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Commit a6d5930c authored by Sergey Senozhatsky's avatar Sergey Senozhatsky Committed by Greg Kroah-Hartman
Browse files

workqueue: avoid hard lockups in show_workqueue_state() 



commit 62635ea8c18f0f62df4cc58379e4f1d33afd5801 upstream.

show_workqueue_state() can print out a lot of messages while being in
atomic context, e.g. sysrq-t -> show_workqueue_state(). If the console
device is slow it may end up triggering NMI hard lockup watchdog.

Signed-off-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent edd0a403

kernel/workqueue.c

+13 −0
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ 
#include <linux/nodemask.h>

#include <linux/moduleparam.h>

#include <linux/uaccess.h>

#include <linux/nmi.h>



#include "workqueue_internal.h"
@@ -4479,6 +4480,12 @@ void show_workqueue_state(void) 
			if (pwq->nr_active || !list_empty(&pwq->delayed_works))

				show_pwq(pwq);

			spin_unlock_irqrestore(&pwq->pool->lock, flags);

			/*

			 * We could be printing a lot from atomic context, e.g.

			 * sysrq-t -> show_workqueue_state(). Avoid triggering

			 * hard lockup.

			 */

			touch_nmi_watchdog();

		}

	}
@@ -4506,6 +4513,12 @@ void show_workqueue_state(void) 
		pr_cont("\n");

	next_pool:

		spin_unlock_irqrestore(&pool->lock, flags);

		/*

		 * We could be printing a lot from atomic context, e.g.

		 * sysrq-t -> show_workqueue_state(). Avoid triggering

		 * hard lockup.

		 */

		touch_nmi_watchdog();

	}



	rcu_read_unlock_sched();