Date: Wed, 4 May 2011 19:12:20 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Ingo Molnar <mingo@elte.hu>
cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>, Tejun Heo <tj@kernel.org>,
        Pekka Enberg <penberg@kernel.org>, Jens Axboe <axboe@kernel.dk>,
        Andrew Morton <akpm@linux-foundation.org>, werner <w.landgraf@ru.ru>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [block IO crash] Re: 2.6.39-rc5-git2 boot crashs
In-Reply-To: <20110504165021.GA1404@elte.hu>
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On Wed, 4 May 2011, Ingo Molnar wrote:

> 
> * Linus Torvalds <torvalds@linux-foundation.org> wrote:
> 
> > My gut reaction would be: let's do the minimal patch that just fixes things 
> > to do irqsafe_cpu_cmpxchg_double() for 2.6.39, and then let's remove the 
> > #ifdef'fery in -rc1. [...]
> 
> Looks like the sanest option IMHO, -rc7 is pretty late for anything than a 
> few-liner patch.

Agreed.
 
> > [...] Or make _really_ sure that things are ok for platforms that never even 
> > triggered the CMPXCHG_LOCAL case before.
> 
> Considering that the status quo was !CMPXCHG_LOCAL in v2.6.38 and that lockless 
> SLUB is an x86-only affair right now:
> 
>  $ git grep CMPXCHG_LOCAL arch/
>  arch/um/Kconfig.x86:config CMPXCHG_LOCAL
>  arch/x86/Kconfig.cpu:config CMPXCHG_LOCAL
> 
> There should be no problem with other architectures, right?

No, they use the local_irq disabled path which is pretty much the same
as in 38.

Thanks,

	tglx
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