linux-kernel - Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem with fpu state changes

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Date:	Sat, 9 Aug 2008 09:49:25 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Suresh Siddha <suresh.b.siddha@...el.com>,
	Wolfgang Walter <wolfgang.walter@...m.de>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>, viro@...IV.linux.org.uk,
	vegard.nossum@...il.com
Subject: Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem with fpu state changes

On Fri, Aug 08, 2008 at 12:01:15PM -0700, H. Peter Anvin wrote:
>
> It's technically overkill, if (and only if!) these instructions don't 
> actually touch the SSE state (most likely they're using the SSE 
> pipeline, and need this stuff to deal with power management issues.)

Yes the PadLock uses the SSE pipeline, but doesn't touch any
of the state.

> However, overkill is a good way to make sure something is dead. 
> Applying the patch will make sure we fix the regression, and we can 
> worry about optimizing this further post-2.6.27.

Do we really need the FPU changes right now? I'd prefer for that
to be backed out until a proper solution is found.  Disabling
preemption around crypto is really bad for scheduling latency.

Thanks,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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