From: Luis Chamberlain <mcgrof@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>, Dan Carpenter <error27@gmail.com>,
Christoph Hellwig <hch@lst.de>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH block/for-6.2-fixes] block: Drop spurious might_sleep() from blk_put_queue()
Date: Fri, 6 Jan 2023 12:45:12 -0800 [thread overview]
Message-ID: <Y7iIWA6h88cYjhcO@bombadil.infradead.org> (raw)
In-Reply-To: <Y7iFwjN+XzWvLv3y@slm.duckdns.org>
On Fri, Jan 06, 2023 at 10:34:10AM -1000, Tejun Heo wrote:
> Dan reports the following smatch detected the following:
>
> block/blk-cgroup.c:1863 blkcg_schedule_throttle() warn: sleeping in atomic context
>
> caused by blkcg_schedule_throttle() calling blk_put_queue() in an
> non-sleepable context.
>
> blk_put_queue() acquired might_sleep() in 63f93fd6fa57 ("block: mark
> blk_put_queue as potentially blocking") which transferred the might_sleep()
> from blk_free_queue().
>
> blk_free_queue() acquired might_sleep() in e8c7d14ac6c3 ("block: revert back
> to synchronous request_queue removal") while turning request_queue removal
> synchronous. However, this isn't necessary as nothing in the free path
> actually requires sleeping.
>
> It's pretty unusual to require a sleeping context in a put operation and
> it's not needed in the first place. Let's drop it.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Reported-by: Dan Carpenter <error27@gmail.com>
> Link: https://lkml.kernel.org/r/Y7g3L6fntnTtOm63@kili
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Fixes: e8c7d14ac6c3 ("block: revert back to synchronous request_queue removal") # v5.9+
*tons* has changed since e8c7d14ac6c3 and so the bots might think that
*if* this patch is applied upstream it is justified for older kernels
and I don't think that's yet been verified and doubt it.
And so I think adding a "Fixes" tag is not appropriate here.
First I'd like to hear from Christoph if he agrees with this patch
upstream. For stable, someone would have to do the homework.
Luis
next prev parent reply other threads:[~2023-01-06 20:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Y7g3L6fntnTtOm63@kili>
2023-01-06 17:33 ` [bug report] memcontrol: schedule throttling if we are congested Tejun Heo
2023-01-06 18:49 ` Jens Axboe
2023-01-06 19:09 ` Luis Chamberlain
2023-01-06 20:34 ` [PATCH block/for-6.2-fixes] block: Drop spurious might_sleep() from blk_put_queue() Tejun Heo
2023-01-06 20:45 ` Luis Chamberlain [this message]
2023-01-06 20:47 ` Tejun Heo
2023-01-06 20:52 ` Jens Axboe
2023-01-07 8:36 ` Dan Carpenter
2023-01-08 17:49 ` Christoph Hellwig
2023-01-09 3:30 ` Jens Axboe
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