From: Nilay Shroff <nilay@linux.ibm.com>
To: Bart Van Assche <bvanassche@acm.org>, Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
Ming Lei <ming.lei@redhat.com>, Martin Wilck <mwilck@suse.com>,
Benjamin Marzinski <bmarzins@redhat.com>,
stable@vger.kernel.org, Hannes Reinecke <hare@suse.de>,
Damien Le Moal <dlemoal@kernel.org>,
Chaitanya Kulkarni <kch@nvidia.com>
Subject: Re: [PATCH v6 2/2] block: Remove queue freezing from several sysfs store callbacks
Date: Tue, 18 Nov 2025 12:26:10 +0530 [thread overview]
Message-ID: <d35a4c76-cb9c-4fda-9d5c-c9ff8514c4c5@linux.ibm.com> (raw)
In-Reply-To: <20251114210409.3123309-3-bvanassche@acm.org>
On 11/15/25 2:34 AM, Bart Van Assche wrote:
> Freezing the request queue from inside sysfs store callbacks may cause a
> deadlock in combination with the dm-multipath driver and the
> queue_if_no_path option. Additionally, freezing the request queue slows
> down system boot on systems where sysfs attributes are set synchronously.
>
> Fix this by removing the blk_mq_freeze_queue() / blk_mq_unfreeze_queue()
> calls from the store callbacks that do not strictly need these callbacks.
> Add the __data_racy annotation to request_queue.rq_timeout to suppress
> KCSAN data race reports about the rq_timeout reads.
>
> This patch may cause a small delay in applying the new settings.
>
> For all the attributes affected by this patch, I/O will complete
> correctly whether the old or the new value of the attribute is used.
>
> This patch affects the following sysfs attributes:
> * io_poll_delay
> * io_timeout
> * nomerges
> * read_ahead_kb
> * rq_affinity
Looks good to me:
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
next prev parent reply other threads:[~2025-11-18 6:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-14 21:04 [PATCH v6 0/2] Fix a recently introduced deadlock Bart Van Assche
2025-11-14 21:04 ` [PATCH v6 1/2] fs: Add the __data_racy annotation to backing_dev_info.ra_pages Bart Van Assche
2025-11-18 6:55 ` Nilay Shroff
2025-11-14 21:04 ` [PATCH v6 2/2] block: Remove queue freezing from several sysfs store callbacks Bart Van Assche
2025-11-17 9:01 ` Nilay Shroff
2025-11-17 20:44 ` Bart Van Assche
2025-11-18 6:54 ` Nilay Shroff
2025-11-18 6:56 ` Nilay Shroff [this message]
2025-11-18 15:38 ` [PATCH v6 0/2] Fix a recently introduced deadlock Jens Axboe
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