Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964894Ab2FHVou (ORCPT ); Fri, 8 Jun 2012 17:44:50 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34955 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934508Ab2FHVot (ORCPT ); Fri, 8 Jun 2012 17:44:49 -0400 Date: Fri, 8 Jun 2012 14:44:47 -0700 From: Andrew Morton To: Anshuman Khandual Cc: Sameer Nanda , mingo@redhat.com, peterz@infradead.org, len.brown@intel.com, pavel@ucw.cz, rjw@sisk.pl, dzickus@redhat.com, msb@chromium.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, olofj@chromium.org, "Srivatsa S. Bhat" Subject: Re: [PATCH v2] watchdog: fix for lockup detector breakage on resume Message-Id: <20120608144447.b8e2d146.akpm@linux-foundation.org> In-Reply-To: <4FA74089.4080204@linux.vnet.ibm.com> References: <1335550240-17765-1-git-send-email-snanda@chromium.org> <1335892956-30606-1-git-send-email-snanda@chromium.org> <4FA74089.4080204@linux.vnet.ibm.com> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1288 Lines: 28 On Mon, 07 May 2012 08:54:57 +0530 Anshuman Khandual wrote: > On Tuesday 01 May 2012 10:52 PM, Sameer Nanda wrote: > > > On the suspend/resume path the boot CPU does not go though an > > offline->online transition. This breaks the NMI detector > > post-resume since it depends on PMU state that is lost when > > the system gets suspended. > > > We should not have allowed the PMU to go with events counting on it across the suspend/resume transition > and find out that the state has been lost. This patch solves the problem of the NMI detector as we restart the > counter again when the boot cpu comes back online during resume. But the original cause (PMU going with > counters into the suspend state) which triggered this problem is still there. May be we should have called > perf_event_exit() on the boot cpu before going into the suspend state. > That sounds like a nicer solution. An implementation would be nice ;) I'll keep the original patch on life support until we get all this nailed down. -- 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/