4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zhizhou Zhang <zhizhouzhang@xxxxxxxxxxxx>
[ Upstream commit b154886f7892499d0d3054026e19dfb9a731df61 ]
We can't call function trace hook before setup percpu offset.
When entering secondary_start_kernel(), percpu offset has not
been initialized. So this lead hotplug malfunction.
Here is the flow to reproduce this bug:
echo 0 > /sys/devices/system/cpu/cpu1/online
echo function > /sys/kernel/debug/tracing/current_tracer
echo 1 > /sys/kernel/debug/tracing/tracing_on
echo 1 > /sys/devices/system/cpu/cpu1/online
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Tested-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Zhizhou Zhang <zhizhouzhang@xxxxxxxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/smp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -131,7 +131,7 @@ static void smp_store_cpu_info(unsigned
* This is the secondary CPU boot entry. We're using this CPUs
* idle thread stack, but a set of temporary page tables.
*/
-asmlinkage void secondary_start_kernel(void)
+asmlinkage notrace void secondary_start_kernel(void)
{
struct mm_struct *mm = &init_mm;
unsigned int cpu = smp_processor_id();
