public inbox for linux-block@vger.kernel.org
 help / color / mirror / Atom feed
From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>, Damien Le Moal <dlemoal@kernel.org>,
	Nilay Shroff <nilay@linux.ibm.com>,
	linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
	nbd@other.debian.org, linux-scsi@vger.kernel.org,
	usb-storage@lists.one-eyed-alien.net,
	Johannes Thumshirn <johannes.thumshirn@wdc.com>
Subject: Re: [PATCH 04/11] block: don't update BLK_FEAT_POLL in __blk_mq_update_nr_hw_queues
Date: Thu, 9 Jan 2025 16:16:14 +0800	[thread overview]
Message-ID: <Z3-Fzrj-En-l82Uc@fedora> (raw)
In-Reply-To: <20250109055810.1402918-5-hch@lst.de>

On Thu, Jan 09, 2025 at 06:57:25AM +0100, Christoph Hellwig wrote:
> When __blk_mq_update_nr_hw_queues changes the number of tag sets, it
> might have to disable poll queues.  Currently it does so by adjusting
> the BLK_FEAT_POLL, which is a bit against the intent of features that
> describe hardware / driver capabilities, but more importantly causes
> nasty lock order problems with the broadly held freeze when updating the
> number of hardware queues and the limits lock.  Fix this by leaving
> BLK_FEAT_POLL alone, and instead check for the number of poll queues in
> the bio submission and poll handlers.  While this adds extra work to the
> fast path, the variables are in cache lines used by these operations
> anyway, so it should be cheap enough.
> 
> Fixes: 8023e144f9d6 ("block: move the poll flag to queue_limits")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Reviewed-by: Ming Lei <ming.lei@redhat.com>

Thanks,
Ming


  reply	other threads:[~2025-01-09  8:16 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-01-09  5:57 fix queue freeze and limit locking order v3 Christoph Hellwig
2025-01-09  5:57 ` [PATCH 01/11] block: fix docs for freezing of queue limits updates Christoph Hellwig
2025-01-09  5:57 ` [PATCH 02/11] block: add a queue_limits_commit_update_frozen helper Christoph Hellwig
2025-01-09 11:33   ` John Garry
2025-01-09  5:57 ` [PATCH 03/11] block: check BLK_FEAT_POLL under q_usage_count Christoph Hellwig
2025-01-09  8:14   ` Ming Lei
2025-01-09  9:03   ` Nilay Shroff
2025-01-09  5:57 ` [PATCH 04/11] block: don't update BLK_FEAT_POLL in __blk_mq_update_nr_hw_queues Christoph Hellwig
2025-01-09  8:16   ` Ming Lei [this message]
2025-01-09  9:01   ` Nilay Shroff
2025-01-09  5:57 ` [PATCH 05/11] block: add a store_limit operations for sysfs entries Christoph Hellwig
2025-01-09  5:57 ` [PATCH 06/11] block: fix queue freeze vs limits lock order in sysfs store methods Christoph Hellwig
2025-01-09 13:07   ` John Garry
2025-01-10  9:33     ` Christoph Hellwig
2025-01-09  5:57 ` [PATCH 07/11] nvme: fix queue freeze vs limits lock order Christoph Hellwig
2025-01-09  5:57 ` [PATCH 08/11] nbd: " Christoph Hellwig
2025-01-09  5:57 ` [PATCH 09/11] usb-storage: " Christoph Hellwig
2025-01-09  5:57 ` [PATCH 10/11] loop: refactor queue limits updates Christoph Hellwig
2025-01-09  9:11   ` Nilay Shroff
2025-01-09  5:57 ` [PATCH 11/11] loop: fix queue freeze vs limits lock order Christoph Hellwig
2025-01-09 14:57 ` fix queue freeze and limit locking order v3 Martin K. Petersen
  -- strict thread matches above, loose matches on Subject: below --
2025-01-10  5:47 fix queue freeze and limit locking order v4 Christoph Hellwig
2025-01-10  5:47 ` [PATCH 04/11] block: don't update BLK_FEAT_POLL in __blk_mq_update_nr_hw_queues Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=Z3-Fzrj-En-l82Uc@fedora \
    --to=ming.lei@redhat.com \
    --cc=axboe@kernel.dk \
    --cc=dlemoal@kernel.org \
    --cc=hch@lst.de \
    --cc=johannes.thumshirn@wdc.com \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-nvme@lists.infradead.org \
    --cc=linux-scsi@vger.kernel.org \
    --cc=nbd@other.debian.org \
    --cc=nilay@linux.ibm.com \
    --cc=usb-storage@lists.one-eyed-alien.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox