Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757662Ab3CNMjk (ORCPT ); Thu, 14 Mar 2013 08:39:40 -0400 Received: from mail-la0-f49.google.com ([209.85.215.49]:42575 "EHLO mail-la0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755943Ab3CNMjh (ORCPT ); Thu, 14 Mar 2013 08:39:37 -0400 MIME-Version: 1.0 In-Reply-To: <20130314091342.GB1377@redhat.com> References: <1363196663-4258-1-git-send-email-fweisbec@gmail.com> <20130314071427.GB7869@gmail.com> <20130314091342.GB1377@redhat.com> Date: Thu, 14 Mar 2013 13:39:35 +0100 Message-ID: Subject: Re: [GIT PULL] sched: Cputime update for 3.10 From: Frederic Weisbecker To: Stanislaw Gruszka , Ingo Molnar Cc: LKML , Steven Rostedt , Peter Zijlstra , Andrew Morton Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 937 Lines: 20 2013/3/14 Stanislaw Gruszka : > On Thu, Mar 14, 2013 at 08:14:27AM +0100, Ingo Molnar wrote: >> Hm, is this a new bug? When was it introduced and is upstream affected as >> well? > > Commit 0cf55e1ec08bb5a22e068309e2d8ba1180ab4239 start to use scalling > for whole thread group, so increase chances of hitting multiplication > overflow, depending on how many CPUs are on the system. Yeah, it was introduced with that commit. Although problems was there back when we started scaling cputime against precise sched runtime. But certainly that commit 0cf55e1ec08bb5a22e068309e2d8ba1180ab4239 made the bug visible and happening in practice. And indeed upstream is affected. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/