The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From cb9d7fd51d9fbb329d182423bd7b92d0f8cb0e01 Mon Sep 17 00:00:00 2001
From: Vincent Whitchurch vincent.whitchurch@axis.com Date: Tue, 21 Aug 2018 17:25:07 +0200 Subject: [PATCH] watchdog: Mark watchdog touch functions as notrace
Some architectures need to use stop_machine() to patch functions for ftrace, and the assumption is that the stopped CPUs do not make function calls to traceable functions when they are in the stopped state.
Commit ce4f06dcbb5d ("stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE") added calls to the watchdog touch functions from the stopped CPUs and those functions lack notrace annotations. This leads to crashes when enabling/disabling ftrace on ARM kernels built with the Thumb-2 instruction set.
Fix it by adding the necessary notrace annotations.
Fixes: ce4f06dcbb5d ("stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE") Signed-off-by: Vincent Whitchurch vincent.whitchurch@axis.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: Peter Zijlstra peterz@infradead.org Cc: oleg@redhat.com Cc: tj@kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180821152507.18313-1-vincent.whitchurch@axis.com
diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 5470dce212c0..977918d5d350 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -261,7 +261,7 @@ static void __touch_watchdog(void) * entering idle state. This should only be used for scheduler events. * Use touch_softlockup_watchdog() for everything else. */ -void touch_softlockup_watchdog_sched(void) +notrace void touch_softlockup_watchdog_sched(void) { /* * Preemption can be enabled. It doesn't matter which CPU's timestamp @@ -270,7 +270,7 @@ void touch_softlockup_watchdog_sched(void) raw_cpu_write(watchdog_touch_ts, 0); }
-void touch_softlockup_watchdog(void) +notrace void touch_softlockup_watchdog(void) { touch_softlockup_watchdog_sched(); wq_watchdog_touch(raw_smp_processor_id()); diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c index 1f7020d65d0a..71381168dede 100644 --- a/kernel/watchdog_hld.c +++ b/kernel/watchdog_hld.c @@ -29,7 +29,7 @@ static struct cpumask dead_events_mask; static unsigned long hardlockup_allcpu_dumped; static atomic_t watchdog_cpus = ATOMIC_INIT(0);
-void arch_touch_nmi_watchdog(void) +notrace void arch_touch_nmi_watchdog(void) { /* * Using __raw here because some code paths have diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 60e80198c3df..0280deac392e 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5574,7 +5574,7 @@ static void wq_watchdog_timer_fn(struct timer_list *unused) mod_timer(&wq_watchdog_timer, jiffies + thresh); }
-void wq_watchdog_touch(int cpu) +notrace void wq_watchdog_touch(int cpu) { if (cpu >= 0) per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;