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Date: Tue, 16 Jun 2026 10:05:29 -0600
From: Keith Busch <kbusch@kernel.org>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Vjaceslavs Klimovs <vklimovs@gmail.com>,
	"Dr. David Alan Gilbert" <linux@treblig.org>,
	Thorsten Leemhuis <regressions@leemhuis.info>, trnka@scm.com,
	Zdenek Kabelac <zdenek.kabelac@gmail.com>,
	linux-block@vger.kernel.org, dm-devel@lists.linux.dev,
	Linux kernel regressions list <regressions@lists.linux.dev>
Subject: Re: Repeatable, raid1+O_DIRECT, hang/warn
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On Tue, Jun 16, 2026 at 05:55:13PM +0200, Mikulas Patocka wrote:
> I thought that reverting 5ff3f74e145a and re-introducing the alignment 
> check in block/fops.c:blkdev_dio_invalid would fix it - but it wouldn't.
> 
> The same problem existed even before 5ff3f74e145a, with the pvmove 
> command.

Also before 5ff3f74e145a, you could still have devices that are
perfectly fine with dword aligned dma, so sub-sector vectors  would have
passed the checks and gone through to dm-raid, which would have
miscounted the remaining.
 
> So, I think that the proper way to fix this is to teach dm-mirror/dm-io to 
> deal with unaligned bio vectors and handle them properly.

The block layer already handles it, so I think just dispatch it and
check the bi_status is all the stacking drivers need to do.