This is a note to let you know that I've just added the patch titled
xfs: clear XFS_DQ_FREEING if we can't lock the dquot buffer to flush
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xfs-clear-xfs_dq_freeing-if-we-can-t-lock-the-dquot-buffer-to-flush.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Oct 31 08:07:17 AM CET 2022
From: Chandan Babu R <chandan.babu@xxxxxxxxxx>
Date: Mon, 31 Oct 2022 10:23:53 +0530
Subject: xfs: clear XFS_DQ_FREEING if we can't lock the dquot buffer to flush
To: gregkh@xxxxxxxxxxxxxxxxxxx
Cc: sashal@xxxxxxxxxx, mcgrof@xxxxxxxxxx, linux-xfs@xxxxxxxxxxxxxxx, stable@xxxxxxxxxxxxxxx, djwong@xxxxxxxxxx, chandan.babu@xxxxxxxxxx, amir73il@xxxxxxxxx, leah.rumancik@xxxxxxxxx
Message-ID: <20221031045354.183020-3-chandan.babu@xxxxxxxxxx>
From: Chandan Babu R <chandan.babu@xxxxxxxxxx>
From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
commit c97738a960a86081a147e7d436138e6481757445 upstream.
In commit 8d3d7e2b35ea, we changed xfs_qm_dqpurge to bail out if we
can't lock the dquot buf to flush the dquot. This prevents the AIL from
blocking on the dquot, but it also forgets to clear the FREEING flag on
its way out. A subsequent purge attempt will see the FREEING flag is
set and bail out, which leads to dqpurge_all failing to purge all the
dquots.
(copy-pasting from Dave Chinner's identical patch)
This was 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: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: Allison Collins <allison.henderson@xxxxxxxxxx>
Reviewed-by: Chandan Babu R <chandanrlinux@xxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
Acked-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Signed-off-by: Chandan Babu R <chandan.babu@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/xfs/xfs_qm.c | 1 +
1 file changed, 1 insertion(+)
--- 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);
Patches currently in stable-queue which might be from chandan.babu@xxxxxxxxxx are
queue-5.4/xfs-finish-dfops-on-every-insert-range-shift-iteration.patch
queue-5.4/xfs-force-the-log-after-remapping-a-synchronous-writes-file.patch
queue-5.4/xfs-clear-xfs_dq_freeing-if-we-can-t-lock-the-dquot-buffer-to-flush.patch
