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Subject[PATCH] hung_task : check the value of "sysctl_hung_task_timeout_sec"
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 <sdu.liu@huawei.com>
---
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 */
- 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;
}

/*
--
1.8.5.5.dirty

.






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