From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932100AbbFCGQr (ORCPT ); Wed, 3 Jun 2015 02:16:47 -0400 Received: from lgeamrelo02.lge.com ([156.147.1.126]:56146 "EHLO lgeamrelo02.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752989AbbFCGPs (ORCPT ); Wed, 3 Jun 2015 02:15:48 -0400 X-Original-SENDERIP: 10.177.222.143 X-Original-MAILFROM: minchan@kernel.org From: Minchan Kim To: Andrew Morton Cc: Hugh Dickins , Rik van Riel , Mel Gorman , Michal Hocko , Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Minchan Kim Subject: [RFC 2/6] mm: keep dirty bit on anonymous page migration Date: Wed, 3 Jun 2015 15:15:41 +0900 Message-Id: <1433312145-19386-3-git-send-email-minchan@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1433312145-19386-1-git-send-email-minchan@kernel.org> References: <1433312145-19386-1-git-send-email-minchan@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, If VM migrates anonymous page, we lose dirty bit of page table entry. Instead, VM translates dirty bit of page table as PG_dirty of page flags. It was okay because dirty bit of page table for anonymous page was no matter to swap out. Instead, VM took care of PG_dirty. However, with introducing MADV_FREE, it's important to keep page table's dirty bit because It could make MADV_FREE handling logics more straighforward without taking care of PG_dirty. This patch aims for preparing to remove PG_dirty check for MADV_FREE. Signed-off-by: Minchan Kim --- mm/migrate.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/migrate.c b/mm/migrate.c index 236ee25e79d9..add30c3aaaa9 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -151,6 +151,10 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, if (is_write_migration_entry(entry)) pte = maybe_mkwrite(pte, vma); + /* MADV_FREE relies on pte_dirty. */ + if (PageAnon(new)) + pte = pte_mkdirty(pte); + #ifdef CONFIG_HUGETLB_PAGE if (PageHuge(new)) { pte = pte_mkhuge(pte); -- 1.9.1