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From: Andrew Morton <akpm@digeo.com>
To: Hugh Dickins <hugh@veritas.com>
Cc: jsherman@stuy.edu, linux-kernel@vger.kernel.org
Subject: Re: [OOPS] 2.5.63 - NULL pointer dereference in loop device
Date: Wed, 26 Feb 2003 02:52:16 -0800	[thread overview]
Message-ID: <20030226025216.114d4f2c.akpm@digeo.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0302252059370.1430-100000@localhost.localdomain>

Hugh Dickins <hugh@veritas.com> wrote:
>
> On Mon, 24 Feb 2003, Jonah Sherman wrote:
> 
> > I have come across a bug in the loop driver.  To reproduce this bug,
> > simply do:
> ...
> I can't reproduce this, and I don't understand it: please help me!

Well I can't make it happen either now.  It went pop first time I tried it
yesterday.

That being said, I can still trigger it by mmapping /dev/loop0 MAP_SHARED and
dirtying it all.  That triggers the problematic PF_MEMALLOC path much more easily.

	mem=256M
	losetup /dev/loop0 /dev/hda5
	usemem  -m 300 -f /dev/loop0
	<oops>

(gdb) p/x lo->lo_flags
$3 = 0x0

Userspace is passing in lo_encrypt_type == 0, so loop_init_xfer() never calls the transfer
init function.


  parent reply	other threads:[~2003-02-26 10:41 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-02-24 21:25 Jonah Sherman
2003-02-25  5:45 ` Andrew Morton
2003-02-25 21:15 ` Hugh Dickins
2003-02-25 19:38   ` Jonah Sherman
2003-02-26 13:32     ` Hugh Dickins
2003-02-26 10:52   ` Andrew Morton [this message]
2003-02-26 13:55     ` Hugh Dickins

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