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SubjectRe: [PATCH v2] hung_task : check the value of "sysctl_hung_task_timeout_sec"
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: <stable@vger.kernel.org>
> >> Signed-off-by: Liu Hua <sdu.liu@huawei.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 :

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

>
> 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
> >>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe stable" in
> >> the body of a message to majordomo@vger.kernel.org
> >> More majordomo info at http://vger.kernel.org/majordomo-info.html
> >
> > .
> >
>
>


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