Commit 41e85ce8 authored Aug 01, 2013 by Oleg Nesterov Committed by Ingo Molnar Aug 02, 2013

hung_task debugging: Print more info when reporting the problem



printk(KERN_ERR) from check_hung_task() likely means we have a bug,
but unlike BUG_ON()/WARN_ON ()it doesn't show the kernel version,
this complicates the bug-reports investigation.

Add the additional pr_err() to print tainted/release/version
like dump_stack_print_info() does, the output becomes:

        INFO: task perl:504 blocked for more than 2 seconds.
	      Not tainted 3.11.0-rc1-10367-g136bb46-dirty #1763
        "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
        ...

While at it, turn the old printk's into pr_err().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: ahecox@redhat.com
Cc: Christopher Williams <cww@redhat.com>
Cc: dwysocha@redhat.com
Cc: gavin@redhat.com
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: nshi@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20130801165941.GA17544@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 2b488397

kernel/hung_task.c

+9 −4

Original line number	Diff line number	Diff line
		@@ -15,6 +15,7 @@
		#include <linux/lockdep.h>
		#include <linux/export.h>
		#include <linux/sysctl.h>
		#include <linux/utsname.h>

		/*
		* The number of tasks checked:
		@@ -99,9 +100,13 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
		* Ok, the task did not get scheduled for more than 2 minutes,
		* complain:
		*/
		printk(KERN_ERR "INFO: task %s:%d blocked for more than "
		"%ld seconds.\n", t->comm, t->pid, timeout);
		printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
		pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
		t->comm, t->pid, timeout);
		pr_err(" %s %s %.*s\n",
		print_tainted(), init_utsname()->release,
		(int)strcspn(init_utsname()->version, " "),
		init_utsname()->version);
		pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
		" disables this message.\n");
		sched_show_task(t);
		debug_show_held_locks(t);

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