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SubjectRe: [PATCH v2] hung_task : check the value of "sysctl_hung_task_timeout_sec"
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

> + return MAX_SCHEDULE_TIMEOUT;
> +
> + return (timeout * HZ) < MAX_SCHEDULE_TIMEOUT ?
> + timeout * HZ : MAX_SCHEDULE_TIMEOUT;
> }
>
> /*
> --
> 1.9.0
>
> --
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