From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ph.de-nserver.de ([85.158.179.214]:12862 "EHLO mail-ph.de-nserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751064AbbIKEzk (ORCPT ); Fri, 11 Sep 2015 00:55:40 -0400 Subject: Re: btrfs regression since 4.X kernel NULL pointer dereference To: Jeff Mahoney , Chris Mason , Christoph Hellwig , "linux-btrfs@vger.kernel.org" , "" , linux-kernel.bfrz@manchmal.in-ulm.de References: <55D8B193.8010906@profihost.ag> <20150825090030.GF31630@lst.de> <20150825135146.GE7176@ret.masoncoding.com> <590FB3C7-8BCA-4B04-BBB0-92863E02A89C@profihost.ag> <20150901000610.GC5136@ret.masoncoding.com> <55F20276.1050209@suse.com> From: Stefan Priebe Message-ID: <55F25ED1.3060107@profihost.ag> Date: Fri, 11 Sep 2015 06:55:45 +0200 MIME-Version: 1.0 In-Reply-To: <55F20276.1050209@suse.com> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Am 11.09.2015 um 00:21 schrieb Jeff Mahoney: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 8/31/15 8:06 PM, Chris Mason wrote: >> On Mon, Aug 31, 2015 at 07:32:09PM +0200, Stefan Priebe - >> Profihost AG wrote: >>>> Am 25.08.2015 um 15:51 schrieb Chris Mason : >>>> >>>>> On Tue, Aug 25, 2015 at 11:00:30AM +0200, Christoph Hellwig >>>>> wrote: I think this is btrfs using a struct block_device >>>>> that doesn't have a valid queue pointer in it's gendisk for >>>>> ->s_bdev. And there are some fishy looking ->s_bdev >>>>> assignments in the code which I suspect are related to it: >>>>> >>>>> fs/btrfs/dev-replace.c: if (fs_info->sb->s_bdev == >>>>> src_device->bdev) fs/btrfs/dev-replace.c: fs_info->sb->s_bdev >>>>> = tgt_device->bdev; fs/btrfs/volumes.c: if (device->bdev == >>>>> root->fs_info->sb->s_bdev) fs/btrfs/volumes.c: >>>>> root->fs_info->sb->s_bdev = next_device->bdev; >>>>> fs/btrfs/volumes.c: if (tgtdev->bdev == >>>>> fs_info->sb->s_bdev) fs/btrfs/volumes.c: fs_info->sb->s_bdev >>>>> = next_device->bdev; >>>> >>>> We've had trouble with this in the past, I'll take a look. >>> >>> Any news? >> >> Haven't been able to reproduce yet, I'll try again in the morning. > > I'm unable to reproduce it as well and I'm hearing about people > hitting it in different forums. > > Can you describe your storage configuration? There's a gendisk > without a queue sneaking in somehow. There are some spots in dm where > the mddev gets a new queue assigned to it but the old queue associated > with the gendisk is left behind so that's not it. I'm hitting this inside a debian buil VM using schroot. So the disk is a simple plain qemu emulated scsi disk (virtio-pci-scsi). > If you're able to > reproduce it reliably with this configuration, that's certainly > interesting. I'm wondering if the case is that vgcfgbackup is > iterating over devices and causing something that might not have been > previously scanned to be scanned and added to the btrfs device list. I'm not the guy from the kernel bug report - so i'm only using debian schroot not vgcfgbackup. I can trigger it 100% by using schroot with sbuild using debian or ubuntu. > Are there any messages above the oops indicating when a device is > added? Could you post your complete dmesg somewhere? Sure: http://pastebin.com/raw.php?i=bG6bZUPA Thanks! Greets, Stefan > Thanks, > > - -Jeff > > - -- > Jeff Mahoney > SUSE Labs > -----BEGIN PGP SIGNATURE----- > Version: GnuPG/MacGPG2 v2.0.19 (Darwin) > > iQIcBAEBAgAGBQJV8gJ2AAoJEB57S2MheeWyEP4QALvIXZGIqkXhUBZEYvLC+rnD > Q79chLpbt8x52xtFoav78i3nG24SMXV5NbhFlGNnr6xt/CQtKSzBuDyJ+nigkyy+ > bTtHbwkMqNddrqKJ3r928nKwz1IOyU4J58l7hGyC0owSA3mDxyI7+yS16OXFwc1S > 6lxtV4ljf6nqobA+rVyC3n3BU6CF1aL45V2FpM/m4OHL/Xqv97Xg2tGlysnk8RPD > dRvz5fs2T75B0eBsK4xWHKEgKKWdVYaKqlySRXUJQpnNJTlJltW5HzL8RnR47brt > LLaOCD4jcLlEtGhTi6wEN6BlEYbgDx/1yjQs5zxLG0vbTUi5ZcTeT82d5+Hh4WMD > HyLfE4pwFUZXTHvcIoQ51wPLS/tWMVJXnleQKBrDT+WcsKPr5yuwUZpwfrOBfjol > Qan13/mIcmvFsz2yVWnoZJWU5osnhe+frBsVFlIFLNXp50QVXk+WvruPDOsoY2eQ > J8L20LhY5e0dgJseXWkAAy68mJ0/rrkX0iAdiED/WEsBdjy7QuOomJqPyQQEPplm > d+tIkDR77Biajket2tNEXK1m14f7QvFUFojI0NwegcmZT3iJ7BBWD6wjxIvh3KqE > LqHIcTaECU9XSg9x9E3N416hCbclC9xeosxaJB1iN+EvpaD7CBA+V+onkNMN6Fu4 > J0aVUYlZuLcqkEs/BuNL > =BRtR > -----END PGP SIGNATURE----- >