From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Damien Le Moal <damien.lemoal@wdc.com>,
Andreas Dilger <adilger.kernel@dilger.ca>,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
Johannes Thumshirn <jthumshirn@suse.de>,
Naohiro Aota <naohiro.aota@wdc.com>,
Masato Suzuki <masato.suzuki@wdc.com>
Subject: Re: [PATCH] ext4: Fix deadlock on page reclaim
Date: Fri, 26 Jul 2019 18:55:08 -0400 [thread overview]
Message-ID: <20190726225508.GA13729@mit.edu> (raw)
In-Reply-To: <20190726224423.GE7777@dread.disaster.area>
On Sat, Jul 27, 2019 at 08:44:23AM +1000, Dave Chinner wrote:
> >
> > This looks like something that could hit every file systems, so
> > shouldn't we fix this in common code? We could also look into
> > just using memalloc_nofs_save for the page cache allocation path
> > instead of the per-mapping gfp_mask.
>
> I think it has to be the entire IO path - any allocation from the
> underlying filesystem could recurse into the top level filesystem
> and then deadlock if the memory reclaim submits IO or blocks on
> IO completion from the upper filesystem. That's a bloody big hammer
> for something that is only necessary when there are stacked
> filesystems like this....
Yeah.... that's why using memalloc_nofs_save() probably makes the most
sense, and dm_zoned should use that before it calls into ext4.
- Ted
next prev parent reply other threads:[~2019-07-26 22:55 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 9:33 [PATCH] ext4: Fix deadlock on page reclaim Damien Le Moal
2019-07-25 11:54 ` Christoph Hellwig
2019-07-25 19:57 ` Andreas Dilger
2019-07-26 2:24 ` Damien Le Moal
2019-07-26 22:44 ` Dave Chinner
2019-07-26 22:55 ` Theodore Y. Ts'o [this message]
2019-07-27 2:59 ` Damien Le Moal
2019-07-28 23:41 ` Dave Chinner
2019-07-29 1:07 ` Damien Le Moal
2019-07-29 18:40 ` Andreas Dilger
2019-07-30 2:06 ` Damien Le Moal
2019-07-30 23:47 ` Dave Chinner
2019-07-31 4:37 ` Damien Le Moal
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