From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <ming.lei@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Bart.VanAssche@wdc.com, dvyukov@google.com,
linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
jthumshirn@suse.de, alan.christopher.jenkins@gmail.com,
syzbot+c4f9cebf9d651f6e54de@syzkaller.appspotmail.com,
martin.petersen@oracle.com, dan.j.williams@intel.com, hch@lst.de,
oleksandr@natalenko.name, martin@lichtvoll.de, hare@suse.com,
syzkaller-bugs@googlegroups.com, ross.zwisler@linux.intel.com,
keith.busch@intel.com, linux-ext4@vger.kernel.org
Subject: Re: INFO: task hung in blk_queue_enter
Date: Fri, 1 Jun 2018 22:31:13 -0600 [thread overview]
Message-ID: <f43465cf-e2f1-807f-d283-89033c056b5b@kernel.dk> (raw)
In-Reply-To: <20180602023622.GA2306@ming.t460p>
On 6/1/18 8:36 PM, Ming Lei wrote:
>> clear the bit when we need to, potentially even adding a debug check to
>> blk_queue_enter_live() that complains if the ref was not already
>> elevated. Though that would be expensive, compared to the percpu inc
>> now. Not saying the bit is necessarily the best way forward, but I do
>> like it a LOT more than adding an argument to generic_make_request.
>
> We may introduce generic_make_request_with_ref() for blk_queue_split(),
> what do you think of the following patch?
Functionally it'll work as well.
> In DM or MD, there is the following use case:
>
> 1) bio comes from fs, then one clone is made from this bio
>
> 2) the cloned bio is submitted via generic_make_request() from
> another context, such as wq.
>
> 3) then the flag of BIO_QUEUE_ENTERED is inherited and causes
> the queue usage counter isn't held.
We don't copy flags on a clone.
--
Jens Axboe
next prev parent reply other threads:[~2018-06-02 4:31 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-28 11:24 INFO: task hung in blk_queue_enter syzbot
2018-05-15 11:45 ` Tetsuo Handa
2018-05-16 13:05 ` Tetsuo Handa
2018-05-16 14:56 ` Bart Van Assche
2018-05-16 14:56 ` Bart Van Assche
2018-05-16 15:16 ` Dmitry Vyukov
2018-05-16 15:16 ` Dmitry Vyukov
2018-05-16 15:37 ` Bart Van Assche
2018-05-16 15:37 ` Bart Van Assche
2018-05-16 15:37 ` Bart Van Assche
2018-05-21 21:52 ` Tetsuo Handa
2018-05-22 11:20 ` Tetsuo Handa
2018-06-01 10:10 ` Tetsuo Handa
2018-06-01 17:52 ` Jens Axboe
2018-06-01 23:49 ` Ming Lei
2018-06-02 0:49 ` Jens Axboe
2018-06-02 0:56 ` Jens Axboe
2018-06-02 2:36 ` Ming Lei
2018-06-02 4:31 ` Jens Axboe [this message]
2018-06-02 4:54 ` Ming Lei
2018-06-02 8:07 ` Martin Steigerwald
2018-06-02 8:07 ` Martin Steigerwald
2018-06-02 13:48 ` Jens Axboe
2018-06-02 13:48 ` Jens Axboe
2018-06-05 0:27 ` Tetsuo Handa
2018-06-05 0:41 ` Ming Lei
2018-06-07 3:29 ` Ming Lei
2018-06-07 3:29 ` Ming Lei
2018-06-07 13:19 ` Tetsuo Handa
2018-06-04 11:46 ` Dmitry Vyukov
2018-06-04 13:13 ` Tetsuo Handa
2018-05-16 17:33 ` Alan Jenkins
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