linux-kernel - Re: [PATCH] slab: fix the DEADLOCK issue on l3 alien lock

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Message-ID: <CAOJsxLFA1sk4KZkRuPL_giktSkFK_g7w-mGi_OEQ9fVXF2UVzw@mail.gmail.com>
Date:	Sat, 8 Sep 2012 11:39:14 +0300
From:	Pekka Enberg <penberg@...nel.org>
To:	paulmck@...ux.vnet.ibm.com
Cc:	Michael Wang <wangyun@...ux.vnet.ibm.com>,
	Christoph Lameter <cl@...ux.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
	Matt Mackall <mpm@...enic.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] slab: fix the DEADLOCK issue on l3 alien lock

On Fri, Sep 7, 2012 at 1:29 AM, Paul E. McKenney
<paulmck@...ux.vnet.ibm.com> wrote:
> On Thu, Sep 06, 2012 at 11:05:11AM +0800, Michael Wang wrote:
>> On 09/05/2012 09:55 PM, Christoph Lameter wrote:
>> > On Wed, 5 Sep 2012, Michael Wang wrote:
>> >
>> >> Since the cachep and cachep->slabp_cache's l3 alien are in the same lock class,
>> >> fake report generated.
>> >
>> > Ahh... That is a key insight into why this occurs.
>> >
>> >> This should not happen since we already have init_lock_keys() which will
>> >> reassign the lock class for both l3 list and l3 alien.
>> >
>> > Right. I was wondering why we still get intermitted reports on this.
>> >
>> >> This patch will invoke init_lock_keys() after we done enable_cpucache()
>> >> instead of before to avoid the fake DEADLOCK report.
>> >
>> > Acked-by: Christoph Lameter <cl@...ux.com>
>>
>> Thanks for your review.
>>
>> And add Paul to the cc list(my skills on mailing is really poor...).
>
> Tested-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>

I'd also like to tag this for the stable tree to avoid bogus lockdep
reports. How far back in release history should we queue this?
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