linux-kernel - Re: [PATCH] x86/fpu: drop_fpu() should not assume that tsk == current

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Message-ID: <20150309180646.GA14028@redhat.com>
Date:	Mon, 9 Mar 2015 19:06:47 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Borislav Petkov <bp@...e.de>
Cc:	Dave Hansen <dave.hansen@...el.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Pekka Riikonen <priikone@....fi>,
	Rik van Riel <riel@...hat.com>,
	Suresh Siddha <sbsiddha@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	Quentin Casasnovas <quentin.casasnovas@...cle.com>
Subject: Re: [PATCH] x86/fpu: drop_fpu() should not assume that tsk ==
	current

On 03/09, Borislav Petkov wrote:
>
> On Mon, Mar 09, 2015 at 06:10:41PM +0100, Oleg Nesterov wrote:
> > drop_fpu() does clear_used_math() and usually this is correct because
> > tsk == current. However switch_fpu_finish()->restore_fpu_checking() is
> > called before it updates the "current_task" variable. If it fails, we
>
> You mean here "... before __switch_to() updates the current_task ... ",
> I assume?

Yes... should I resend?

Oleg.

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