workqueue: avoid hard lockups in show_workqueue_state() (62635ea8) · Commits · 戴 / test

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:

Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by:

Tejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org # v4.5+

kernel/workqueue.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -48,6 +48,7 @@
		#include <linux/moduleparam.h>
		#include <linux/uaccess.h>
		#include <linux/sched/isolation.h>
		#include <linux/nmi.h>

		#include "workqueue_internal.h"

		@@ -4463,6 +4464,12 @@ 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();
		}
		}

		@@ -4490,6 +4497,12 @@ 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();

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