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Date: Fri, 19 Dec 2008 08:14:40 -0800
From: Greg KH <gregkh@suse.de>
To: Pavel Machek <pavel@suse.cz>
Cc: linux-kernel@vger.kernel.org, stable@kernel.org,
       Justin Forbes <jmforbes@linuxtx.org>,
       Zwane Mwaikambo <zwane@arm.linux.org.uk>,
       "Theodore Ts'o" <tytso@mit.edu>, Randy Dunlap <rdunlap@xenotime.net>,
       Dave Jones <davej@redhat.com>, Chuck Wolber <chuckw@quantumlinux.com>,
       Chris Wedgwood <reviews@ml.cw.f00f.org>,
       Michael Krufky <mkrufky@linuxtv.org>, Chuck Ebbert <cebbert@redhat.com>,
       Domenico Andreoli <cavokz@gmail.com>, Willy Tarreau <w@1wt.eu>,
       Rodrigo Rubira Branco <rbranco@la.checkpoint.com>,
       Jake Edge <jake@lwn.net>, Eugene Teo <eteo@redhat.com>,
       torvalds@linux-foundation.org, akpm@linux-foundation.org,
       alan@lxorguk.ukuu.org.uk, Joerg Roedel <joerg.roedel@amd.com>
Subject: Re: [patch 01/22] AMD IOMMU: enable device isolation per default
Message-ID: <20081219161440.GB12492@suse.de>
References: <20081216235704.347182084@mini.kroah.org> <20081217000353.GB4504@kroah.com> <20081218130015.GA1420@ucw.cz>
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On Thu, Dec 18, 2008 at 02:00:15PM +0100, Pavel Machek wrote:
> On Tue 2008-12-16 16:03:53, Greg KH wrote:
> > 2.6.27-stable review patch.  If anyone has any objections, please let us know.
> > 
> > ------------------
> > 
> > From: Joerg Roedel <joerg.roedel@amd.com>
> > 
> > commit 3ce1f93c6d53c3f91c3846cf66b018276c8ac2e7 upstream.
> > 
> > Impact: makes device isolation the default for AMD IOMMU
> > 
> > Some device drivers showed double-free bugs of DMA memory while testing
> > them with AMD IOMMU. If all devices share the same protection domain
> > this can lead to data corruption and data loss. Prevent this by putting
> > each device into its own protection domain per default.
> > 
> > Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
> 
> This does not look like 'fix for a serious bug' to
> me. stable_kernel_rules.txt says '...not a "this could be a problem"
> type thing'.

This is a serious bug, loosing data and crashing drivers seems serious
to me.  There was at least one bug report about this problem, and the
change is upstream and simple and obvious.

thanks,

greg k-h