From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753006AbaCJDer (ORCPT ); Sun, 9 Mar 2014 23:34:47 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:22531 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752821AbaCJDeq (ORCPT ); Sun, 9 Mar 2014 23:34:46 -0400 Message-ID: <531D32BE.2090601@huawei.com> Date: Mon, 10 Mar 2014 11:34:22 +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: Paul Gortmaker , Ingo Molnar CC: , Li Zefan , Wang Nan , Subject: Re: [PATCH] hung_task : check the value of "sysctl_hung_task_timeout_sec" References: <1394089669-18285-1-git-send-email-sdu.liu@huawei.com> <53182182.3080101@huawei.com> <531895C6.9000305@windriver.com> In-Reply-To: <531895C6.9000305@windriver.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit 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 on 2014/3/6 23:35, Paul Gortmaker wrote: > On 14-03-06 02:19 AM, Liu hua wrote: >> As sysctl_hung_task_timeout_sec is unsigned long, when this value is >> larger then LONG_MAX, the function schedule_timeout_interruptible in >> watchdog will return immediately without sleep : >> >> for example (in x86_64 platform): >> >> linux# echo 0xFFFFFFFFFFFFFFFF > /proc/sys/kernel/hung_task_timeout_secs >> >> [ 66.798350] schedule_timeout: wrong timeout value ffffffffffffff06 >> [ 66.800064] schedule_timeout: wrong timeout value ffffffffffffff06 >> [ 66.801774] schedule_timeout: wrong timeout value ffffffffffffff06 >> [ 66.803488] schedule_timeout: wrong timeout value ffffffffffffff06 >> [ 66.805225] schedule_timeout: wrong timeout value ffffffffffffff06 >> >> The screen was filled with "schedule_timeout: wrong timeout value >> ffffffffffffff06" and the system stalled. >> >> So I do some check and correction in timeout_jiffies, to let the function >> schedule_timeout_interruptible allways get the valid parameter. >> >> Signed-off-by: Liu Hua >> --- >> kernel/hung_task.c | 11 ++++++++++- >> 1 file changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/hung_task.c b/kernel/hung_task.c >> index 06bb141..ef96650 100644 >> --- a/kernel/hung_task.c >> +++ b/kernel/hung_task.c >> @@ -186,7 +186,16 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) >> static unsigned long timeout_jiffies(unsigned long timeout) >> { >> /* timeout of 0 will disable the watchdog */ > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > You are breaking the above functionality/feature by declaring > zero invalid. > > Paul. > -- > Actually the patch will disable the watchdog if the timeout is illegal(except 0) for schedule_timeout_interruptible. I will make a new patch that disables the watchdog when the timeout is 0 or above LONG_MAX without printing errors ? What do you think? Liu Hua >> - return timeout ? timeout * HZ : MAX_SCHEDULE_TIMEOUT; >> + if ((timeout == 0) || (timeout > MAX_SCHEDULE_TIMEOUT)) { >> + pr_err("%s : wrong timeout value %lx\n", >> + __func__, timeout); >> + pr_err("Timeout value is set to MAX_SCHEDULE_TIMEOUT(%lx) now.\n", >> + MAX_SCHEDULE_TIMEOUT); >> + return MAX_SCHEDULE_TIMEOUT; >> + } >> + >> + return (timeout * HZ) < MAX_SCHEDULE_TIMEOUT ? >> + timeout * HZ : MAX_SCHEDULE_TIMEOUT; >> } >> >> /* >> > > . >