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Date: Tue, 4 Mar 2008 09:59:10 -0800
From: Suresh Siddha <suresh.b.siddha@intel.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>, hpa@zytor.com,
       tglx@linutronix.de, andi@firstfloor.org, hch@infradead.org,
       linux-kernel@vger.kernel.org, Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: [patch 1/2] x86, fpu: split FPU state from task struct - v3
Message-ID: <20080304175909.GE28006@linux-os.sc.intel.com>
References: <20080303230335.892214000@linux-os.sc.intel.com> <20080304102804.GA17681@elte.hu>
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On Tue, Mar 04, 2008 at 11:28:04AM +0100, Ingo Molnar wrote:
> 
> * Suresh Siddha <suresh.b.siddha@intel.com> wrote:
> 
> > Split the FPU save area from the task struct. This allows easy 
> > migration of FPU context, and it's generally cleaner. It also allows 
> > the following two optimizations:
> 
> hm, i didnt get a reply from you to:
> 
>     http://lkml.org/lkml/2008/3/3/47
> 
> I'm uneasy to apply patches without knowing whether previous problems 
> are fixed. In the changelog there's a mention of:
> 
>   v3: Fixed the non-atomic calling sequence in atomic context.
> 
> is that the same bug?

Yes. Sorry for not pointing out explicitly. Essentially 32bit kernel with
CONFIG_PREEMPT is calling math_state_restore() with interrupts disabled.
Handled this by enabling/disabling the interrupts around the blocking call.
with small code changes ensuring that it is safe to enable/disable interrupts
at this point.

Do you want a v4 or separate patch for handling the kmem_cache_alloc() failure

thanks,
suresh