Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751541AbdIRWBC (ORCPT ); Mon, 18 Sep 2017 18:01:02 -0400 Received: from sandeen.net ([63.231.237.45]:36504 "EHLO sandeen.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750783AbdIRWA7 (ORCPT ); Mon, 18 Sep 2017 18:00:59 -0400 Subject: Re: [linux-next][XFS][trinity] WARNING: CPU: 32 PID: 31369 at fs/iomap.c:993 To: Dave Chinner , Jens Axboe Cc: Christoph Hellwig , Abdul Haleem , linuxppc-dev , linux-xfs , linux-next , linux-kernel , chandan References: <1505746565.6990.18.camel@abdul.in.ibm.com> <20170918152706.GA11482@lst.de> <8abed401-1634-760f-6543-4652fa495315@kernel.dk> <20170918213143.GJ10621@dastard> From: Eric Sandeen Message-ID: <21c53d3f-5ca9-886d-a326-cb6f1bbddffd@sandeen.net> Date: Mon, 18 Sep 2017 17:00:58 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20170918213143.GJ10621@dastard> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1628 Lines: 50 On 9/18/17 4:31 PM, Dave Chinner wrote: > On Mon, Sep 18, 2017 at 09:28:55AM -0600, Jens Axboe wrote: >> On 09/18/2017 09:27 AM, Christoph Hellwig wrote: >>> On Mon, Sep 18, 2017 at 08:26:05PM +0530, Abdul Haleem wrote: >>>> Hi, >>>> >>>> A warning is triggered from: >>>> >>>> file fs/iomap.c in function iomap_dio_rw >>>> >>>> if (ret) >>>> goto out_free_dio; >>>> >>>> ret = invalidate_inode_pages2_range(mapping, >>>> start >> PAGE_SHIFT, end >> PAGE_SHIFT); >>>>>> WARN_ON_ONCE(ret); >>>> ret = 0; >>>> >>>> inode_dio_begin(inode); >>> >>> This is expected and an indication of a problematic workload - which >>> may be triggered by a fuzzer. >> >> If it's expected, why don't we kill the WARN_ON_ONCE()? I get it all >> the time running xfstests as well. > > Because when a user reports a data corruption, the only evidence we > have that they are running an app that does something stupid is this > warning in their syslogs. Tracepoints are not useful for replacing > warnings about data corruption vectors being triggered. Is the full WARN_ON spew really helpful to us, though? Certainly the user has no idea what it means, and will come away terrified but none the wiser. Would a more informative printk_once() still give us the evidence without the ZOMG I THINK I OOPSED that a WARN_ON produces? Or do we want/need the backtrace? -Eric > It needs to be on by default, bu tI'm sure we can wrap it with > something like an xfs_alert_tag() type of construct so the tag can > be set in /proc/fs/xfs/panic_mask to suppress it if testers so > desire. > > Cheers, > > Dave. >