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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 3CCA0C636CA for ; Sat, 17 Jul 2021 23:27:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AF5E3610D1 for ; Sat, 17 Jul 2021 23:27:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AF5E3610D1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B1BD08D00F4; Sat, 17 Jul 2021 19:27:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id ACBA18D00EC; Sat, 17 Jul 2021 19:27:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 993618D00F4; Sat, 17 Jul 2021 19:27:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0239.hostedemail.com [216.40.44.239]) by kanga.kvack.org (Postfix) with ESMTP id 74FA08D00EC for ; Sat, 17 Jul 2021 19:27:27 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 14D5623E5B for ; Sat, 17 Jul 2021 23:27:26 +0000 (UTC) X-FDA: 78373668492.16.F64893C Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf20.hostedemail.com (Postfix) with ESMTP id BBFDBD0000A2 for ; Sat, 17 Jul 2021 23:27:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=4v3mh4cqgqf/BRgKcQOkDQBmxTqX9mmIHLbOgFkhmRI=; b=HArwuRLz83oqtm6OHIUgxDa6Ox euffXP6Isw5SfyruHbx0axyNIt8gS9nlLOnHirhBfwHL8VzvgYeknDT7Wp10yqL/WyIY6JznxsDr0 nt6PySzK7RIj+YmIkFoDd+LCiIcZUUcw/d7FIRn9TxihCDQN31qAQ2Evc4H78V7BohXfYkZcyx63Z NdPwBkzf7I0RpMa+4WCixhNCp2bGF/l7m/BT22Cv9/PJFozYO0kDUS5vuVgxCTwy2MZuTfgAZ7co1 oDr+sUrZhBQON5/nZ82fbyW0En02a/sdbJZTwkz8RpEayePQP0vrOMlU4zs+6MksF6D2Pod7c2aKk FMDiN6CQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1m4th2-005dOY-Aq; Sat, 17 Jul 2021 23:26:13 +0000 Date: Sun, 18 Jul 2021 00:26:00 +0100 From: Matthew Wilcox To: Roman Gushchin Cc: "Darrick J. Wong" , Murphy Zhou , Linux-Fsdevel , Linux MM Subject: Re: [fsdax xfs] Regression panic at inode_switch_wbs_work_fn Message-ID: References: <20210717171713.GB22357@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=HArwuRLz; spf=none (imf20.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Rspamd-Server: rspam05 X-Stat-Signature: enbwxnrtybuewryzhj8kyc39opqoeznh X-Rspamd-Queue-Id: BBFDBD0000A2 X-HE-Tag: 1626564444-179771 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Jul 17, 2021 at 03:08:28PM -0700, Roman Gushchin wrote: > On Sat, Jul 17, 2021 at 10:17:13AM -0700, Darrick J. Wong wrote: > > On Fri, Jul 16, 2021 at 01:13:05PM -0700, Roman Gushchin wrote: > > > On Fri, Jul 16, 2021 at 01:57:55PM +0800, Murphy Zhou wrote: > > > > Hi, > > > > > > > > On Fri, Jul 16, 2021 at 12:07 AM Roman Gushchin wrote: > > > > > > > > > > On Thu, Jul 15, 2021 at 06:10:22PM +0800, Murphy Zhou wrote: > > > > > > Hi, > > > > > > > > > > > > #Looping generic/270 of xfstests[1] on pmem ramdisk with > > > > > > mount option: -o dax=always > > > > > > mkfs.xfs option: -f -b size=4096 -m reflink=0 > > > > > > can hit this panic now. > > > > > > > > > > > > #It's not reproducible on ext4. > > > > > > #It's not reproducible without dax=always. > > > > > > > > > > Hi Murphy! > > > > > > > > > > Thank you for the report! > > > > > > > > > > Can you, please, check if the following patch fixes the problem? > > > > > > > > No. Still the same panic. > > > > > > Hm, can you, please, double check this? It seems that the patch fixes the > > > problem for others (of course, it can be a different problem). > > > CCed you on the proper patch, just sent to the list. > > > > > > Otherwise, can you, please, say on which line of code the panic happens? > > > (using addr2line utility, for example) > > > > I experience the same problem that Murphy does, and I tracked it down > > to this chunk of inode_do_switch_wbs: > > > > /* > > * Count and transfer stats. Note that PAGECACHE_TAG_DIRTY points > > * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to > > * pages actually under writeback. > > */ > > xas_for_each_marked(&xas, page, ULONG_MAX, PAGECACHE_TAG_DIRTY) { > > here >>>>>>>>>> if (PageDirty(page)) { > > dec_wb_stat(old_wb, WB_RECLAIMABLE); > > inc_wb_stat(new_wb, WB_RECLAIMABLE); > > } > > } > > > > I suspect that "page" is really a pfn to a pmem mapping and not a real > > struct page. > > Good catch! Now it's clear that it's a different issue. > > I think as now the best option is to ignore dax inodes completely. > Can you, please, confirm, that the following patch solves the problem? > > Thanks! > > -- > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index 06d04a74ab6c..4c3370548982 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -521,6 +521,9 @@ static bool inode_prepare_wbs_switch(struct inode *inode, > */ > smp_mb(); > > + if (IS_DAX(inode)) > + return false; > + > /* while holding I_WB_SWITCH, no one else can update the association */ > spin_lock(&inode->i_lock); > if (!(inode->i_sb->s_flags & SB_ACTIVE) || That should work, but wouldn't it be better to test that at the top of inode_switch_wbs()? Or even earlier?