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From: Luis Chamberlain <mcgrof@kernel.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
	axboe@kernel.dk, viro@zeniv.linux.org.uk, bvanassche@acm.org,
	rostedt@goodmis.org, mingo@redhat.com, jack@suse.cz,
	nstange@suse.de, akpm@linux-foundation.org, 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>,
	syzbot+603294af2d01acfdd6da@syzkaller.appspotmail.com
Subject: Re: [PATCH v2 03/10] blktrace: fix debugfs use after free
Date: Fri, 24 Apr 2020 23:47:41 +0000	[thread overview]
Message-ID: <20200424234741.GE11244@42.do-not-panic.com> (raw)
In-Reply-To: <20200422094320.GH299948@T590>

On Wed, Apr 22, 2020 at 05:43:20PM +0800, Ming Lei wrote:
> On Wed, Apr 22, 2020 at 07:28:59AM +0000, Luis Chamberlain wrote:
> > At this point in time patch-wise we still haven't reverted back to
> > synchronous request_queue removal. Considering this, a race with the
> > parent disappearing can happen because the request_queue removal is
> > deferred, that is, the request_queue's kobject's release() call used
> > schedule_work() to finish off its removal. We expect the last
> > blk_put_queue() to be called at the end of blk_cleanup_queue(). Since
> 
> Actually no, we expect that request queue is released after disk is
> released. Don't forget that gendisk does hold one extra refcount of
> request queue.

Then by all means using blk_put_queue() from everywhere should be safe
in atomic context, as we have control over that blk_put_queue() on the
block layer.

(Modulo, we accept the races possible today on blk_get_queue(), which
I'll try to address).

  Luis


  parent reply	other threads:[~2020-04-24 23:47 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-19 19:45 [PATCH v2 00/10] block: fix blktrace debugfs use after free Luis Chamberlain
2020-04-19 19:45 ` [PATCH v2 01/10] block: move main block debugfs initialization to its own file Luis Chamberlain
2020-04-19 21:06   ` Bart Van Assche
2020-04-19 19:45 ` [PATCH v2 02/10] blktrace: move blktrace debugfs creation to helper function Luis Chamberlain
2020-04-19 21:11   ` Bart Van Assche
2020-04-22  7:12   ` Christoph Hellwig
2020-04-19 19:45 ` [PATCH v2 03/10] blktrace: fix debugfs use after free Luis Chamberlain
2020-04-19 21:55   ` Bart Van Assche
2020-04-20  0:04     ` Luis Chamberlain
2020-04-20  0:38       ` Bart Van Assche
2020-04-20 18:46         ` Luis Chamberlain
2020-04-20 20:16   ` Greg KH
2020-04-20 20:41     ` Luis Chamberlain
2020-04-21  7:00       ` Greg KH
2020-04-22  7:28         ` Luis Chamberlain
2020-04-22  9:43           ` Ming Lei
2020-04-22 10:31             ` Luis Chamberlain
2020-04-24 23:47             ` Luis Chamberlain [this message]
2020-04-22  7:29       ` Christoph Hellwig
2020-04-22  7:34         ` Luis Chamberlain
2020-04-22  7:27   ` Christoph Hellwig
2020-04-22  7:48     ` Luis Chamberlain
2020-04-22  8:10       ` Christoph Hellwig
2020-04-22  8:26         ` Luis Chamberlain
2020-04-19 19:45 ` [PATCH v2 04/10] block: revert back to synchronous request_queue removal Luis Chamberlain
2020-04-19 22:23   ` Bart Van Assche
2020-04-20 18:59     ` Luis Chamberlain
2020-04-20 21:11       ` Bart Van Assche
2020-04-20 21:51         ` Luis Chamberlain
2020-04-19 19:45 ` [PATCH v2 05/10] blktrace: upgrade warns to BUG_ON() on unexpected circmunstances Luis Chamberlain
2020-04-19 22:50   ` Bart Van Assche
2020-04-19 23:07     ` Luis Chamberlain
2020-04-20 23:20       ` Steven Rostedt
2020-04-19 19:45 ` [PATCH v2 06/10] blk-debugfs: upgrade warns to BUG_ON() if directory is already found Luis Chamberlain
2020-04-20 11:36   ` Greg KH
2020-04-25 11:43   ` [blk] 90d38c0e30: kernel_BUG_at_block/blk-debugfs.c kernel test robot
2020-04-19 19:45 ` [PATCH v2 07/10] blktrace: move debugfs file creation to its own function Luis Chamberlain
2020-04-19 22:55   ` Bart Van Assche
2020-04-20 11:37     ` Greg KH
2020-04-19 19:45 ` [PATCH v2 08/10] blktrace: add checks for created debugfs files on setup Luis Chamberlain
2020-04-19 22:57   ` Bart Van Assche
2020-04-19 23:05     ` Luis Chamberlain
2020-04-19 23:17       ` Bart Van Assche
2020-04-20 11:40         ` Greg KH
2020-04-20 18:44           ` Luis Chamberlain
2020-04-20 20:11             ` Greg KH
2020-04-20 20:20               ` Luis Chamberlain
2020-04-21  6:55                 ` Greg KH
2020-04-20 11:39   ` Greg KH
2020-04-19 19:45 ` [PATCH v2 09/10] block: panic if block debugfs dir is not created Luis Chamberlain
2020-04-19 23:08   ` Bart Van Assche
2020-04-20 11:38   ` Greg KH
2020-04-19 19:45 ` [PATCH v2 10/10] block: put_device() if device_add() fails Luis Chamberlain
2020-04-19 23:40   ` Bart Van Assche
2020-04-24 22:32     ` Luis Chamberlain
2020-04-25  1:58       ` Bart Van Assche
2020-04-25  2:12         ` Luis Chamberlain
2020-04-19 19:48 ` [PATCH v2 00/10] block: fix blktrace debugfs use after free Luis Chamberlain

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