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. With this fix, it will still truncate the user input, but reading sysctl.hung_task_check_count reflects the truncated value. v2: limit lowest value to 0. Signed-off-by: Li Zefan <[email protected]> Acked-by: Ingo Molnar <[email protected]> --- include/linux/sched/sysctl.h | 2 +- kernel/hung_task.c | 2 +- kernel/sysctl.c | 5 +++-- 3 files changed, 5 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 3e97fb1..0422523 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -20,7 +20,7 @@ /* * 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 7453418..bcb35ab 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -962,9 +962,10 @@ 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, + .extra1 = &zero, }, { .procname = "hung_task_timeout_secs", -- 1.8.0.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
