linux-kernel - Re: INFO: task hung in __get

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Date:   Thu, 16 May 2019 14:32:01 +0200
From:   Jan Kara <jack@...e.cz>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     Jan Kara <jack@...e.cz>, Jens Axboe <axboe@...nel.dk>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        syzbot <syzbot+10007d66ca02b08f0e60@...kaller.appspotmail.com>,
        dvyukov@...gle.com, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        linux-block@...r.kernel.org
Subject: Re: INFO: task hung in __get_super

On Thu 16-05-19 21:17:14, Tetsuo Handa wrote:
> On 2019/05/16 20:48, Jan Kara wrote:
> > OK, so non-racy fix was a bit more involved and I've ended up just
> > upgrading the file reference to an exclusive one in loop_set_fd() instead
> > of trying to hand-craft some locking solution. The result is attached and
> > it passes blktests.
> 
> blkdev_get() has corresponding blkdev_put().
> bdgrab() does not have corresponding bdput() ?

Yes, and that's hidden inside blkdev_put() (or failing blkdev_get()). Don't
get me started on calling conventions of these functions... I've wasted half
an hour trying to figure out where I'm leaking inode references in my patch
;).

								Honza

-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR