From: Pekka Enberg <penberg@kernel.org>
To: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Rientjes <rientjes@google.com>, Tejun Heo <tj@kernel.org>,
Christoph Lameter <cl@linux-foundation.org>,
Matt Mackall <mpm@selenic.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] slub: always align cpu_slab to honor cmpxchg_double requirement
Date: Fri, 3 Jun 2011 08:49:10 +0300 [thread overview]
Message-ID: <BANLkTinjCbhiwRfQ_aN5wtbYipQB6gv5AA@mail.gmail.com> (raw)
In-Reply-To: <4DE7D2AC.1070503@tilera.com>
On Thu, Jun 2, 2011 at 9:13 PM, Chris Metcalf <cmetcalf@tilera.com> wrote:
> On 6/2/2011 1:16 PM, David Rientjes wrote:
>> On Thu, 2 Jun 2011, Chris Metcalf wrote:
>>> On an architecture without CMPXCHG_LOCAL but with DEBUG_VM enabled,
>>> the VM_BUG_ON() in __pcpu_double_call_return_bool() will cause an early
>>> panic during boot unless we always align cpu_slab properly.
>>>
>>> In principle we could remove the alignment-testing VM_BUG_ON() for
>>> architectures that don't have CMPXCHG_LOCAL, but leaving it in means
>>> that new code will tend not to break x86 even if it is introduced
>>> on another platform, and it's low cost to require alignment.
>>>
>>> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
>> Acked-by: David Rientjes <rientjes@google.com>
>>
>>> ---
>>> This needs to be pushed for 3.0 to allow arch/tile to boot.
>>> I'm happy to push it but I assume it would be better coming
>>> from an mm or percpu tree. Thanks!
>>>
>> Should also be marked for stable for 2.6.39.x, right?
>
> No, in 2.6.39 the irqsafe_cpu_cmpxchg_double() was guarded under "#ifdef
> CONFIG_CMPXCHG_LOCAL". Now it's not. I suppose we could take the comment
> change in percpu.h for 2.6.39, but it probably doesn't merit churning the
> stable tree.
Yup. Looks good. Christoph?
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next prev parent reply other threads:[~2011-06-03 5:49 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-02 14:19 Chris Metcalf
2011-06-02 17:16 ` David Rientjes
2011-06-02 18:13 ` Chris Metcalf
2011-06-03 5:49 ` Pekka Enberg [this message]
2011-06-03 14:06 ` Christoph Lameter
2011-06-03 14:33 ` Chris Metcalf
2011-06-03 14:41 ` Christoph Lameter
2011-06-03 18:06 ` Pekka Enberg
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