From: Mike Snitzer <snitzer@redhat.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
Kent Overstreet <kent.overstreet@gmail.com>
Subject: Re: [PATCH 0/3] block: fix mismatch of figuring out physical segment number
Date: Tue, 31 Jul 2018 11:32:18 -0400 [thread overview]
Message-ID: <20180731153218.GA17281@redhat.com> (raw)
In-Reply-To: <20180731104914.17249-1-ming.lei@redhat.com>
On Tue, Jul 31 2018 at 6:49am -0400,
Ming Lei <ming.lei@redhat.com> wrote:
> Hi,
>
> This patchset fixes one issue related with physical segment computation,
> which is found by Mike. In case of dm-rq, the warning of 'blk_cloned_rq_check_limits:
> over max segments limit' can be triggered easily.
>
> Follows the cause:
>
> 1) in IO fast path(blk_queue_split()), we always figure out physical segment number
> no matter the flag of QUEUE_FLAG_NO_SG_MERGE is set or not.
>
> 2) only blk_recount_segments() and blk_recalc_rq_segments() uses the flag of
> QUEUE_FLAG_NO_SG_MERGE, but the two are only called in some unusual
> cases, such as request clone in dm-rq.
>
> 3) the above two computation don't match, and cause the warning of
> "blk_cloned_rq_check_limits: over max segments limit".
>
> This patchset fixes this issue by killing the queue flag since it is basically
> bypassed since v4.4, and no one complains that at all. Also multipage bvec will
> come soon, and it doesn't make sense to keep QUEUE_FLAG_NO_SG_MERGE any more.
Thanks Ming, for the series:
Acked-by: Mike Snitzer <snitzer@redhat.com>
next prev parent reply other threads:[~2018-07-31 15:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-31 10:49 [PATCH 0/3] block: fix mismatch of figuring out physical segment number Ming Lei
2018-07-31 10:49 ` [PATCH 1/3] block: don't use bio->bi_vcnt to figure out " Ming Lei
2018-08-01 14:52 ` Christoph Hellwig
2018-07-31 10:49 ` [PATCH 2/3] block: kill QUEUE_FLAG_NO_SG_MERGE Ming Lei
2018-08-01 14:54 ` Christoph Hellwig
2018-08-01 23:11 ` Ming Lei
2018-07-31 10:49 ` [PATCH 3/3] block: kill BLK_MQ_F_SG_MERGE Ming Lei
2018-07-31 15:32 ` Mike Snitzer [this message]
2018-08-06 2:37 ` [PATCH 0/3] block: fix mismatch of figuring out physical segment number Ming Lei
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