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From: Ming Lei <ming.lei@redhat.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Damien Le Moal <dlemoal@kernel.org>
Subject: Re: [PATCH v3 4/6] block: Reduce the minimum value for the maximum DMA segment size
Date: Wed, 1 Apr 2026 09:12:38 +0800	[thread overview]
Message-ID: <acxxBsnoMhZo2iCk@fedora> (raw)
In-Reply-To: <70b6d783-fdd3-4dce-807a-80b0967906a3@acm.org>

On Tue, Mar 31, 2026 at 09:12:54AM -0700, Bart Van Assche wrote:
> On 3/30/26 5:57 PM, Ming Lei wrote:
> > What is the exactly code path you are trying to cover by changing
> > BLK_MIN_SEGMENT_SIZE?
> 
> In the solution I came up with and that we are no longer using in Android
> (we switched to the upstream approach) there were code paths
> that are only triggered if max_segment_size < PAGE_SIZE (see also
> https://lore.kernel.org/linux-block/20230522222554.525229-1-bvanassche@acm.org/).
> I'm not sure there are any such code paths left?

Then please setup one aarch64 VM with 16/64K PAGE_SIZE for covering the
code path.

It is insane to reduce BLK_MIN_SEGMENT_SIZE just for faking max_segment_size < PAGE_SIZE
in 4K page size kernel for test purpose only, IMO.


Thanks,
Ming


  reply	other threads:[~2026-04-01  1:12 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-27 21:13 [PATCH v3 0/6] Enable testing small DMA segment sizes Bart Van Assche
2026-03-27 21:13 ` [PATCH v3 1/6] block: Fix a source code comment Bart Van Assche
2026-03-27 21:13 ` [PATCH v3 2/6] block: Fix the max_user_sectors lower bound Bart Van Assche
2026-03-31 15:38   ` Christoph Hellwig
2026-03-27 21:13 ` [PATCH v3 3/6] block: Fix the DMA segment boundary mask check Bart Van Assche
2026-03-31 15:39   ` Christoph Hellwig
2026-03-27 21:13 ` [PATCH v3 4/6] block: Reduce the minimum value for the maximum DMA segment size Bart Van Assche
2026-03-29 14:38   ` Ming Lei
2026-03-30 19:49     ` Bart Van Assche
2026-03-31  0:57       ` Ming Lei
2026-03-31 16:12         ` Bart Van Assche
2026-04-01  1:12           ` Ming Lei [this message]
2026-03-27 21:13 ` [PATCH v3 5/6] null_blk: Support configuring " Bart Van Assche
2026-03-29 12:30   ` Nilay Shroff
2026-03-30  2:23     ` Ming Lei
2026-03-30  6:13       ` Nilay Shroff
2026-03-27 21:13 ` [PATCH v3 6/6] scsi_debug: Support configuring the maximum " Bart Van Assche
2026-03-31  8:44   ` John Garry

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