Commit 48a6d64e authored Oct 11, 2016 by John Siddle Committed by Linus Torvalds Oct 11, 2016

hung_task: allow hung_task_panic when hung_task_warnings is 0

Previously hung_task_panic would not be respected if enabled after
hung_task_warnings had already been decremented to 0.

Permit the kernel to panic if hung_task_panic is enabled after
hung_task_warnings has already been decremented to 0 and another task
hangs for hung_task_timeout_secs seconds.

Check if hung_task_panic is enabled so we don't return prematurely, and
check if hung_task_warnings is non-zero so we don't print the warning
unnecessarily.

[akpm@linux-foundation.org: fix off-by-one]
Link: http://lkml.kernel.org/r/1473450214-4049-1-git-send-email-jsiddle@redhat.com


Signed-off-by: John Siddle <jsiddle@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent e154ccc8

kernel/hung_task.c

+14 −14

Original line number	Diff line number	Diff line
		@@ -98,16 +98,15 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)

		trace_sched_process_hang(t);

		if (!sysctl_hung_task_warnings)
		if (!sysctl_hung_task_warnings && !sysctl_hung_task_panic)
		return;

		if (sysctl_hung_task_warnings > 0)
		sysctl_hung_task_warnings--;

		/*
		* Ok, the task did not get scheduled for more than 2 minutes,
		* complain:
		*/
		if (sysctl_hung_task_warnings) {
		sysctl_hung_task_warnings--;
		pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
		t->comm, t->pid, timeout);
		pr_err(" %s %s %.*s\n",
		@@ -118,6 +117,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
		" disables this message.\n");
		sched_show_task(t);
		debug_show_all_locks();
		}

		touch_nmi_watchdog();

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