linux-kernel - Re: [PATCH 3/3] x86, fpu: kill save_init_fpu(), change math_error() to use unlazy

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Message-ID: <54CAAC1C.1070703@redhat.com>
Date:	Thu, 29 Jan 2015 16:54:36 -0500
From:	Rik van Riel <riel@...hat.com>
To:	Oleg Nesterov <oleg@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>
CC:	Suresh Siddha <sbsiddha@...il.com>,
	Andy Lutomirski <luto@...capital.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] x86, fpu: kill save_init_fpu(), change math_error()
 to use unlazy_fpu()

On 01/29/2015 04:08 PM, Oleg Nesterov wrote:
> math_error() calls save_init_fpu() after conditional_sti(), this means
> that the caller can be preempted. If !use_eager_fpu() we can hit the
> WARN_ON_ONCE(!__thread_has_fpu(tsk)) and/or save the wrong FPU state.
> 
> Change math_error() to use unlazy_fpu() and kill save_init_fpu().
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

Reviewed-by: Rik van Riel <riel@...hat.com>

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