From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754126AbbILHeY (ORCPT ); Sat, 12 Sep 2015 03:34:24 -0400 Received: from mail.kernel.org ([198.145.29.136]:51550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751015AbbILHeX (ORCPT ); Sat, 12 Sep 2015 03:34:23 -0400 Message-ID: <1442043259.21347.4.camel@hasee> Subject: Re: 32-bit bio regression with 4.3 [was: Re: cgroup/loop Bad page state oops in Linux v4.2-rc3-136-g45b4b782e848] From: Ming Lin To: Mike Snitzer Cc: Josh Boyer , Joe Thornber , Ming Lei , Johannes Weiner , Tejun Heo , Jens Axboe , "Linux-Kernel@Vger. Kernel. Org" , awilliam@redhat.com Date: Sat, 12 Sep 2015 00:34:19 -0700 In-Reply-To: References: <20150731001907.GB10250@redhat.com> <20150803142822.GA10657@redhat.com> <20150911214315.GA26995@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2015-09-11 at 21:43 -0700, Ming Lin wrote: > On Fri, Sep 11, 2015 at 2:43 PM, Mike Snitzer wrote: > > Ming, Jens, others: > > > > Please see this BZ comment that speaks to a 4.3 regression due to the > > late bio splitting changes: > > https://bugzilla.redhat.com/show_bug.cgi?id=1247382#c41 > > > > But inlined here so we can continue on list: > > (In reply to Josh Boyer from comment #40) > >> The function that was fixed in 4.2 doesn't exist any longer in > >> 4.3.0-0.rc0.git6.1.fc24. That kernel corresponds to Linux > >> v4.2-6105-gdd5cdb48edfd which contains commit > >> 8ae126660fddbeebb9251a174e6fa45b6ad8f932, which removed it completely. So > >> whatever fix was made in dm_merge_bvec doesn't seem to have made it to > >> whatever replaced it. > > > > The dm core fix to dm_merge_bvec was commit bd4aaf8f9b ("dm: fix > > dm_merge_bvec regression on 32 bit systems"). But I'm not sure there is > > a clear equivalent in the late bio splitting code that replaced block > > core's merge_bvec logic. > > > > merge_bvec was all about limiting bios (by asking "can/should this page > > be added to this bio?") whereas the late bio splitting is more "build > > the bios as large as possible and worry about splitting later". > > > > Regardless, this regression needs to be reported to Ming Lin > > , Jens Axboe and the others involved in > > maintaining the late bio splitting changes in block core. > > I'm looking at it now. I tried rawhide-20150903 boot.iso and rawhide-20150904 boot.iso. 0903 boot.iso is OK, but 0904 boot.iso just stuck at "Reached target Basic System". So I can't see the panic. http://www.minggr.net/pub/20150912/rawhide-20150904-boot.iso.png I'll run test on 32bit VM, see if I can reproduce the bug. Adam, Could you also help to confirm that commit 7140aaf is OK and commit 8ae1266 is bad? Thanks, Ming