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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 2608AC43461 for ; Fri, 4 Sep 2020 16:21:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E34B32067C for ; Fri, 4 Sep 2020 16:21:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726369AbgIDQVr (ORCPT ); Fri, 4 Sep 2020 12:21:47 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:59304 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726184AbgIDQVl (ORCPT ); Fri, 4 Sep 2020 12:21:41 -0400 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-218-rbseevaSOzmvEljWHFsisw-1; Fri, 04 Sep 2020 12:21:36 -0400 X-MC-Unique: rbseevaSOzmvEljWHFsisw-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 6AE1F189E621; Fri, 4 Sep 2020 16:21:34 +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 E453E7E40A; Fri, 4 Sep 2020 16:21:30 +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 084GLUdx030258; Fri, 4 Sep 2020 12:21:30 -0400 Received: from localhost (mpatocka@localhost) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4/Submit) with ESMTP id 084GLTGx030254; Fri, 4 Sep 2020 12:21:29 -0400 X-Authentication-Warning: file01.intranet.prod.int.rdu2.redhat.com: mpatocka owned process doing -bs Date: Fri, 4 Sep 2020 12:21:29 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Linus Torvalds cc: Jann Horn , Christoph Hellwig , Oleg Nesterov , Kirill Shutemov , Jan Kara , "Theodore Ts'o" , Andrea Arcangeli , Matthew Wilcox , Andrew Morton , Dan Williams , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-ext4@vger.kernel.org Subject: make misbehavior on ext2 in dax mode (was: a crash when running strace from persistent memory) 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 On Thu, 3 Sep 2020, Mikulas Patocka wrote: > Hi > > There's a bug when you run strace from dax-based filesystem. Hmm, so I've found another bug in dax mode. If you extract the Linux kernel tree on dax-based ext2 filesystem (use the real ext2 driver, not ext4), and then you run make twice, the second invocation will rebuild everything. It seems like a problem with timestamps. mount -t ext2 -o dax /dev/pmem0 /mnt/ext2/ cd /mnt/ext2/usr/src/git/linux-2.6 make clean make -j12 make -j12 <--- this rebuilds the whole tree, althought it shouldn't I wasn't able to bisect it because this bug seems to be present in every kernel I tried (back to 4.16.0). Ext4 doesn't seem to have this bug. Mikulas