From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [PATCH 01/13] powerpc: Add rcu_read_lock() to gup_fast() implementation Date: Thu, 08 Apr 2010 16:31:43 -0400 Message-ID: <4BBE3D2F.6030609@redhat.com> References: <20100408191737.296180458@chello.nl> <20100408192722.643778654@chello.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:23179 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933486Ab0DHUdB (ORCPT ); Thu, 8 Apr 2010 16:33:01 -0400 In-Reply-To: <20100408192722.643778654@chello.nl> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: Andrea Arcangeli , Avi Kivity , Thomas Gleixner , Ingo Molnar , akpm@linux-foundation.org, Linus Torvalds , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Benjamin Herrenschmidt , David Miller , Hugh Dickins , Mel Gorman , Nick Piggin On 04/08/2010 03:17 PM, Peter Zijlstra wrote: > The powerpc page table freeing relies on the fact that IRQs hold off > an RCU grace period, this is currently true for all existing RCU > implementations but is not an assumption Paul wants to support. > > Therefore, also take the RCU read lock along with disabling IRQs to > ensure the RCU grace period does at least cover these lookups. > > Requested-by: Paul E. McKenney > Signed-off-by: Peter Zijlstra > Cc: Nick Piggin > Cc: Benjamin Herrenschmidt Reviewed-by: Rik van Riel