From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 01/13] powerpc: Add rcu_read_lock() to gup_fast() implementation Date: Wed, 14 Apr 2010 15:51:50 +0200 Message-ID: <1271253110.32749.47.camel@laptop> References: <20100408191737.296180458@chello.nl> <20100408192722.643778654@chello.nl> <1271120731.13059.6.camel@pasglop> <20100413034311.GB2772@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:58213 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757426Ab0DOH3p (ORCPT ); Thu, 15 Apr 2010 03:29:45 -0400 Received: from e35131.upc-e.chello.nl ([213.93.35.131] helo=dyad.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.69 #1 (Red Hat Linux)) id 1O2JWC-0002K4-9S for linux-arch@vger.kernel.org; Thu, 15 Apr 2010 07:29:44 +0000 In-Reply-To: <20100413034311.GB2772@linux.vnet.ibm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: paulmck@linux.vnet.ibm.com Cc: Benjamin Herrenschmidt , Andrea Arcangeli , Avi Kivity , Thomas Gleixner , Rik van Riel , Ingo Molnar , akpm@linux-foundation.org, Linus Torvalds , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, David Miller , Hugh Dickins , Mel Gorman , Nick Piggin On Mon, 2010-04-12 at 20:43 -0700, Paul E. McKenney wrote: > > So we might have to support the interrupt assumption, at least in some > > form, with those guys... > > One way to make the interrupt assumption official is to use > synchronize_sched() rather than synchronize_rcu(). Well, call_rcu_sched() then, because the current usage is to use call_rcu() to free the page directories. Paul, here is a call_rcu_sched() available in kernel/rcutree.c, but am I right in reading that code that that would not be available for preemptible RCU?