From patchwork Wed Jul 1 07:51:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Chinner X-Patchwork-Id: 11635581 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2D808913 for ; Wed, 1 Jul 2020 07:51:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1EA9E2074D for ; Wed, 1 Jul 2020 07:51:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728379AbgGAHvt (ORCPT ); Wed, 1 Jul 2020 03:51:49 -0400 Received: from mail109.syd.optusnet.com.au ([211.29.132.80]:60493 "EHLO mail109.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728294AbgGAHvt (ORCPT ); Wed, 1 Jul 2020 03:51:49 -0400 Received: from dread.disaster.area (pa49-180-53-24.pa.nsw.optusnet.com.au [49.180.53.24]) by mail109.syd.optusnet.com.au (Postfix) with ESMTPS id 7D8C9D7B589 for ; Wed, 1 Jul 2020 17:51:45 +1000 (AEST) Received: from discord.disaster.area ([192.168.253.110]) by dread.disaster.area with esmtp (Exim 4.92.3) (envelope-from ) id 1jqXWy-0003uZ-KS for linux-xfs@vger.kernel.org; Wed, 01 Jul 2020 17:51:44 +1000 Received: from dave by discord.disaster.area with local (Exim 4.93) (envelope-from ) id 1jqXWy-00B3ED-Br for linux-xfs@vger.kernel.org; Wed, 01 Jul 2020 17:51:44 +1000 From: Dave Chinner To: linux-xfs@vger.kernel.org Subject: [PATCH] xfs: fix quota off hang from non-blocking flush Date: Wed, 1 Jul 2020 17:51:44 +1000 Message-Id: <20200701075144.2633976-1-david@fromorbit.com> X-Mailer: git-send-email 2.26.2.761.g0e0b3e54be MIME-Version: 1.0 X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=QIgWuTDL c=1 sm=1 tr=0 a=moVtWZxmCkf3aAMJKIb/8g==:117 a=moVtWZxmCkf3aAMJKIb/8g==:17 a=_RQrkK6FrEwA:10 a=20KFwNOVAAAA:8 a=3FCIVe6-SOTBwgIUsdsA:9 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: Dave Chinner Found by inspection after having xfs/305 hang 1 in ~50 iterations in a quotaoff operation: [ 8872.301115] xfs_quota D13888 92262 91813 0x00004002 [ 8872.302538] Call Trace: [ 8872.303193] __schedule+0x2d2/0x780 [ 8872.304108] ? do_raw_spin_unlock+0x57/0xd0 [ 8872.305198] schedule+0x6e/0xe0 [ 8872.306021] schedule_timeout+0x14d/0x300 [ 8872.307060] ? __next_timer_interrupt+0xe0/0xe0 [ 8872.308231] ? xfs_qm_dqusage_adjust+0x200/0x200 [ 8872.309422] schedule_timeout_uninterruptible+0x2a/0x30 [ 8872.310759] xfs_qm_dquot_walk.isra.0+0x15a/0x1b0 [ 8872.311971] xfs_qm_dqpurge_all+0x7f/0x90 [ 8872.313022] xfs_qm_scall_quotaoff+0x18d/0x2b0 [ 8872.314163] xfs_quota_disable+0x3a/0x60 [ 8872.315179] kernel_quotactl+0x7e2/0x8d0 [ 8872.316196] ? __do_sys_newstat+0x51/0x80 [ 8872.317238] __x64_sys_quotactl+0x1e/0x30 [ 8872.318266] do_syscall_64+0x46/0x90 [ 8872.319193] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 8872.320490] RIP: 0033:0x7f46b5490f2a [ 8872.321414] Code: Bad RIP value. Returning -EAGAIN from xfs_qm_dqpurge() without clearing the XFS_DQ_FREEING flag means the xfs_qm_dqpurge_all() code can never free the dquot, and we loop forever waiting for the XFS_DQ_FREEING flag to go away on the dquot that leaked it via -EAGAIN. Fixes: 8d3d7e2b35ea ("xfs: trylock underlying buffer on dquot flush") Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Brian Foster --- fs/xfs/xfs_qm.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c index d6cd83317344..938023dd8ce5 100644 --- a/fs/xfs/xfs_qm.c +++ b/fs/xfs/xfs_qm.c @@ -148,6 +148,7 @@ xfs_qm_dqpurge( error = xfs_bwrite(bp); xfs_buf_relse(bp); } else if (error == -EAGAIN) { + dqp->dq_flags &= ~XFS_DQ_FREEING; goto out_unlock; } xfs_dqflock(dqp);