From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755008AbcEXJFK (ORCPT ); Tue, 24 May 2016 05:05:10 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:56792 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754911AbcEXJFG (ORCPT ); Tue, 24 May 2016 05:05:06 -0400 Date: Tue, 24 May 2016 11:04:55 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mgalbraith@suse.de, ahh@google.com, bsegall@google.com, torvalds@linux-foundation.org, matt@codeblueprint.co.uk, morten.rasmussen@arm.com, pjt@google.com, pkondeti@infradead.org, tglx@linutronix.de, byungchul.park@lge.com, mingo@kernel.org, rgkernel@gmail.com Subject: Re: Bisection: Lost wakeups from b5179ac70de8 Message-ID: <20160524090455.GF3192@twins.programming.kicks-ass.net> References: <20160523140410.GA26287@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160523140410.GA26287@linux.vnet.ibm.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 Mon, May 23, 2016 at 07:04:10AM -0700, Paul E. McKenney wrote: > Hello, Peter, > > Current mainline doesn't do well with RCU torture testing, and the > symptom once again looks like lost wakeups. Thankfully, this time each > run takes only about an hour, and the false-positive/-negative rate > is negligible. This means that for the first time ever, "git bisect" > actually did something useful for me. The first bad commit is: > > b5179ac70de8 ("sched/fair: Prepare to fix fairness problems on migration"). > Yeah, we have a patch for that.. I'll go writes a Changelog for it and put it to sched/urgent. See lkml.kernel.org/r/20160523091907.GD15728@worktop.ger.corp.intel.com