From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
brauner@kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] iomap: add a separate bio_set for iomap_split_ioend
Date: Tue, 30 Jun 2026 07:17:04 +0200 [thread overview]
Message-ID: <20260630051704.GD20771@lst.de> (raw)
In-Reply-To: <20260629225831.GG6095@frogsfrogsfrogs>
On Mon, Jun 29, 2026 at 03:58:31PM -0700, Darrick J. Wong wrote:
> On Mon, Jun 29, 2026 at 02:52:29PM +0200, Christoph Hellwig wrote:
> > iomap_split_ioend can split bios that already come from
> > iomap_ioend_bioset and thus deadlock when the bioset is exhausted.
> >
> > Add a separate bio_set to avoid this deadlock.
>
> What happens if &iomap_ioend_split_bioset is exhausted?
mempool_alloc will block waiting for an ioend to finish.
> Won't that also stall the ioend submission?
Yes, but at least it won't deadlock, unlike the case where we're
waiting for the parent one to finish. (multiply a few times
as there is more than one entry in the mempool, which is what's
saving our ass in practice)
next prev parent reply other threads:[~2026-06-30 5:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-29 12:52 [PATCH] iomap: add a separate bio_set for iomap_split_ioend Christoph Hellwig
2026-06-29 22:58 ` Darrick J. Wong
2026-06-30 5:17 ` Christoph Hellwig [this message]
2026-06-30 10:59 ` Christian Brauner
2026-07-07 5:04 ` Christoph Hellwig
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