Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754625Ab2EGDlQ (ORCPT ); Sun, 6 May 2012 23:41:16 -0400 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:58200 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752874Ab2EGDlP (ORCPT ); Sun, 6 May 2012 23:41:15 -0400 Message-ID: <4FA74089.4080204@linux.vnet.ibm.com> Date: Mon, 07 May 2012 08:54:57 +0530 From: Anshuman Khandual User-Agent: Mozilla/5.0 (X11; Linux i686; rv:11.0) Gecko/20120411 Thunderbird/11.0.1 MIME-Version: 1.0 To: Sameer Nanda CC: mingo@redhat.com, peterz@infradead.org, len.brown@intel.com, pavel@ucw.cz, rjw@sisk.pl, akpm@linux-foundation.org, 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 References: <1335550240-17765-1-git-send-email-snanda@chromium.org> <1335892956-30606-1-git-send-email-snanda@chromium.org> In-Reply-To: <1335892956-30606-1-git-send-email-snanda@chromium.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit x-cbid: 12050617-6102-0000-0000-00000163A4B6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1034 Lines: 22 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. Regards Anshuman -- 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/