From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Christian Brauner <brauner@kernel.org>,
Carlos Maiolino <cem@kernel.org>, Qu Wenruo <wqu@suse.com>,
Al Viro <viro@zeniv.linux.org.uk>,
linux-block@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 02/14] block: open code bio_add_page and fix handling of mismatching P2P ranges
Date: Fri, 23 Jan 2026 06:43:14 +0100 [thread overview]
Message-ID: <20260123054314.GA24902@lst.de> (raw)
In-Reply-To: <20260122175908.GZ5945@frogsfrogsfrogs>
On Thu, Jan 22, 2026 at 09:59:08AM -0800, Darrick J. Wong wrote:
> On Mon, Jan 19, 2026 at 08:44:09AM +0100, Christoph Hellwig wrote:
> > bio_add_page fails to add data to the bio when mixing P2P with non-P2P
> > ranges, or ranges that map to different P2P providers. In that case
> > it will trigger that WARN_ON and return an error up the chain instead of
> > simply starting a new bio as intended. Fix this by open coding
>
> AFAICT we've already done all the other checks in bio_add_page, so
> calling __bio_add_page directly from within the loop is ok since you've
> explicitly handled the !zone_device_pages_have_same_pgmap() case.
>
> > bio_add_page and handling this case explicitly. While doing so, stop
> > merging physical contiguous data that belongs to multiple folios. While
> > this merge could lead to more efficient bio packing in some case,
> > dropping will allow to remove handling of this corner case in other
> > places and make the code more robust.
>
> That does sound like a landmine waiting to go off...
What? Removing the handling?
next prev parent reply other threads:[~2026-01-23 5:43 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20260123121444epcas5p4e729259011e031a28be8379ea3b9b749@epcas5p4.samsung.com>
2026-01-19 7:44 ` bounce buffer direct I/O when stable pages are required v2 Christoph Hellwig
2026-01-19 7:44 ` [PATCH 01/14] block: refactor get_contig_folio_len Christoph Hellwig
2026-01-22 11:00 ` Johannes Thumshirn
2026-01-22 17:54 ` Darrick J. Wong
2026-01-23 8:32 ` Damien Le Moal
2026-01-23 8:35 ` Christoph Hellwig
2026-01-23 8:44 ` Damien Le Moal
2026-01-23 8:45 ` Damien Le Moal
2026-01-23 12:14 ` Anuj Gupta
2026-01-19 7:44 ` [PATCH 02/14] block: open code bio_add_page and fix handling of mismatching P2P ranges Christoph Hellwig
2026-01-22 11:04 ` Johannes Thumshirn
2026-01-22 17:59 ` Darrick J. Wong
2026-01-23 5:43 ` Christoph Hellwig [this message]
2026-01-23 7:05 ` Darrick J. Wong
2026-01-23 8:35 ` Damien Le Moal
2026-01-23 12:15 ` Anuj Gupta
2026-01-19 7:44 ` [PATCH 03/14] iov_iter: extract a iov_iter_extract_bvecs helper from bio code Christoph Hellwig
2026-01-22 17:47 ` Darrick J. Wong
2026-01-23 5:44 ` Christoph Hellwig
2026-01-23 7:09 ` Darrick J. Wong
2026-01-23 7:14 ` Christoph Hellwig
2026-01-23 11:37 ` David Howells
2026-01-23 13:58 ` Christoph Hellwig
2026-01-23 14:57 ` David Howells
2026-01-26 17:36 ` Matthew Wilcox
2026-01-27 5:13 ` Christoph Hellwig
2026-01-27 5:44 ` Matthew Wilcox
2026-01-27 5:47 ` Christoph Hellwig
2026-02-03 8:20 ` Askar Safin
2026-02-03 10:28 ` Askar Safin
2026-02-03 16:32 ` Christoph Hellwig
2026-01-19 7:44 ` [PATCH 04/14] block: remove bio_release_page Christoph Hellwig
2026-01-22 11:14 ` Johannes Thumshirn
2026-01-22 17:26 ` Darrick J. Wong
2026-01-23 8:43 ` Damien Le Moal
2026-01-23 12:17 ` Anuj Gupta
2026-01-19 7:44 ` [PATCH 05/14] block: add helpers to bounce buffer an iov_iter into bios Christoph Hellwig
2026-01-22 13:05 ` Johannes Thumshirn
2026-01-22 17:25 ` Darrick J. Wong
2026-01-23 5:51 ` Christoph Hellwig
2026-01-23 7:11 ` Darrick J. Wong
2026-01-23 7:16 ` Christoph Hellwig
2026-01-23 8:52 ` Damien Le Moal
2026-01-23 12:20 ` Anuj Gupta
2026-01-19 7:44 ` [PATCH 06/14] iomap: fix submission side handling of completion side errors Christoph Hellwig
2026-01-19 17:40 ` Darrick J. Wong
2026-01-23 8:54 ` Damien Le Moal
2026-01-19 7:44 ` [PATCH 07/14] iomap: simplify iomap_dio_bio_iter Christoph Hellwig
2026-01-19 17:43 ` Darrick J. Wong
2026-01-23 8:55 ` Damien Le Moal
2026-01-19 7:44 ` [PATCH 08/14] iomap: split out the per-bio logic from iomap_dio_bio_iter Christoph Hellwig
2026-01-23 8:57 ` Damien Le Moal
2026-01-19 7:44 ` [PATCH 09/14] iomap: share code between iomap_dio_bio_end_io and iomap_finish_ioend_direct Christoph Hellwig
2026-01-23 8:58 ` Damien Le Moal
2026-01-19 7:44 ` [PATCH 10/14] iomap: free the bio before completing the dio Christoph Hellwig
2026-01-19 17:43 ` Darrick J. Wong
2026-01-23 8:59 ` Damien Le Moal
2026-01-19 7:44 ` [PATCH 11/14] iomap: rename IOMAP_DIO_DIRTY to IOMAP_DIO_USER_BACKED Christoph Hellwig
2026-01-23 9:00 ` Damien Le Moal
2026-01-19 7:44 ` [PATCH 12/14] iomap: support ioends for direct reads Christoph Hellwig
2026-01-23 9:02 ` Damien Le Moal
2026-01-19 7:44 ` [PATCH 13/14] iomap: add a flag to bounce buffer direct I/O Christoph Hellwig
2026-01-23 9:05 ` Damien Le Moal
2026-01-19 7:44 ` [PATCH 14/14] xfs: use bounce buffering direct I/O when the device requires stable pages Christoph Hellwig
2026-01-19 17:45 ` Darrick J. Wong
2026-01-23 9:08 ` Damien Le Moal
2026-01-23 12:10 ` bounce buffer direct I/O when stable pages are required v2 Anuj Gupta
2026-01-23 14:01 ` Christoph Hellwig
2026-01-23 14:09 ` Keith Busch
2026-01-23 12:24 ` Christian Brauner
2026-01-23 14:10 ` block or iomap tree, was: " Christoph Hellwig
2026-01-27 10:31 ` Christian Brauner
2026-01-27 12:50 ` Christoph Hellwig
2026-01-14 7:40 bounce buffer direct I/O when stable pages are required Christoph Hellwig
2026-01-14 7:41 ` [PATCH 02/14] block: open code bio_add_page and fix handling of mismatching P2P ranges Christoph Hellwig
2026-01-14 12:46 ` Johannes Thumshirn
2026-01-14 13:01 ` hch
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