From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrea Arcangeli <andrea@qumranet.com>
Subject: [ofa-general] Re: [PATCH 02 of 11] get_task_mm
Date: Wed, 7 May 2008 18:20:07 +0200
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Cc: Nick Piggin <npiggin@suse.de>, Chris Wright <chrisw@redhat.com>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>, kvm-devel@lists.sourceforge.net,
	Kanoj Sarcar <kanojsarcar@yahoo.com>, Roland Dreier <rdreier@cisco.com>,
	Jack Steiner <steiner@sgi.com>, linux-kernel@vger.kernel.org,
	Avi Kivity <avi@qumranet.com>, Marcelo Tosatti <marcelo@kvack.org>,
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	Eric Dumazet <dada1@cosmosbay.com>, Christoph Lameter <clameter@sgi.com>
To: Robin Holt <holt@sgi.com>
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On Wed, May 07, 2008 at 10:59:48AM -0500, Robin Holt wrote:
> You can drop this patch.
> 
> This turned out to be a race in xpmem.  It "appeared" as if it were a
> race in get_task_mm, but it really is not.  The current->mm field is
> cleared under the task_lock and the task_lock is grabbed by get_task_mm.

100% agreed, I'll nuke it as it seems really a noop.

> I have been testing you v15 version without this patch and not
> encountere the problem again (now that I fixed my xpmem race).

Great. About your other deadlock I'm curious if my deadlock fix for
the i_mmap_sem patch helped. That was crashing kvm with a VM 2G in the
swap + a swaphog allocating and freeing another 2G of swap in a
loop. I couldn't reproduce any other problem with KVM since I fixed
that bit regardless if I apply only mmu-notifier-core (2.6.26 version)
or the full patchset (post 2.6.26).