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=-8.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 1C846C43461 for ; Sat, 5 Sep 2020 17:05:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C2F4420760 for ; Sat, 5 Sep 2020 17:05:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VVwD2FT7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728451AbgIERFG (ORCPT ); Sat, 5 Sep 2020 13:05:06 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:20213 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728323AbgIERE5 (ORCPT ); Sat, 5 Sep 2020 13:04:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1599325495; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=bBI7if0KCVvWvaBOwMDsnEtZiJjjihsjAtqSgtT6RaA=; b=VVwD2FT7G+kk7Ux2AH6kVQVywMXVhIpucWPtLGf3SeFfBZChFDtjXVaXC5xecCZr8hRDAN TqELawgWqgiaROTilcPx6TOjMHu4iwaF72FMZe426vWeEf6k+B2WF32YR+g0PLblTjU5qf XFvp3hiiXKX5TdjQMmwzMB1sICqeZho= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-286-mgO_poxTNXWtVk_hTdv0qg-1; Sat, 05 Sep 2020 13:04:51 -0400 X-MC-Unique: mgO_poxTNXWtVk_hTdv0qg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 82964185A0F8; Sat, 5 Sep 2020 17:04:49 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (file01.intranet.prod.int.rdu2.redhat.com [10.11.5.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5831F7ED60; Sat, 5 Sep 2020 17:04:46 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (localhost [127.0.0.1]) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4) with ESMTP id 085H4jOV003056; Sat, 5 Sep 2020 13:04:45 -0400 Received: from localhost (mpatocka@localhost) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4/Submit) with ESMTP id 085H4jxR003052; Sat, 5 Sep 2020 13:04:45 -0400 X-Authentication-Warning: file01.intranet.prod.int.rdu2.redhat.com: mpatocka owned process doing -bs Date: Sat, 5 Sep 2020 13:04:45 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: "Darrick J. Wong" cc: Linus Torvalds , Jan Kara , Dave Chinner , Jann Horn , Christoph Hellwig , Oleg Nesterov , Kirill Shutemov , "Theodore Ts'o" , Andrea Arcangeli , Matthew Wilcox , Andrew Morton , Dan Williams , Linux-MM , Linux Kernel Mailing List , linux-nvdimm , Ext4 Developers List , linux-xfs Subject: [PATCH 2/2 v2] xfs: don't update mtime on COW faults In-Reply-To: Message-ID: References: User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When running in a dax mode, if the user maps a page with MAP_PRIVATE and PROT_WRITE, the xfs filesystem would incorrectly update ctime and mtime when the user hits a COW fault. This breaks building of the Linux kernel. How to reproduce: 1. extract the Linux kernel tree on dax-mounted xfs filesystem 2. run make clean 3. run make -j12 4. run make -j12 - at step 4, make would incorrectly rebuild the whole kernel (although it was already built in step 3). The reason for the breakage is that almost all object files depend on objtool. When we run objtool, it takes COW page fault on its .data section, and these faults will incorrectly update the timestamp of the objtool binary. The updated timestamp causes make to rebuild the whole tree. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org --- fs/xfs/xfs_file.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) Index: linux-2.6/fs/xfs/xfs_file.c =================================================================== --- linux-2.6.orig/fs/xfs/xfs_file.c 2020-09-05 18:48:54.000000000 +0200 +++ linux-2.6/fs/xfs/xfs_file.c 2020-09-05 18:56:48.000000000 +0200 @@ -1223,14 +1223,21 @@ __xfs_filemap_fault( return ret; } +static inline bool +xfs_is_shared_dax_write_fault( + struct vm_fault *vmf) +{ + return IS_DAX(file_inode(vmf->vma->vm_file)) && + vmf->flags & FAULT_FLAG_WRITE && vmf->vma->vm_flags & VM_SHARED; +} + static vm_fault_t xfs_filemap_fault( struct vm_fault *vmf) { /* DAX can shortcut the normal fault path on write faults! */ return __xfs_filemap_fault(vmf, PE_SIZE_PTE, - IS_DAX(file_inode(vmf->vma->vm_file)) && - (vmf->flags & FAULT_FLAG_WRITE)); + xfs_is_shared_dax_write_fault(vmf)); } static vm_fault_t @@ -1243,7 +1250,7 @@ xfs_filemap_huge_fault( /* DAX can shortcut the normal fault path on write faults! */ return __xfs_filemap_fault(vmf, pe_size, - (vmf->flags & FAULT_FLAG_WRITE)); + xfs_is_shared_dax_write_fault(vmf)); } static vm_fault_t