From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Chen Yu To: Thomas Gleixner 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 References: <1468903861-12487-1-git-send-email-yu.c.chen@intel.com> Message-ID: <578DEDBB.9030602@intel.com> Date: Tue, 19 Jul 2016 17:07:07 +0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: Hi Thomas, On 2016年07月19日 16:36, Thomas Gleixner wrote: > 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 After pm_trace is enabled, during system suspend/hibernate, the hash name of each devices will be written to rtc, so the rtc value depends on what we write in last suspend round, thus pm_trace can be used for diagnose which device failed to suspend(eg, the suspending on this device hang the system, we reboot the system , and check rtc hash value). In our case, after first hibernate/resume round, we found our current system time is at 2117, so syscore_resume -> timekeeping_resume : __timekeeping_inject_sleeptime(tk, &ts_delta) would inject a quite large delta : 2117 - 2017 year, thus the sleep_time_bin is overflow. thanks, Yu