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From: Christoph Hellwig <hch@lst.de>
To: Josef Bacik <josef@toxicpanda.com>
Cc: Christoph Hellwig <hch@lst.de>, Chris Mason <clm@fb.com>,
	David Sterba <dsterba@suse.com>,
	linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: small writeback fixes
Date: Wed, 19 Jul 2023 07:39:01 +0200	[thread overview]
Message-ID: <20230719053901.GA3241@lst.de> (raw)
In-Reply-To: <20230718171744.GA843162@perftesting>

On Tue, Jul 18, 2023 at 01:17:44PM -0400, Josef Bacik wrote:
> Just FYI I've been using these two series to see how the github CI stuff was
> working, and I keep tripping over a hang in generic/475.  It appears to be in
> the fixup worker, here's the sysrq w output

> 
> We appear to be getting hung up because the ENOSPC stuff is flushing and waiting
> on ordered extents, and then the fixup worker is waiting on trying to reserve
> space.  My hunch is the page that's in the fixup worker is attached to an
> ordered extent.
> 
> I can pretty reliably reproduce this in the CI, so if you have trouble
> reproducing it let me know.  I'll dig into it later today, but I may not get to
> it before you do.  Thanks,

My day was already over by the time you sent this, but I looked into
it the first thing this morning.

I can't reproduce the hang, but my first thought was "why the heck do
even end up in the fixup worker" given that there is no GUP-based
dirtying in the thread.

I can reproduce the test case hitting the fixup worker now, while
I can't on misc-next.  Looking into it now, but the rework of the
fixup logic is a hot candidate.

  reply	other threads:[~2023-07-19  5:39 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-13 13:04 small writeback fixes Christoph Hellwig
2023-07-13 13:04 ` [PATCH 1/9] btrfs: don't stop integrity writeback too early Christoph Hellwig
2023-07-13 13:04 ` [PATCH 2/9] btrfs: don't wait for writeback on clean pages in extent_write_cache_pages Christoph Hellwig
2023-07-13 13:04 ` [PATCH 3/9] btrfs: fix an error handling corner case in cow_file_range Christoph Hellwig
2023-07-13 13:04 ` [PATCH 4/9] btrfs: move the cow_fixup earlier in writepages handling Christoph Hellwig
2023-07-13 13:04 ` [PATCH 5/9] btrfs: fix handling of errors from __extent_writepage_io Christoph Hellwig
2023-07-13 13:04 ` [PATCH 6/9] btrfs: stop submitting I/O after an error in extent_write_locked_range Christoph Hellwig
2023-07-13 13:04 ` [PATCH 7/9] btrfs: fix a race in clearing the writeback bit for sub-page I/O Christoph Hellwig
2023-07-13 13:04 ` [PATCH 8/9] btrfs: remove the call to btrfs_mark_ordered_io_finished in btrfs_writepage_fixup_worker Christoph Hellwig
2023-07-13 13:04 ` [PATCH 9/9] btrfs: lift the call to mapping_set_error out of cow_file_range Christoph Hellwig
2023-07-14 13:59 ` small writeback fixes Josef Bacik
2023-07-18 17:17 ` Josef Bacik
2023-07-19  5:39   ` Christoph Hellwig [this message]
2023-07-19 11:50     ` Christoph Hellwig
2023-07-19 14:30       ` Josef Bacik
2023-07-19 15:25         ` Christoph Hellwig
2023-07-19 21:42       ` Josef Bacik
2023-07-20  4:48         ` Christoph Hellwig

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