All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	Jan Kara <jack@suse.cz>,
	linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>
Subject: Re: yet another approach to fix loop autoclear for xfstets xfs/049
Date: Fri, 28 Jan 2022 08:08:03 +0100	[thread overview]
Message-ID: <20220128070803.GA2381@lst.de> (raw)
In-Reply-To: <7bebf860-2415-7eb6-55a1-47dc4439d9e9@I-love.SAKURA.ne.jp>

[nit: please properly trim the lines in your mails, this needed a
 reformat to be readable at all]

On Thu, Jan 27, 2022 at 10:05:45AM +0900, Tetsuo Handa wrote:
> I want to remove disk->open_mutex => lo->lo_mutex => I/O completion chain
> itself from /proc/lockdep . Even if real deadlock does not happen due to
> lo->lo_refcnt exclusion, I consider that disk->open_mutex => lo->lo_mutex
> dependency being recorded is a bad sign.
> It makes difficult to find real possibility of deadlock when things change
> in future. I consider that lo_release() is doing too much things under
> disk->open_mutex.
> 
> I tried to defer lo->lo_mutex in lo_release() as much as possible.
> But this chain still remains.

Yes.  To completely remove it we'd need something like:

 - remove lo_refcnt and rely on bd_openers on the whole device bdev
 - add a block layer flag to temporarily disable a gendisk and fail
   all opens for it.

For now I'd really like to just fix the regression, though.

  reply	other threads:[~2022-01-28  7:08 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-26 15:50 yet another approach to fix loop autoclear for xfstets xfs/049 Christoph Hellwig
2022-01-26 15:50 ` [PATCH 1/8] loop: de-duplicate the idle worker freeing code Christoph Hellwig
2022-01-27  9:36   ` Jan Kara
2022-01-26 15:50 ` [PATCH 2/8] loop: initialize the worker tracking fields once Christoph Hellwig
2022-01-27  9:45   ` Jan Kara
2022-01-26 15:50 ` [PATCH 3/8] block: remove the racy bd_inode->i_mapping->nrpages asserts Christoph Hellwig
2022-01-27  9:47   ` Jan Kara
2022-01-27  9:49     ` Christoph Hellwig
2022-01-27 12:23       ` Jan Kara
2022-01-28  7:26         ` Christoph Hellwig
2022-01-28 11:45           ` Jan Kara
2022-01-26 15:50 ` [PATCH 4/8] loop: only take lo_mutex for the last reference in lo_release Christoph Hellwig
2022-01-27  9:48   ` Jan Kara
2022-01-27 10:19     ` Jan Kara
2022-01-27 10:28       ` Christoph Hellwig
2022-01-26 15:50 ` [PATCH 5/8] loop: only take lo_mutex for the first reference in lo_open Christoph Hellwig
2022-01-27 10:28   ` Jan Kara
2022-01-27 10:31     ` Tetsuo Handa
2022-01-26 15:50 ` [PATCH 6/8] loop: don't freeze the queue in lo_release Christoph Hellwig
2022-01-27 10:42   ` Jan Kara
2022-01-28  6:46     ` Christoph Hellwig
2022-01-26 15:50 ` [PATCH 7/8] loop: only freeze the queue in __loop_clr_fd when needed Christoph Hellwig
2022-01-27 11:01   ` Jan Kara
2022-01-28  6:48     ` Christoph Hellwig
2022-01-26 15:50 ` [PATCH 8/8] loop: make autoclear operation synchronous again Christoph Hellwig
2022-01-27 11:04   ` Jan Kara
2022-01-26 19:38 ` yet another approach to fix loop autoclear for xfstets xfs/049 Darrick J. Wong
2022-01-27 16:50   ` Darrick J. Wong
2022-01-27  1:05 ` Tetsuo Handa
2022-01-28  7:08   ` Christoph Hellwig [this message]
2022-01-28  9:52     ` Tetsuo Handa

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=20220128070803.GA2381@lst.de \
    --to=hch@lst.de \
    --cc=axboe@kernel.dk \
    --cc=jack@suse.cz \
    --cc=linux-block@vger.kernel.org \
    --cc=ming.lei@redhat.com \
    --cc=penguin-kernel@I-love.SAKURA.ne.jp \
    /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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.