Commit 62635ea8 authored by Sergey Senozhatsky's avatar Sergey Senozhatsky Committed by Tejun Heo

workqueue: avoid hard lockups in show_workqueue_state()

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>
Cc: stable@vger.kernel.org # v4.5+
parent 01dfee95
......@@ -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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