Merge "arm64: defconfig: Enable hung tasks detection"

arch/arm64/configs/vendor/lahaina_debug.config

@@ -18,6 +18,7 @@ CONFIG_EDAC_KRYO_ARM64_PANIC_ON_CE=y
 CONFIG_QMP_DEBUGFS_CLIENT=y
 CONFIG_LKDTM=m
 CONFIG_ATOMIC64_SELFTEST=m
+CONFIG_DETECT_HUNG_TASK=y
 CONFIG_DEBUG_SPINLOCK=y
 CONFIG_TEST_USER_COPY=m
 CONFIG_OF_RESERVED_MEM_CHECK=y

fs/proc/base.c

@@ -2505,7 +2505,7 @@ static struct dentry *proc_pident_instantiate(struct dentry *dentry,
 	return d_splice_alias(inode, dentry);
 }
 
-static struct dentry *proc_pident_lookup(struct inode *dir, 
+static struct dentry *proc_pident_lookup(struct inode *dir,
 					 struct dentry *dentry,
 					 const struct pid_entry *p,
 					 const struct pid_entry *end)
@@ -2692,7 +2692,7 @@ static const struct pid_entry attr_dir_stuff[] = {
 
 static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
 {
-	return proc_pident_readdir(file, ctx, 
+	return proc_pident_readdir(file, ctx,
 				   attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
 }
 
@@ -2855,6 +2855,53 @@ static int proc_tgid_io_accounting(struct seq_file *m, struct pid_namespace *ns,
 }
 #endif /* CONFIG_TASK_IO_ACCOUNTING */
 
+#ifdef CONFIG_DETECT_HUNG_TASK
+static ssize_t proc_hung_task_detection_enabled_read(struct file *file,
+				char __user *buf, size_t count, loff_t *ppos)
+{
+	struct task_struct *task = get_proc_task(file_inode(file));
+	char buffer[PROC_NUMBUF];
+	size_t len;
+	bool hang_detection_enabled;
+
+	if (!task)
+		return -ESRCH;
+	hang_detection_enabled = task->hang_detection_enabled;
+	put_task_struct(task);
+
+	len = scnprintf(buffer, sizeof(buffer), "%d\n", hang_detection_enabled);
+
+	return simple_read_from_buffer(buf, sizeof(buffer), ppos, buffer, len);
+}
+
+static ssize_t proc_hung_task_detection_enabled_write(struct file *file,
+			const char __user *buf, size_t count, loff_t *ppos)
+{
+	struct task_struct *task;
+	bool hang_detection_enabled;
+	int rv;
+
+	rv = kstrtobool_from_user(buf, count, &hang_detection_enabled);
+	if (rv < 0)
+		return rv;
+
+	task = get_proc_task(file_inode(file));
+	if (!task)
+		return -ESRCH;
+	task->hang_detection_enabled = hang_detection_enabled;
+	put_task_struct(task);
+
+	return count;
+}
+
+static const
+struct file_operations proc_hung_task_detection_enabled_operations = {
+	.read		= proc_hung_task_detection_enabled_read,
+	.write		= proc_hung_task_detection_enabled_write,
+	.llseek		= generic_file_llseek,
+};
+#endif
+
 #ifdef CONFIG_SCHED_WALT
 static ssize_t proc_sched_task_boost_read(struct file *file,
 			   char __user *buf, size_t count, loff_t *ppos)
@@ -3234,6 +3281,10 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 	ONE("io",	S_IRUSR, proc_tgid_io_accounting),
 #endif
+#ifdef CONFIG_DETECT_HUNG_TASK
+	REG("hang_detection_enabled", 0666,
+		proc_hung_task_detection_enabled_operations),
+#endif
 #ifdef CONFIG_USER_NS
 	REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
@@ -3634,6 +3685,10 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 	ONE("io",	S_IRUSR, proc_tid_io_accounting),
 #endif
+#ifdef CONFIG_DETECT_HUNG_TASK
+	REG("hang_detection_enabled", 0666,
+		proc_hung_task_detection_enabled_operations),
+#endif
 #ifdef CONFIG_USER_NS
 	REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
 	REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),

include/linux/sched.h

@@ -1076,8 +1076,10 @@ struct task_struct {
 	struct sysv_shm			sysvshm;
 #endif
 #ifdef CONFIG_DETECT_HUNG_TASK
+	/* hung task detection */
 	unsigned long			last_switch_count;
 	unsigned long			last_switch_time;
+	bool hang_detection_enabled;
 #endif
 	/* Filesystem information: */
 	struct fs_struct		*fs;

include/linux/sched/sysctl.h

@@ -12,6 +12,7 @@ extern unsigned int  sysctl_hung_task_panic;
 extern unsigned long sysctl_hung_task_timeout_secs;
 extern unsigned long sysctl_hung_task_check_interval_secs;
 extern int sysctl_hung_task_warnings;
+extern int sysctl_hung_task_selective_monitoring;
 extern int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
 					 void __user *buffer,
 					 size_t *lenp, loff_t *ppos);

kernel/hung_task.c

@@ -23,12 +23,21 @@
 #include <linux/sched/sysctl.h>
 
 #include <trace/events/sched.h>
+#include <linux/sched/sysctl.h>
 
 /*
  * The number of tasks checked:
  */
 int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
 
+/*
+ * Selective monitoring of hung tasks.
+ *
+ * if set to 1, khungtaskd skips monitoring tasks, which has
+ * task_struct->hang_detection_enabled value not set, else monitors all tasks.
+ */
+int sysctl_hung_task_selective_monitoring = 1;
+
 /*
  * Limit number of tasks checked in a batch.
  *
@@ -195,7 +204,10 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
 		}
 		/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
 		if (t->state == TASK_UNINTERRUPTIBLE)
-			check_hung_task(t, timeout);
+			/* Check for selective monitoring */
+			if (!sysctl_hung_task_selective_monitoring ||
+			    t->hang_detection_enabled)
+				check_hung_task(t, timeout);
 	}
  unlock:
 	rcu_read_unlock();

kernel/sysctl.c

@@ -1435,6 +1435,16 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= &neg_one,
 	},
+	{
+		.procname	= "hung_task_selective_monitoring",
+		.data		= &sysctl_hung_task_selective_monitoring,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+
 #endif
 #ifdef CONFIG_RT_MUTEXES
 	{