linux-kernel - [PATCH] hung_task: change sysctl_hung_task_check

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Message-ID: <5233CE5E.7040004@huawei.com>
Date:	Sat, 14 Sep 2013 10:47:58 +0800
From:	Li Zefan <lizefan@...wei.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] hung_task: change sysctl_hung_task_check_count to int

As sysctl_hung_task_check_count is unsigned long, when this value is
assigned to max_count in check_hung_uninterruptible_tasks(), it's
truncated to int type.

Therefore if we write 2^32 to sysctl.hung_task_check_count, hung task
detection will be effectively disabled.

Not a big deal, but still it's better to fix this inconsistency.

Signed-off-by: Li Zefan <lizefan@...wei.com>
---
 include/linux/sched/sysctl.h | 2 +-
 kernel/hung_task.c           | 2 +-
 kernel/sysctl.c              | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index bf8086b..9552afa 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -2,8 +2,8 @@
 #define _SCHED_SYSCTL_H
 
 #ifdef CONFIG_DETECT_HUNG_TASK
+extern int	     sysctl_hung_task_check_count;
 extern unsigned int  sysctl_hung_task_panic;
-extern unsigned long sysctl_hung_task_check_count;
 extern unsigned long sysctl_hung_task_timeout_secs;
 extern unsigned long sysctl_hung_task_warnings;
 extern int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 6df6149..b5a5d42 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -19,7 +19,7 @@
 /*
  * The number of tasks checked:
  */
-unsigned long __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
+int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
 
 /*
  * Limit number of tasks checked in a batch.
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 07f6fc4..5e5cc21 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -962,9 +962,9 @@ static struct ctl_table kern_table[] = {
 	{
 		.procname	= "hung_task_check_count",
 		.data		= &sysctl_hung_task_check_count,
-		.maxlen		= sizeof(unsigned long),
+		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_doulongvec_minmax,
+		.proc_handler	= proc_dointvec_minmax,
 	},
 	{
 		.procname	= "hung_task_timeout_secs",
-- 
1.8.0.2
--
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