4.18-stable review patch. If anyone has any objections, please let me know.
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From: Vincent Whitchurch vincent.whitchurch@axis.com
commit cb9d7fd51d9fbb329d182423bd7b92d0f8cb0e01 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/watchdog.c | 4 ++-- kernel/watchdog_hld.c | 2 +- kernel/workqueue.c | 2 +- 3 files changed, 4 insertions(+), 4 deletions(-)
--- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -266,7 +266,7 @@ 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 @@ -275,7 +275,7 @@ void touch_softlockup_watchdog_sched(voi 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()); --- 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 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5559,7 +5559,7 @@ static void wq_watchdog_timer_fn(struct 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;