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hung_task: check the value of "sysctl_hung_task_timeout_sec"

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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 :

  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 <sdu.liu@huawei.com>
Tested-by: Satoru Takeuchi <satoru.takeuchi@gmail.com>
Cc: <stable@vger.kernel.org>	[3.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Liu Hua 2014-04-07 15:38:57 -07:00 committed by Linus Torvalds
parent 2aaf308b95
commit 80df284765
2 changed files with 7 additions and 0 deletions
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1
Documentation/sysctl/kernel.txt
View File

@ -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}.
==============================================================

6
kernel/sysctl.c
View File

@ -141,6 +141,11 @@ 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
@ -985,6 +990,7 @@ 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",