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From: Ming Lei <ming.lei@redhat.com>
To: "yukuai (C)" <yukuai3@huawei.com>
Cc: Bart Van Assche <bvanassche@acm.org>,
	axboe@kernel.dk, chaitanya.kulkarni@wdc.com,
	damien.lemoal@wdc.com, dhowells@redhat.com,
	asml.silence@gmail.com, ajay.joshi@wdc.com,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	yi.zhang@huawei.com, zhangxiaoxu5@huawei.com,
	luoshijie1@huawei.com, jan kara <jack@suse.cz>
Subject: Re: [PATCH] block: revert pushing the final release of request_queue to a workqueue.
Date: Mon, 10 Feb 2020 10:32:40 +0800	[thread overview]
Message-ID: <20200210023240.GA10029@ming.t460p> (raw)
In-Reply-To: <f89ae154-d6b7-0a3b-060d-f3131b0c1c1d@huawei.com>

On Mon, Feb 10, 2020 at 10:13:22AM +0800, yukuai (C) wrote:
> On 2020/2/10 9:00, Bart Van Assche wrote:
> > Have you already noticed patch "[PATCH] blktrace: Protect q->blk_trace
> > with RCU"? If not, have you already tried to verify whether that patch
> > fixes the use-after-free detected by syzbot?
> 
> I just tested and confirmed the patch didn't fix the problem.

Right, the two are for fixing different issue.

> 
> By the way, I think Ming is right about "So release not by wq just
> reduces the chance, instead of fixing it completely.", and "move
> blk_mq_debugfs_unregister() into blk_unregister_queue()" is a good
> choice. However, blk_trace_shutdown() and blk_mq_exit_queue() also
> remove some files or dirs, and they may need to move to
> blk_unregister_queue().

Right.

Fortunately, we hold sysfs_dir_lock in blk_unregister_queue(), so
the issue can be fixed by check & remove with holding the same lock
in blk_trace_free().


Thanks, 
Ming


  reply	other threads:[~2020-02-10  2:33 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-06 11:10 [PATCH] block: revert pushing the final release of request_queue to a workqueue yu kuai
2020-02-07  4:09 ` Bart Van Assche
2020-02-07  6:02   ` yukuai (C)
2020-02-07  7:10     ` yukuai (C)
2020-02-07  9:30 ` Ming Lei
2020-02-07 10:26   ` yukuai (C)
2020-02-07 12:24     ` yukuai (C)
2020-02-07 13:04       ` Ming Lei
2020-02-08  6:12         ` yukuai (C)
2020-02-10  1:00 ` Bart Van Assche
2020-02-10  2:13   ` yukuai (C)
2020-02-10  2:32     ` Ming Lei [this message]
2020-02-10  3:14     ` Bart Van Assche
2020-02-10  8:49       ` yukuai (C)

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