From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1AAECECDFB8 for ; Mon, 23 Jul 2018 12:32:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA2D620854 for ; Mon, 23 Jul 2018 12:32:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CA2D620854 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389698AbeGWNdH (ORCPT ); Mon, 23 Jul 2018 09:33:07 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:46608 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389188AbeGWNdH (ORCPT ); Mon, 23 Jul 2018 09:33:07 -0400 Received: from localhost (LFbn-1-12238-233.w90-92.abo.wanadoo.fr [90.92.53.233]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 935ECBD4; Mon, 23 Jul 2018 12:32:07 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hugh Dickins , Ashwin Chaugule , Yang Shi , "Kirill A. Shutemov" , "Huang, Ying" , Andrew Morton , Linus Torvalds Subject: [PATCH 4.9 10/28] mm/huge_memory.c: fix data loss when splitting a file pmd Date: Mon, 23 Jul 2018 14:25:10 +0200 Message-Id: <20180723122425.896982316@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180723122425.241418073@linuxfoundation.org> References: <20180723122425.241418073@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hugh Dickins commit e1f1b1572e8db87a56609fd05bef76f98f0e456a upstream. __split_huge_pmd_locked() must check if the cleared huge pmd was dirty, and propagate that to PageDirty: otherwise, data may be lost when a huge tmpfs page is modified then split then reclaimed. How has this taken so long to be noticed? Because there was no problem when the huge page is written by a write system call (shmem_write_end() calls set_page_dirty()), nor when the page is allocated for a write fault (fault_dirty_shared_page() calls set_page_dirty()); but when allocated for a read fault (which MAP_POPULATE simulates), no set_page_dirty(). Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1807111741430.1106@eggly.anvils Fixes: d21b9e57c74c ("thp: handle file pages in split_huge_pmd()") Signed-off-by: Hugh Dickins Reported-by: Ashwin Chaugule Reviewed-by: Yang Shi Reviewed-by: Kirill A. Shutemov Cc: "Huang, Ying" Cc: [4.8+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/huge_memory.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1642,6 +1642,8 @@ static void __split_huge_pmd_locked(stru if (vma_is_dax(vma)) return; page = pmd_page(_pmd); + if (!PageDirty(page) && pmd_dirty(_pmd)) + set_page_dirty(page); if (!PageReferenced(page) && pmd_young(_pmd)) SetPageReferenced(page); page_remove_rmap(page, true);