From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753757AbdFWHPB (ORCPT ); Fri, 23 Jun 2017 03:15:01 -0400 Received: from mga02.intel.com ([134.134.136.20]:52134 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753551AbdFWHO4 (ORCPT ); Fri, 23 Jun 2017 03:14:56 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.39,376,1493708400"; d="scan'208";a="116565886" From: "Huang, Ying" To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ross Zwisler , linux-nvdimm@lists.01.org, Huang Ying , Johannes Weiner , Minchan Kim , Michal Hocko , Andrea Arcangeli , "Kirill A . Shutemov" Subject: [PATCH -mm -v2 09/12] memcg, THP, swap: Avoid to duplicated charge THP in swap cache Date: Fri, 23 Jun 2017 15:13:00 +0800 Message-Id: <20170623071303.13469-10-ying.huang@intel.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170623071303.13469-1-ying.huang@intel.com> References: <20170623071303.13469-1-ying.huang@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 99e96ae59cd3..123564bcdd77 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) { -- 2.11.0