From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752438AbcGSIig (ORCPT ); Tue, 19 Jul 2016 04:38:36 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:54460 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751938AbcGSIid (ORCPT ); Tue, 19 Jul 2016 04:38:33 -0400 X-Greylist: delayed 1234 seconds by postgrey-1.27 at vger.kernel.org; Tue, 19 Jul 2016 04:38:32 EDT Date: Tue, 19 Jul 2016 10:36:20 +0200 (CEST) From: Thomas Gleixner To: Chen Yu cc: John Stultz , "Rafael J. Wysock" , Linux PM list , Linux Kernel list , "Stable # 3 . 17+" Subject: Re: [PATCH][v2] timekeeping: Fix memory overwrite of sleep_time_bin array In-Reply-To: <1468903861-12487-1-git-send-email-yu.c.chen@intel.com> Message-ID: References: <1468903861-12487-1-git-send-email-yu.c.chen@intel.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 19 Jul 2016, Chen Yu wrote: > It is reported the hibernation fails at 2nd attempt, which > hangs at hibernate() -> syscore_resume() -> i8237A_resume() > -> claim_dma_lock(), because the lock has already been taken. > However there is actually no other process would like to grab > this lock on that problematic platform. > > Further investigation shows that, the problem is caused by setting > /sys/power/pm_trace to 1 before the 1st hibernation, since once > pm_trace is enabled, the rtc becomes an unmeaningful value after resumed, So why is the RTC value useless if pm_trace is enabled? I really have a hard time to understand why pm_trace would affect the sleep time readout from RTC. Thanks, tglx