From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752869AbaIJSws (ORCPT ); Wed, 10 Sep 2014 14:52:48 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:38282 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751720AbaIJSwr (ORCPT ); Wed, 10 Sep 2014 14:52:47 -0400 Date: Wed, 10 Sep 2014 20:52:38 +0200 From: Peter Zijlstra To: Andi Kleen Cc: Andi Kleen , linux-kernel@vger.kernel.org, mingo@kernel.org, eranian@google.com, tglx@linutronix.de Subject: Re: [PATCH] perf, x86: Fall back to vmalloc for BTS buffer allocation Message-ID: <20140910185238.GS6758@twins.programming.kicks-ass.net> References: <1410307401-12401-1-git-send-email-andi@firstfloor.org> <20140910075722.GL6758@twins.programming.kicks-ass.net> <20140910144012.GI4120@two.firstfloor.org> <20140910163556.GE4783@worktop.ger.corp.intel.com> <20140910165848.GA11901@worktop.ger.corp.intel.com> <20140910182744.GJ5387@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140910182744.GJ5387@tassilo.jf.intel.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 10, 2014 at 11:27:44AM -0700, Andi Kleen wrote: > > Note that since then we have actually fixed the 'cannot fault from NMI > > context' thing, so we should be able to actually take those faults. I > > suspect we can simply remove those WARNs from the vmalloc fault path, > > but it would need double checking to see if there's no other reasons. > > I think we actually need to use vmalloc_sync_all, because the PEBS/DS > microcode may do the first access, and those lose events when > the page is not present. You'll need to convince Linus: https://lkml.org/lkml/2010/7/14/478