From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759812AbcHENxQ (ORCPT ); Fri, 5 Aug 2016 09:53:16 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:51613 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753776AbcHENxP (ORCPT ); Fri, 5 Aug 2016 09:53:15 -0400 Date: Fri, 5 Aug 2016 15:53:08 +0200 From: Peter Zijlstra To: Sebastian Andrzej Siewior Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, Borislav Petkov , Andy Lutomirski , Rik van Riel , Mel Gorman Subject: Re: [PATCH] x86/mm: disable preemption during CR3 read+write Message-ID: <20160805135308.GT6879@twins.programming.kicks-ass.net> References: <1470404259-26290-1-git-send-email-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1470404259-26290-1-git-send-email-bigeasy@linutronix.de> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 05, 2016 at 03:37:39PM +0200, Sebastian Andrzej Siewior wrote: > diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h > index 4e5be94e079a..1ee065954e24 100644 > --- a/arch/x86/include/asm/tlbflush.h > +++ b/arch/x86/include/asm/tlbflush.h > @@ -135,7 +135,14 @@ static inline void cr4_set_bits_and_update_boot(unsigned long mask) > > static inline void __native_flush_tlb(void) > { > + /* > + * if current->mm == NULL then we borrow a mm which may change during a > + * task switch and therefore we must not be preempted while we write CR3 > + * back. > + */ > + preempt_disable(); > native_write_cr3(native_read_cr3()); > + preempt_enable(); > } Acked-by: Peter Zijlstra (Intel)