From 6a716c90a51338009c3bc1f460829afaed8f922d Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sat, 19 Oct 2013 18:18:28 +0200 Subject: [PATCH] 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: Oleg Nesterov Cc: Dave Sullivan Cc: Peter Zijlstra Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20131019161828.GA7439@redhat.com Signed-off-by: Ingo Molnar --- include/trace/events/sched.h | 19 +++++++++++++++++++ kernel/hung_task.c | 4 ++++ 2 files changed, 23 insertions(+) diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index 2e7d994..2a652d1 100644 --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -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 */ diff --git a/kernel/hung_task.c b/kernel/hung_task.c index 0422523..8807061 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -16,6 +16,7 @@ #include #include #include +#include /* * 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--; -- 2.7.4