linux-kernel - Re: [PATCH v4 01/14] blk-mq: avoid sleep in blk_mq_alloc_request

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Message-Id: <167570056052.23119.7411390353642727169.b4-ty@kernel.dk>
Date:   Mon, 06 Feb 2023 09:22:40 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     hch@....de, dwagner@...e.de, hare@...e.de, ming.lei@...hat.com,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kemeng Shi <shikemeng@...weicloud.com>
Cc:     john.garry@...wei.com, jack@...e.cz
Subject: Re: [PATCH v4 01/14] blk-mq: avoid sleep in
 blk_mq_alloc_request_hctx


On Wed, 18 Jan 2023 17:37:13 +0800, Kemeng Shi wrote:
> Commit 1f5bd336b9150 ("blk-mq: add blk_mq_alloc_request_hctx") add
> blk_mq_alloc_request_hctx to send commands to a specific queue. If
> BLK_MQ_REQ_NOWAIT is not set in tag allocation, we may change to different
> hctx after sleep and get tag from unexpected hctx. So BLK_MQ_REQ_NOWAIT
> must be set in flags for blk_mq_alloc_request_hctx.
> After commit 600c3b0cea784 ("blk-mq: open code __blk_mq_alloc_request in
> blk_mq_alloc_request_hctx"), blk_mq_alloc_request_hctx return -EINVAL
> if both BLK_MQ_REQ_NOWAIT and BLK_MQ_REQ_RESERVED are not set instead of
> if BLK_MQ_REQ_NOWAIT is not set. So if BLK_MQ_REQ_NOWAIT is not set and
> BLK_MQ_REQ_RESERVED is set, blk_mq_alloc_request_hctx could alloc tag
> from unexpected hctx. I guess what we need here is that return -EINVAL
> if either BLK_MQ_REQ_NOWAIT or BLK_MQ_REQ_RESERVED is not set.
> 
> [...]

Applied, thanks!

[01/14] blk-mq: avoid sleep in blk_mq_alloc_request_hctx
        commit: 6ee858a3d3270a68902d66bb47c151a83622535c
[02/14] blk-mq: remove stale comment for blk_mq_sched_mark_restart_hctx
        commit: c31e76bcc379182fe67a82c618493b7b8868c672
[03/14] blk-mq: wait on correct sbitmap_queue in blk_mq_mark_tag_wait
        commit: 98b99e9412d0cde8c7b442bf5efb09528a2ede8b
[04/14] blk-mq: Fix potential io hung for shared sbitmap per tagset
        commit: 47df9ce95cd568d3f84218c4f65e9fbd4dfeda55
[05/14] blk-mq: remove unnecessary list_empty check in blk_mq_try_issue_list_directly
        commit: 08e3599e7401a7eae5e68f5e2601cc4a4e53951b
[06/14] blk-mq: remove unncessary from_schedule parameter in blk_mq_plug_issue_direct
        commit: 3e368fb023ffab83404f628d02789550d79eca9c
[07/14] blk-mq: make blk_mq_commit_rqs a general function for all commits
        commit: 34c9f547402f11c0241a44800574ec4fa38cccb8
[08/14] blk-mq: remove unncessary error count and commit in blk_mq_plug_issue_direct
        commit: 0d617a83e8d4d3149d76cc074d9779a3b0ee7baf
[09/14] blk-mq: use blk_mq_commit_rqs helper in blk_mq_try_issue_list_directly
        commit: 984ce0a7d75b577fd84f2cc7a83e6e2d2503f90e
[10/14] blk-mq: simplify flush check in blk_mq_dispatch_rq_list
        commit: e4ef2e05e0020db0d61b2cf451ef38a2bba33910
[11/14] blk-mq: remove unnecessary error count and check in blk_mq_dispatch_rq_list
        commit: 4ea58fe456c21bb259a7cbf8498946f86e9b84aa
[12/14] blk-mq: remove set of bd->last when get driver tag for next request fails
        commit: f1ce99f7098d9e7a322caf48eb8af05be7999827
[13/14] blk-mq: use switch/case to improve readability in blk_mq_try_issue_list_directly
        commit: 27e8b2bb149aff7b7b673b46c7206f4f37c30093
[14/14] blk-mq: correct stale comment of .get_budget
        commit: 01542f651a9f58a9b176c3d3dc3eefbacee53b78

Best regards,
-- 
Jens Axboe