Linux-XFS Archive on lore.kernel.org
 help / color / Atom feed
From: Brian Foster <bfoster@redhat.com>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH] xfs: fix quota off hang from non-blocking flush
Date: Wed, 1 Jul 2020 06:50:23 -0400
Message-ID: <20200701105023.GA64483@bfoster> (raw)
In-Reply-To: <20200701075144.2633976-1-david@fromorbit.com>

On Wed, Jul 01, 2020 at 05:51:44PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> 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 <dchinner@redhat.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  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);
> -- 
> 2.26.2.761.g0e0b3e54be
> 


      parent reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-01  7:51 Dave Chinner
2020-07-01  8:05 ` Christoph Hellwig
2020-07-01 10:50 ` Brian Foster [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200701105023.GA64483@bfoster \
    --to=bfoster@redhat.com \
    --cc=david@fromorbit.com \
    --cc=linux-xfs@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-XFS Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-xfs/0 linux-xfs/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-xfs linux-xfs/ https://lore.kernel.org/linux-xfs \
		linux-xfs@vger.kernel.org
	public-inbox-index linux-xfs

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-xfs


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git