linux-kernel - [PATCH v2] hung_task : check the value of "sysctl_hung_task_timeout

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Date:	Sun, 23 Mar 2014 15:54:04 +0800
From:	Liu Hua <sdu.liu@...wei.com>
To:	<paul.gortmaker@...driver.com>
CC:	<mingo@...nel.org>, <wangnan0@...wei.com>,
	<linux-kernel@...r.kernel.org>, <peifeiyue@...wei.com>,
	<lizefan@...wei.com>, Liu Hua <sdu.liu@...wei.com>,
	<stable@...r.kernel.org>
Subject: [PATCH v2] 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/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))
+		return MAX_SCHEDULE_TIMEOUT;
+
+	return (timeout * HZ) < MAX_SCHEDULE_TIMEOUT ?
+			timeout * HZ : MAX_SCHEDULE_TIMEOUT;
 }
 
 /*
-- 
1.9.0

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