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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 8C76DC432C0 for ; Tue, 19 Nov 2019 10:08:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5C9202230C for ; Tue, 19 Nov 2019 10:08:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=mbobrowski-org.20150623.gappssmtp.com header.i=@mbobrowski-org.20150623.gappssmtp.com header.b="v8Q3Ts5n" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727399AbfKSKIb (ORCPT ); Tue, 19 Nov 2019 05:08:31 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:34523 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726921AbfKSKIb (ORCPT ); Tue, 19 Nov 2019 05:08:31 -0500 Received: by mail-pg1-f196.google.com with SMTP id z188so11145841pgb.1 for ; Tue, 19 Nov 2019 02:08:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mbobrowski-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=0as+kqGp44tyRx+kW5oQfsxwSoGdl6l76oT22Nl8N74=; b=v8Q3Ts5nxlnauS/2ghDpbPKFgU64xhcUk2q9N0EIKCrEeCO1UZzdvm7IxtaY2XYPox DIHxrwKQ1tzXYSKoZY5C7lLdHvwJ4dTI9PGVyravK4EbkP01DQ9DhAzxQZutRDhxYmDT VTY4TDGDSPgqLRcJYHp71FgLyYf6puBT63wzO3s3OClM8A+6XXuYqJd8iwbtvJia0tgj yzx/SQrS4tR5h4Z4vSBYh3CE+03HV2elpZ/6xxadUkDMlG/70b7shQf2rPHa+BzqcXm+ AOeqQ7WXjQUfeoBP1EqMUCsJykbbdHJQHTfVaz4SF0i/z+y/+FeNRd+CCGbvVX78DTwn FZFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=0as+kqGp44tyRx+kW5oQfsxwSoGdl6l76oT22Nl8N74=; b=qe540Uk1Sh+pII60fvIgYdPhOZv5YAaw6vuhNjH3E+FBZO+M8JJj3tieJ2vwu1eWzs 987qBeXDQm77wFJy45MZLoVWuUGyuHnyXvzvYwewBx6LcxBaGuhRB7v6iQ1fk7u7epeX N2AweYhOd080naqpkX6yox0r6T0U+W3dTT3UUKaLA6zjj30RbNkGlT578ZH2HTZMjNHW lcRQ31OP7t5hZyRZ2Nknu4JTGqDvnrppkfVxk8ERATMRAQW2hQvbwDE8e20a/twCxv82 fiIajulMHCFUjYTp2Jk+tCsIoESCFmt2Uktq3v8FveTULCHCOF6EBbSd0A3Qo7Dj4Nri QRcw== X-Gm-Message-State: APjAAAUxMIGIHIkNy5yZ8i3VqnDbw2SJJ7PkEWbZ54kMAu/e39MfqYwX bV+++VsriLl1m1UxvJE/nT8L X-Google-Smtp-Source: APXvYqxOjci1H8Ei4WdF79tc6UVvv6rGHGtq5HEtKINHp8jaqtc8G29vaDRMXLC+T1Tt4lx/p/J5UQ== X-Received: by 2002:a63:5f49:: with SMTP id t70mr4738291pgb.219.1574158110418; Tue, 19 Nov 2019 02:08:30 -0800 (PST) Received: from bobrowski ([110.232.114.101]) by smtp.gmail.com with ESMTPSA id v128sm6167533pgv.24.2019.11.19.02.08.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Nov 2019 02:08:29 -0800 (PST) Date: Tue, 19 Nov 2019 21:08:22 +1100 From: Matthew Bobrowski To: Eric Biggers Cc: Jan Kara , syzbot , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, riteshh@linux.ibm.com, syzkaller-bugs@googlegroups.com, tytso@mit.edu, viro@zeniv.linux.org.uk Subject: Re: WARNING in iov_iter_pipe Message-ID: <20191119100821.GB22484@bobrowski> References: <000000000000d60aa50596c63063@google.com> <20191108103148.GE20863@quack2.suse.cz> <20191111081628.GB14058@bobrowski> <20191119031021.GI3147@sol.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191119031021.GI3147@sol.localdomain> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Nov 18, 2019 at 07:10:21PM -0800, Eric Biggers wrote: > On Mon, Nov 11, 2019 at 07:16:29PM +1100, Matthew Bobrowski wrote: > > On Fri, Nov 08, 2019 at 11:31:48AM +0100, Jan Kara wrote: > > > On Thu 07-11-19 10:54:10, syzbot wrote: > > > > syzbot found the following crash on: > > > > > > > > HEAD commit: c68c5373 Add linux-next specific files for 20191107 > > > > git tree: linux-next > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=13d6bcfce00000 > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=742545dcdea21726 > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=991400e8eba7e00a26e1 > > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1529829ae00000 > > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16a55c0ce00000 > > > > > > > > The bug was bisected to: > > > > > > > > commit b1b4705d54abedfd69dcdf42779c521aa1e0fbd3 > > > > Author: Matthew Bobrowski > > > > Date: Tue Nov 5 12:01:37 2019 +0000 > > > > > > > > ext4: introduce direct I/O read using iomap infrastructure > > > > > > Hum, interesting and from the first looks the problem looks real. > > > Deciphered reproducer is: > > > > > > int fd0 = open("./file0", O_RDWR | O_CREAT | O_EXCL | O_DIRECT, 0); > > > int fd1 = open("./file0, O_RDONLY); > > > write(fd0, "some_data...", 512); > > > sendfile(fd0, fd1, NULL, 0x7fffffa7); > > > -> this is interesting as it will result in reading data from 'file0' at > > > offset X with buffered read and writing them with direct write to > > > offset X+512. So this way we'll grow the file up to those ~2GB in > > > 512-byte chunks. > > > - not sure if we ever get there but the remainder of the reproducer is: > > > fd2 = open("./file0", O_RDWR | O_CREAT | O_NOATIME | O_SYNC, 0); > > > sendfile(fd2, fd0, NULL, 0xffffffff) > > > -> doesn't seem too interesting as fd0 is at EOF so this shouldn't do > > > anything. > > > > > > Matthew, can you have a look? > > > > Sorry Jan, I've been crazy busy lately and I'm out at training this > > week. Let me take a look at this and see whether I can determine > > what's happening here. > > > > FYI, syzbot is still seeing this on linux-next. > > Also, a new thread was started to discuss this: > https://lkml.kernel.org/linux-ext4/20191113180032.GB12013@quack2.suse.cz/T/#u > (Mentioning this in case anyone is following this thread only.) Understood. I suppose this issue will get some more traction this week. /M