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Commit 6a716c90 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar
Browse files

hung_task debugging: Add tracepoint to report the hang 



Currently check_hung_task() prints a warning if it detects the
problem, but it is not convenient to watch the system logs if
user-space wants to be notified about the hang.

Add the new trace_sched_process_hang() into check_hung_task(),
this way a user-space monitor can easily wait for the hang and
potentially resolve a problem.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: Dave Sullivan <dsulliva@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20131019161828.GA7439@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 4c4e4f61

include/trace/events/sched.h

+19 −0
Original line number Diff line number Diff line
@@ -424,6 +424,25 @@ TRACE_EVENT(sched_pi_setprio, 
			__entry->oldprio, __entry->newprio)

);



#ifdef CONFIG_DETECT_HUNG_TASK

TRACE_EVENT(sched_process_hang,

	TP_PROTO(struct task_struct *tsk),

	TP_ARGS(tsk),



	TP_STRUCT__entry(

		__array( char,	comm,	TASK_COMM_LEN	)

		__field( pid_t,	pid			)

	),



	TP_fast_assign(

		memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN);

		__entry->pid = tsk->pid;

	),



	TP_printk("comm=%s pid=%d", __entry->comm, __entry->pid)

);

#endif /* CONFIG_DETECT_HUNG_TASK */



#endif /* _TRACE_SCHED_H */



/* This part must be outside protection */

kernel/hung_task.c

+4 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/export.h>

#include <linux/sysctl.h>

#include <linux/utsname.h>

#include <trace/events/sched.h>



/*

 * The number of tasks checked:
@@ -92,6 +93,9 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) 
		t->last_switch_count = switch_count;

		return;

	}



	trace_sched_process_hang(t);



	if (!sysctl_hung_task_warnings)

		return;

	sysctl_hung_task_warnings--;