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Message-ID: <53314552.4000905@huawei.com>
Date: Tue, 25 Mar 2014 16:58:58 +0800
From: Liu hua <sdu.liu@...wei.com>
To: Satoru Takeuchi <satoru.takeuchi@...il.com>
CC: <paul.gortmaker@...driver.com>, <mingo@...nel.org>,
<wangnan0@...wei.com>, <linux-kernel@...r.kernel.org>,
<peifeiyue@...wei.com>, <lizefan@...wei.com>,
<stable@...r.kernel.org>
Subject: Re: [PATCH v2] hung_task : check the value of "sysctl_hung_task_timeout_sec"
δΊ 2014/3/24 4:50, Satoru Takeuchi ει:
> 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: <stable@...r.kernel.org>
>> Signed-off-by: Liu Hua <sdu.liu@...wei.com>
>> ---
>> 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 :
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 <linux/inotify.h>
#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
>
>> + return MAX_SCHEDULE_TIMEOUT;
>> +
>> + return (timeout * HZ) < MAX_SCHEDULE_TIMEOUT ?
>> + timeout * HZ : MAX_SCHEDULE_TIMEOUT;
>> }
>>
>> /*
>> --
>> 1.9.0
>>
>> --
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>
> .
>
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