linux-kernel - [RFC] hung_task:add detecting task in D state milliseconds timeout

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Date:   Thu,  2 Jul 2020 22:08:13 +0800
From:   yang che <chey84736@...il.com>
To:     mcgrof@...nel.org, keescook@...omium.org, yzaikin@...gle.com
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        yang che <chey84736@...il.com>
Subject: [RFC] hung_task:add detecting task in D state milliseconds timeout

current hung_task_check_interval_secs and hung_task_timeout_secs
only supports seconds.in some cases,the TASK_UNINTERRUPTIBLE state
takes less than 1 second.The task of the graphical interface,
the unterruptible state lasts for hundreds of milliseconds
will cause the interface to freeze

echo 1 > /proc/sys/kernel/hung_task_milliseconds
value of hung_task_check_interval_secs and hung_task_timeout_secs whill
to milliseconds

Signed-off-by: yang che <chey84736@...il.com>
---
 include/linux/sched/sysctl.h |  1 +
 kernel/hung_task.c           | 33 +++++++++++++++++++++++++++------
 kernel/sysctl.c              |  9 +++++++++
 3 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index 660ac49..e5e5de2 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -16,6 +16,7 @@ extern unsigned int sysctl_hung_task_all_cpu_backtrace;
 
 extern int	     sysctl_hung_task_check_count;
 extern unsigned int  sysctl_hung_task_panic;
+extern unsigned int  sysctl_hung_task_millisecond;
 extern unsigned long sysctl_hung_task_timeout_secs;
 extern unsigned long sysctl_hung_task_check_interval_secs;
 extern int sysctl_hung_task_warnings;
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index ce76f49..7f34912 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -44,6 +44,14 @@ int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
 unsigned long __read_mostly sysctl_hung_task_timeout_secs = CONFIG_DEFAULT_HUNG_TASK_TIMEOUT;
 
 /*
+ * sysctl_hung_task_milliseconds is enable milliseconds
+ *
+ * if is 1 , hung_task_timeout_secs and hung_task_check_interval_secs will
+ * means set to millisecondsuse. as hung_task_timeout_secs is 5, will 5 milliseconds
+ */
+unsigned int __read_mostly sysctl_hung_task_millisecond;
+
+/*
  * Zero (default value) means use sysctl_hung_task_timeout_secs:
  */
 unsigned long __read_mostly sysctl_hung_task_check_interval_secs;
@@ -108,8 +116,13 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 		t->last_switch_time = jiffies;
 		return;
 	}
-	if (time_is_after_jiffies(t->last_switch_time + timeout * HZ))
-		return;
+	if (sysctl_hung_task_millisecond) {
+		if (time_is_after_jiffies(t->last_switch_time + (timeout * HZ) / 1000))
+			return;
+	} else {
+		if (time_is_after_jiffies(t->last_switch_time + timeout * HZ))
+			return;
+	}
 
 	trace_sched_process_hang(t);
 
@@ -126,8 +139,12 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 	if (sysctl_hung_task_warnings) {
 		if (sysctl_hung_task_warnings > 0)
 			sysctl_hung_task_warnings--;
-		pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
-		       t->comm, t->pid, (jiffies - t->last_switch_time) / HZ);
+		if (sysctl_hung_task_millisecond)
+			pr_err("INFO: task %s:%d blocked for more than %ld milliiseconds.\n",
+				t->comm, t->pid, (jiffies - t->last_switch_time) / HZ * 1000);
+		else
+			pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
+				t->comm, t->pid, (jiffies - t->last_switch_time) / HZ);
 		pr_err("      %s %s %.*s\n",
 			print_tainted(), init_utsname()->release,
 			(int)strcspn(init_utsname()->version, " "),
@@ -217,8 +234,12 @@ static long hung_timeout_jiffies(unsigned long last_checked,
 				 unsigned long timeout)
 {
 	/* timeout of 0 will disable the watchdog */
-	return timeout ? last_checked - jiffies + timeout * HZ :
-		MAX_SCHEDULE_TIMEOUT;
+	if (sysctl_hung_task_millisecond)
+		return timeout ? last_checked - jiffies + (timeout * HZ) / 1000 :
+			MAX_SCHEDULE_TIMEOUT;
+	else
+		return timeout ? last_checked - jiffies + timeout * HZ :
+			MAX_SCHEDULE_TIMEOUT;
 }
 
 /*
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index db1ce7a..0bdcd66 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2476,6 +2476,15 @@ static struct ctl_table kern_table[] = {
 		.extra1		= SYSCTL_ZERO,
 	},
 	{
+		.procname       = "hung_task_milliseconds",
+		.data           = &sysctl_hung_task_millisecond,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec_minmax,
+		.extra1         = SYSCTL_ZERO,
+		.extra2         = SYSCTL_ONE,
+	},
+	{
 		.procname	= "hung_task_timeout_secs",
 		.data		= &sysctl_hung_task_timeout_secs,
 		.maxlen		= sizeof(unsigned long),
-- 
2.7.4