el.com>
For a THP (Transparent Huge Page), tail_page->mem_cgroup is NULL. So
to check whether the page is charged already, we need to check the
head page. This is not an issue before because it is impossible for a
THP to be in the swap cache before. But after we add delaying
splitting THP after swapped out support, it is possible now.
Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Minchan Kim <minchan@...nel.org>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
---
mm/memcontrol.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1f36bb61a6de..7de1fa07f77d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5372,7 +5372,7 @@ int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
* in turn serializes uncharging.
*/
VM_BUG_ON_PAGE(!PageLocked(page), page);
- if (page->mem_cgroup)
+ if (compound_head(page)->mem_cgroup)
goto out;
if (do_swap_account) {
--
2.11.0
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