linux-kernel - Re: [PATCH 02 of 11] get_task

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20080507162006.GB18260@duo.random>
Date:	Wed, 7 May 2008 18:20:07 +0200
From:	Andrea Arcangeli <andrea@...ranet.com>
To:	Robin Holt <holt@....com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <clameter@....com>,
	Jack Steiner <steiner@....com>, Nick Piggin <npiggin@...e.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	kvm-devel@...ts.sourceforge.net,
	Kanoj Sarcar <kanojsarcar@...oo.com>,
	Roland Dreier <rdreier@...co.com>,
	Steve Wise <swise@...ngridcomputing.com>,
	linux-kernel@...r.kernel.org, Avi Kivity <avi@...ranet.com>,
	linux-mm@...ck.org, general@...ts.openfabrics.org,
	Hugh Dickins <hugh@...itas.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Anthony Liguori <aliguori@...ibm.com>,
	Chris Wright <chrisw@...hat.com>,
	Marcelo Tosatti <marcelo@...ck.org>,
	Eric Dumazet <dada1@...mosbay.com>,
	"Paul E. McKenney" <paulmck@...ibm.com>
Subject: Re: [PATCH 02 of 11] get_task_mm

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).
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/