4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Thomas Gleixner <[email protected]> commit 9bf11ecce5a2758e5a097c2f3a13d08552d0d6f9 upstream. When the dummy timer callback is invoked before the real timer callbacks, then it tries to install that timer for the starting CPU. If the platform does not have a broadcast timer installed the installation fails with a kernel crash. The crash happens due to a unconditional deference of the non available broadcast device. This needs to be fixed in the timer core code. But even when this is fixed in the core code then installing the dummy timer before the real timers is a pointless exercise. Move it to the end of the callback list. Fixes: 00c1d17aab51 ("clocksource/dummy_timer: Convert to hotplug state machine") Reported-and-tested-by: Mason <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Anna-Maria Gleixner <[email protected]> Cc: Richard Cochran <[email protected]> Cc: Sebastian Andrzej Siewior <[email protected]> Cc: Daniel Lezcano <[email protected]> Cc: Peter Zijlstra <[email protected]>, Cc: Sebastian Frias <[email protected]> Cc: Thibaud Cornic <[email protected]> Cc: Robin Murphy <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]> --- include/linux/cpuhotplug.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -80,7 +80,6 @@ enum cpuhp_state { CPUHP_AP_ARM_L2X0_STARTING, CPUHP_AP_ARM_ARCH_TIMER_STARTING, CPUHP_AP_ARM_GLOBAL_TIMER_STARTING, - CPUHP_AP_DUMMY_TIMER_STARTING, CPUHP_AP_JCORE_TIMER_STARTING, CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING, CPUHP_AP_ARM_TWD_STARTING, @@ -94,6 +93,8 @@ enum cpuhp_state { CPUHP_AP_KVM_ARM_VGIC_INIT_STARTING, CPUHP_AP_KVM_ARM_VGIC_STARTING, CPUHP_AP_KVM_ARM_TIMER_STARTING, + /* Must be the last timer callback */ + CPUHP_AP_DUMMY_TIMER_STARTING, CPUHP_AP_ARM_XEN_STARTING, CPUHP_AP_ARM_CORESIGHT_STARTING, CPUHP_AP_ARM_CORESIGHT4_STARTING,
