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Date: Sat, 17 Dec 2011 23:38:57 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>, Andrew Morton <akpm@linux-foundation.org>,
        Kay Sievers <kay.sievers@vrfy.org>, Namhyung Kim <namhyung@gmail.com>,
        Lukas Czerner <lczerner@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] loop: fput() called in loop_clr_fd() may cause bd_mutex
 recursive locking
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On Sun, Dec 18, 2011 at 02:20:53AM +0300, Sergey Senozhatsky wrote:

> > IOW, we have to prevent such setups anyway and not just because of
> > problems on close() - they would be deadly on read() and write()...
> > 
> 
> Preventing recursion in the first place? For example, in lo_open()?

Uh?  No, in loop_set_fd(), where we decide what loop devices will be
backed by what - the code I quoted to you upthread.