From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752688AbaCFKvk (ORCPT ); Thu, 6 Mar 2014 05:51:40 -0500 Received: from merlin.infradead.org ([205.233.59.134]:51081 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752487AbaCFKvi (ORCPT ); Thu, 6 Mar 2014 05:51:38 -0500 Date: Thu, 6 Mar 2014 11:51:31 +0100 From: Peter Zijlstra To: Fernando Luis =?iso-8859-1?Q?V=E1zquez?= Cao Cc: Linus Torvalds , Andrew Morton , Ingo Molnar , StevenRostedt , linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched/clock: prevent tracing recursion in sched_clock_cpu() Message-ID: <20140306105131.GK9987@twins.programming.kicks-ass.net> References: <1394083528.4524.3.camel@nexus> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1394083528.4524.3.camel@nexus> 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 Thu, Mar 06, 2014 at 02:25:28PM +0900, Fernando Luis Vázquez Cao wrote: > From: Fernando Luis Vazquez Cao > > Prevent tracing of preempt_disable/enable() in sched_clock_cpu(). > When CONFIG_DEBUG_PREEMPT is enabled, preempt_disable/enable() are > traced and this causes trace_clock() users (and probably others) to > go into an infinite recursion. Systems with a stable sched_clock() > are not affected. > > This problem is similar to that fixed by upstream commit 95ef1e52922 > ("KVM guest: prevent tracing recursion with kvmclock"). > > Cc: Linus Torvalds > Cc: Andrew Morton > Cc: Ingo Molnar > Cc: Steven Rostedt > Signed-off-by: Fernando Luis Vazquez Cao Thanks!