From: Bart Van Assche <bvanassche@acm.org>
To: Luis Chamberlain <mcgrof@kernel.org>,
axboe@kernel.dk, viro@zeniv.linux.org.uk,
gregkh@linuxfoundation.org, rostedt@goodmis.org,
mingo@redhat.com, jack@suse.cz, ming.lei@redhat.com,
nstange@suse.de, akpm@linux-foundation.org
Cc: mhocko@suse.com, yukuai3@huawei.com, linux-block@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Omar Sandoval <osandov@fb.com>,
Hannes Reinecke <hare@suse.com>, Michal Hocko <mhocko@kernel.org>
Subject: Re: [RFC v2 5/5] block: revert back to synchronous request_queue removal
Date: Thu, 9 Apr 2020 20:12:21 -0700 [thread overview]
Message-ID: <161e938d-929b-1fdb-ba77-56b839c14b5b@acm.org> (raw)
In-Reply-To: <20200409214530.2413-6-mcgrof@kernel.org>
On 2020-04-09 14:45, Luis Chamberlain wrote:
> blk_put_queue() puts decrements the refcount for the request_queue
^^^^
can this word be left out?
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 8b1cab52cef9..46fee1ef92e3 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -614,6 +614,7 @@ struct request_queue {
> #define QUEUE_FLAG_PCI_P2PDMA 25 /* device supports PCI p2p requests */
> #define QUEUE_FLAG_ZONE_RESETALL 26 /* supports Zone Reset All */
> #define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */
> +#define QUEUE_FLAG_DEFER_REMOVAL 28 /* defer queue removal */
>
> #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
> (1 << QUEUE_FLAG_SAME_COMP))
> @@ -648,6 +649,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
> #else
> #define blk_queue_rq_alloc_time(q) false
> #endif
> +#define blk_queue_defer_removal(q) \
> + test_bit(QUEUE_FLAG_DEFER_REMOVAL, &(q)->queue_flags)
Since blk_queue_defer_removal() has no callers the code that depends on
QUEUE_FLAG_DEFER_REMOVAL to be set will be subject to bitrot. It would
make me happy if the QUEUE_FLAG_DEFER_REMOVAL flag and the code that
depends on that flag would be removed.
Please add a might_sleep() call in blk_put_queue() since with this patch
applied it is no longer allowed to call blk_put_queue() from atomic context.
Thanks,
Bart.
next prev parent reply other threads:[~2020-04-10 3:12 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-09 21:45 [RFC v2 0/5] blktrace: fix use after free Luis Chamberlain
2020-04-09 21:45 ` [RFC v2 1/5] block: move main block debugfs initialization to its own file Luis Chamberlain
2020-04-10 2:48 ` Bart Van Assche
2020-04-09 21:45 ` [RFC v2 2/5] blktrace: fix debugfs use after free Luis Chamberlain
2020-04-10 2:52 ` Bart Van Assche
2020-04-10 19:58 ` Luis Chamberlain
2020-04-11 23:09 ` Bart Van Assche
2020-04-14 3:32 ` Luis Chamberlain
2020-04-09 21:45 ` [RFC v2 3/5] blktrace: ref count the request_queue during ioctl Luis Chamberlain
2020-04-10 2:58 ` Bart Van Assche
2020-04-09 21:45 ` [RFC v2 4/5] mm/swapfile: refcount block and queue before using blkcg_schedule_throttle() Luis Chamberlain
2020-04-10 3:02 ` Bart Van Assche
2020-04-10 14:34 ` Luis Chamberlain
2020-04-09 21:45 ` [RFC v2 5/5] block: revert back to synchronous request_queue removal Luis Chamberlain
2020-04-10 3:12 ` Bart Van Assche [this message]
2020-04-10 14:34 ` Luis Chamberlain
2020-04-10 20:50 ` Luis Chamberlain
2020-04-10 21:27 ` Luis Chamberlain
2020-04-11 23:21 ` Bart Van Assche
2020-04-14 3:38 ` Luis Chamberlain
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