From: Christoph Hellwig <hch@lst.de>
To: Hans Holmberg <hans.holmberg@wdc.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Keith Busch <kbusch@kernel.org>,
Damien Le Moal <dlemoal@kernel.org>,
Johannes Thumshirn <johannes.thumshirn@wdc.com>,
Christoph Hellwig <hch@lst.de>,
Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>,
Andreas Hindborg <a.hindborg@kernel.org>
Subject: Re: [PATCH] null_blk: set dma alignment to logical block size
Date: Wed, 29 Oct 2025 14:51:17 +0100 [thread overview]
Message-ID: <20251029135117.GB15688@lst.de> (raw)
In-Reply-To: <20251029135103.GA15688@lst.de>
On Wed, Oct 29, 2025 at 02:51:03PM +0100, Christoph Hellwig wrote:
> On Wed, Oct 29, 2025 at 02:39:56PM +0100, Hans Holmberg wrote:
> > This driver assumes that bio vectors are memory aligned to the logical
> > block size, so set the queue limit to reflect that.
> >
> > Unless we set up the limit based on the logical block size, we will go
> > out of page bounds in copy_to_nullb / copy_from_nullb.
> >
> > Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
> > ---
> >
> > A fixes tag would be in order, but I have not figured out exactly when
> > this became a problem.
>
> In theory probably since day 1, and in practice since direct I/O allowed
> less than lba size memory alignment:
>
> Fixes: bf8d08532bc1 ("iomap: add support for dma aligned direct-io")
> Fixes: b1a000d3b8ec ("block: relax direct io memory alignment")
Oh, and the patch itself of course looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
next prev parent reply other threads:[~2025-10-29 13:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-29 13:39 [PATCH] null_blk: set dma alignment to logical block size Hans Holmberg
2025-10-29 13:51 ` Christoph Hellwig
2025-10-29 13:51 ` Christoph Hellwig [this message]
2025-10-29 14:12 ` Keith Busch
2025-10-29 15:32 ` Hans Holmberg
2025-10-29 16:01 ` Hans Holmberg
2025-10-29 16:06 ` Keith Busch
2025-10-29 16:15 ` Keith Busch
2025-10-30 12:32 ` Hans Holmberg
2025-10-31 9:00 ` Christoph Hellwig
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