On Tue, Jun 12, 2018 at 05:07:37PM +0800, Zhizhou Zhang wrote: > 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 > > Signed-off-by: Zhizhou Zhang <[email protected]> > --- > arch/arm64/kernel/smp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index f3e2e3ae..11b0f30 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -179,7 +179,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) > * 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) > +notrace asmlinkage void secondary_start_kernel(void)
Minor nit: can we please keep asmlinkage first, e.g. asmlinkage notrace void secondary_start_kernel(void) Either way: Acked-by: Mark Rutland <[email protected]> Thanks, Mark. > { > u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK; > struct mm_struct *mm = &init_mm; > -- > 1.9.1 >
