Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753335AbdGXFUQ (ORCPT ); Mon, 24 Jul 2017 01:20:16 -0400 Received: from mga04.intel.com ([192.55.52.120]:7383 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752862AbdGXFTE (ORCPT ); Mon, 24 Jul 2017 01:19:04 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.40,405,1496127600"; d="scan'208";a="290458746" From: "Huang, Ying" To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , Johannes Weiner , Minchan Kim , Michal Hocko , Andrea Arcangeli , "Kirill A . Shutemov" Subject: [PATCH -mm -v3 09/12] memcg, THP, swap: Avoid to duplicated charge THP in swap cache Date: Mon, 24 Jul 2017 13:18:37 +0800 Message-Id: <20170724051840.2309-10-ying.huang@intel.com> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170724051840.2309-1-ying.huang@intel.com> References: <20170724051840.2309-1-ying.huang@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1146 Lines: 33 From: Huang Ying 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" Cc: Johannes Weiner Cc: Minchan Kim Cc: Michal Hocko Cc: Andrea Arcangeli Cc: "Kirill A . Shutemov" --- mm/memcontrol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c2618bd8ebdd..a627b0fd67ea 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5407,7 +5407,7 @@ 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) { -- 2.13.2