From a6d5930ccf3c746fa737b221d42adb6811945eec Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky Date: Thu, 11 Jan 2018 09:53:35 +0900 Subject: [PATCH] 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: Sergey Senozhatsky Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- kernel/workqueue.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index a2dccfe1acec..8365a52a74c5 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -48,6 +48,7 @@ #include #include #include +#include #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(); -- 2.20.1