From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753928AbbCISIy (ORCPT <rfc822;w@1wt.eu>);
	Mon, 9 Mar 2015 14:08:54 -0400
Received: from mx1.redhat.com ([209.132.183.28]:51766 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751400AbbCISIx (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Mon, 9 Mar 2015 14:08:53 -0400
Date: Mon, 9 Mar 2015 19:06:47 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>, Ingo Molnar <mingo@kernel.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Pekka Riikonen <priikone@iki.fi>, Rik van Riel <riel@redhat.com>,
        Suresh Siddha <sbsiddha@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "Yu, Fenghua" <fenghua.yu@intel.com>,
        Quentin Casasnovas <quentin.casasnovas@oracle.com>
Subject: Re: [PATCH] x86/fpu: drop_fpu() should not assume that tsk ==
	current
Message-ID: <20150309180646.GA14028@redhat.com>
References: <54F74F59.5070107@intel.com> <20150309171041.GB11388@redhat.com> <20150309174825.GH12732@pd.tnic>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20150309174825.GH12732@pd.tnic>
User-Agent: Mutt/1.5.18 (2008-05-17)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

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.