From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752076AbaCZH63 (ORCPT ); Wed, 26 Mar 2014 03:58:29 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:49457 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750792AbaCZH61 (ORCPT ); Wed, 26 Mar 2014 03:58:27 -0400 Message-ID: <5332884A.8030904@huawei.com> Date: Wed, 26 Mar 2014 15:56:58 +0800 From: Liu hua User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.0.1 MIME-Version: 1.0 To: Satoru Takeuchi CC: , , , , , , Subject: Re: [PATCH v2] hung_task : check the value of "sysctl_hung_task_timeout_sec" References: <1395561244-69173-1-git-send-email-sdu.liu@huawei.com> <87eh1s3ahp.wl%satoru.takeuchi@gmail.com> <53314552.4000905@huawei.com> <871txqz1mg.wl%satoru.takeuchi@gmail.com> In-Reply-To: <871txqz1mg.wl%satoru.takeuchi@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.111.58.238] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 于 2014/3/26 0:25, Satoru Takeuchi 写道: > At Tue, 25 Mar 2014 16:58:58 +0800, > Liu hua wrote: >> >> 于 2014/3/24 4:50, Satoru Takeuchi 写道: >>> At Sun, 23 Mar 2014 15:54:04 +0800, >>> Liu Hua wrote: >>>> >>>> As sysctl_hung_task_timeout_sec is unsigned long, when this value is >>>> larger then LONG_MAX/HZ, the function schedule_timeout_interruptible in >>>> watchdog will return immediately without sleep and with print : >>>> >>>> [ 205.452934] schedule_timeout: wrong timeout value ffffffffffffff83 >>>> >>>> and then the funtion watchdog will call schedule_timeout_interruptible again >>>> and again. The screen will be filled with >>>> "schedule_timeout: wrong timeout value ffffffffffffff83" >>>> >>>> This patch does some check and correction in timeout_jiffies, to let the >>>> function schedule_timeout_interruptible allways get the valid parameter. >>>> >>>> Cc: >>>> Signed-off-by: Liu Hua >>>> --- >>>> kernel/hung_task.c | 8 ++++++-- >>>> 1 file changed, 6 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/kernel/hung_task.c b/kernel/hung_task.c >>>> index 6df6149..f992286 100644 >>>> --- a/kernel/hung_task.c >>>> +++ b/kernel/hung_task.c >>>> @@ -174,8 +174,12 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) >>>> >>>> static unsigned long timeout_jiffies(unsigned long timeout) >>>> { >>>> - /* timeout of 0 will disable the watchdog */ >>>> - return timeout ? timeout * HZ : MAX_SCHEDULE_TIMEOUT; >>>> + /* timeout of 0 or >= LONG_MAX/HZ will disable the watchdog */ >>>> + if ((timeout == 0) || (timeout > MAX_SCHEDULE_TIMEOUT)) >>> >>> You should check whether sysctl_hung_task_timeout_sec > MAX_SCHEDULE_TIMEOUT/HZ >>> or not when setting this parameter instead. Then this check ins't necessary here. >>> >>> # Just FYI, MAX_SCHEDULE_TIMEOUT should be MAX_SCHEDULE_TIMEOUT/HZ here. >>> >>> Thanks, >>> Satoru >> >> Yes, how about this : > > I confirmed the followings. > > - 3.14-rc8: system hunged up with "hung_task_timeout_secs > LONG_MAX/HZ". > - 3.14-rc8 with your patch: works fine. I can't set the above mentioned value any more. > > Writing possible values (0..LONG_MAX/HZ) in Documentation/sysctl/kernel.txt > make this patch better. > > Thanks, > Satoru Thanks to you attention and suggestion. I remade this patch as following. Is it appropriate to be reposted with tag "PATCH v3" Subject: [PATCH v3] hung_task : check the value of "sysctl_hung_task_timeout_sec" As sysctl_hung_task_timeout_sec is unsigned long, when this value is larger then LONG_MAX/HZ, the function schedule_timeout_interruptible in watchdog will return immediately without sleep and with print : [ 205.452934] schedule_timeout: wrong timeout value ffffffffffffff83 and then the funtion watchdog will call schedule_timeout_interruptible again and again. The screen will be filled with "schedule_timeout: wrong timeout value ffffffffffffff83" This patch does some check and correction in sysctl, to let the function schedule_timeout_interruptible allways get the valid parameter. Signed-off-by: Liu Hua Tested-by: Satoru Takeuchi --- Documentation/sysctl/kernel.txt | 1 + kernel/sysctl.c | 6 ++++++ 2 files changed, 7 insertions(+) diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index e55124e..855d9b3 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -317,6 +317,7 @@ for more than this value report a warning. This file shows up if CONFIG_DETECT_HUNG_TASK is enabled. 0: means infinite timeout - no checking done. +Possible values to set are in range {0..LONG_MAX/HZ}. ============================================================== diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 49e13e1..aae21e8 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -144,6 +144,11 @@ static int min_percpu_pagelist_fract = 8; static int ngroups_max = NGROUPS_MAX; static const int cap_last_cap = CAP_LAST_CAP; +/*this is needed for proc_doulongvec_minmax of sysctl_hung_task_timeout_secs */ +#ifdef CONFIG_DETECT_HUNG_TASK +static unsigned long hung_task_timeout_max = (LONG_MAX/HZ); +#endif + #ifdef CONFIG_INOTIFY_USER #include #endif @@ -995,6 +1000,7 @@ static struct ctl_table kern_table[] = { .maxlen = sizeof(unsigned long), .mode = 0644, .proc_handler = proc_dohung_task_timeout_secs, + .extra2 = &hung_task_timeout_max, }, { .procname = "hung_task_warnings", -- 1.9.0 Thanks, Liu Hua