Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752221AbaLTVQb (ORCPT ); Sat, 20 Dec 2014 16:16:31 -0500 Received: from mail-qc0-f180.google.com ([209.85.216.180]:56885 "EHLO mail-qc0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751169AbaLTVQa (ORCPT ); Sat, 20 Dec 2014 16:16:30 -0500 MIME-Version: 1.0 In-Reply-To: References: <20141218051327.GA31988@redhat.com> <1418918059.17358.6@mail.thefacebook.com> <20141218161230.GA6042@redhat.com> <20141219024549.GB1671@redhat.com> <20141219035859.GA20022@redhat.com> <20141219040308.GB20022@redhat.com> <20141219145528.GC13404@redhat.com> Date: Sat, 20 Dec 2014 13:16:29 -0800 X-Google-Sender-Auth: OfthiEW1RH-YX4BS3-EjgtnxDA8 Message-ID: Subject: Re: frequent lockups in 3.18rc4 From: Linus Torvalds To: Thomas Gleixner Cc: Dave Jones , Chris Mason , Mike Galbraith , Ingo Molnar , Peter Zijlstra , =?UTF-8?Q?D=C3=A2niel_Fraga?= , Sasha Levin , "Paul E. McKenney" , Linux Kernel Mailing List , Suresh Siddha , Oleg Nesterov , Peter Anvin Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Dec 20, 2014 at 10:25 AM, Linus Torvalds wrote: > > How/where is the HPET overflow case handled? I don't know the code enough. Hmm, ok, I've re-acquainted myself with it. And I have to admit that I can't see anything wrong. The whole "update_wall_clock" and the shadow timekeeping state is confusing as hell, but seems fine. We'd have to avoid update_wall_clock for a *long* time for overflows to occur. And the overflow in 32 bits isn't that special, since the only thing that really matters is the overflow of "cycle_now - tkr->cycle_last" within the mask. So I'm not seeing anything even halfway suspicious. Linus -- 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/