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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 BDB07C3A589 for ; Wed, 21 Aug 2019 00:27:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9702922CF7 for ; Wed, 21 Aug 2019 00:27:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726257AbfHUA1w (ORCPT ); Tue, 20 Aug 2019 20:27:52 -0400 Received: from mail104.syd.optusnet.com.au ([211.29.132.246]:40315 "EHLO mail104.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726028AbfHUA1v (ORCPT ); Tue, 20 Aug 2019 20:27:51 -0400 Received: from dread.disaster.area (pa49-195-190-67.pa.nsw.optusnet.com.au [49.195.190.67]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id 58B4343E0D7; Wed, 21 Aug 2019 10:27:50 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92) (envelope-from ) id 1i0ESZ-0001vi-DY; Wed, 21 Aug 2019 10:26:43 +1000 Date: Wed, 21 Aug 2019 10:26:43 +1000 From: Dave Chinner To: "hch@lst.de" Cc: "Verma, Vishal L" , "linux-xfs@vger.kernel.org" , "Williams, Dan J" , "darrick.wong@oracle.com" Subject: Re: 5.3-rc1 regression with XFS log recovery Message-ID: <20190821002643.GK1119@dread.disaster.area> References: <20190818071128.GA17286@lst.de> <20190818074140.GA18648@lst.de> <20190818173426.GA32311@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190818173426.GA32311@lst.de> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.2 cv=D+Q3ErZj c=1 sm=1 tr=0 a=TR82T6zjGmBjdfWdGgpkDw==:117 a=TR82T6zjGmBjdfWdGgpkDw==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=FmdZ9Uzk2mMA:10 a=7-415B0cAAAA:8 a=rg55TvFzVAOYHM5hWT0A:9 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Sun, Aug 18, 2019 at 07:34:26PM +0200, hch@lst.de wrote: > On Sun, Aug 18, 2019 at 09:41:40AM +0200, hch@lst.de wrote: > > On Sun, Aug 18, 2019 at 09:11:28AM +0200, hch@lst.de wrote: > > > > The kernel log shows the following when the mount fails: > > > > > > Is it always that same message? I'll see if I can reproduce it, > > > but I won't have that much memory to spare to create fake pmem, > > > hope this also works with a single device and/or less memory.. > > > > I've reproduced a similar ASSERT with a small pmem device, so I hope > > I can debug the issue locally now. > > So I can also reproduce the same issue with the ramdisk driver, but not > with any other 4k sector size device (nvmet, scsi target, scsi_debug, > loop). Which made me wonder if there is some issue about the memory > passed in, and indeed just switching to plain vmalloc vs the XFS > kmem_alloc_large wrapper that either uses kmalloc or vmalloc fixes > the issue for me. I don't really understand why yet, maybe I need to > dig out alignment testing patches. > > diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c > index 13d1d3e95b88..918ad3b884a7 100644 > --- a/fs/xfs/xfs_log_recover.c > +++ b/fs/xfs/xfs_log_recover.c > @@ -125,7 +125,7 @@ xlog_alloc_buffer( > if (nbblks > 1 && log->l_sectBBsize > 1) > nbblks += log->l_sectBBsize; > nbblks = round_up(nbblks, log->l_sectBBsize); > - return kmem_alloc_large(BBTOB(nbblks), KM_MAYFAIL); > + return vmalloc(BBTOB(nbblks)); > } After thinking on this for a bit, I suspect the better thing to do here is add a KM_ALIGNED flag to the allocation, so if the internal kmem_alloc() returns an unaligned pointer we free it and fall through to vmalloc() to get a properly aligned pointer.... That way none of the other interfaces have to change, and we can then use kmem_alloc_large() everywhere we allocate buffers for IO. And we don't need new infrastructure just to support these debug configurations, either. Actually, kmem_alloc_io() might be a better idea - keep the aligned flag internal to the kmem code. Seems like a pretty simple solution to the entire problem we have here... Cheers, Dave. -- Dave Chinner david@fromorbit.com