From: Christoph Hellwig <hch@lst.de>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Damien Le Moal <dlemoal@kernel.org>,
Mike Snitzer <snitzer@kernel.org>,
Mikulas Patocka <mpatocka@redhat.com>,
linux-block@vger.kernel.org, dm-devel@lists.linux.dev
Subject: Re: add a flag to allow underordered zoned writes
Date: Wed, 19 Nov 2025 08:58:00 +0100 [thread overview]
Message-ID: <20251119075800.GA23083@lst.de> (raw)
In-Reply-To: <f385de59-5bef-4ddf-b363-edf76f88d855@acm.org>
On Tue, Nov 18, 2025 at 10:10:33PM -0800, Bart Van Assche wrote:
> Is the following deadlock inherent to this approach?
> - Several bios are present on zwplug->bio_list and these bios cannot be
> submitted because their starting offset is past the write pointer.
> - No new bios can be allocated because all memory is in use.
> - A deadlock occurs because none of the queued bios can be submitted
> and no new bio can be allocated.
This can if the number of in-flight bios is larger than bio mempool
reserve. Which is real, but we also have this in various other
submitters that hold bios to submit in a list. This suggests it is
mostly theoretical, but I'd still love to address it for all these
cases.
next prev parent reply other threads:[~2025-11-19 7:58 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-18 7:03 add a flag to allow underordered zoned writes Christoph Hellwig
2025-11-18 7:03 ` [PATCH 1/3] block: add a bio_list_add_sorted helper Christoph Hellwig
2025-11-19 3:09 ` Damien Le Moal
2025-11-18 7:03 ` [PATCH 2/3] block: add a REQ_ZWPLUG_UNORDERED flag Christoph Hellwig
2025-11-19 3:17 ` Damien Le Moal
2025-11-18 7:03 ` [PATCH 3/3] dm-kcopyd: use REQ_ZWPLUG_UNORDERED Christoph Hellwig
2025-11-19 3:18 ` Damien Le Moal
2025-11-19 6:10 ` add a flag to allow underordered zoned writes Bart Van Assche
2025-11-19 7:58 ` Christoph Hellwig [this message]
2025-11-19 17:00 ` Jens Axboe
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