linux-kernel - [PATCH] hung_task: print more info when reporting the problem

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Date:	Thu, 1 Aug 2013 18:59:41 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	ahecox@...hat.com, Christopher Williams <cww@...hat.com>,
	dwysocha@...hat.com, gavin@...hat.com, Ingo Molnar <mingo@...e.hu>,
	Mandeep Singh Baines <msb@...omium.org>, nshi@...hat.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH] hung_task: print more info when reporting the problem

printk(KERN_ERR) from check_hung_task() likely means the 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@...hat.com>
---
 kernel/hung_task.c |   13 +++++++++----
 1 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 6df6149..3e97fb1 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -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:
@@ -99,10 +100,14 @@ 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\""
-			" disables this message.\n");
+	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);
 
-- 
1.5.5.1


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