On Mon, 27 Nov 2017, Peter Zijlstra wrote: > On Mon, Nov 27, 2017 at 11:49:09AM +0100, Ingo Molnar wrote: > > diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c > > index 7b348cc33e2d..f4f4ab8525bd 100644 > > --- a/arch/x86/kernel/cpu/common.c > > +++ b/arch/x86/kernel/cpu/common.c > > @@ -1515,7 +1515,7 @@ EXPORT_PER_CPU_SYMBOL(__preempt_count); > > * the top of the kernel stack. Use an extra percpu variable to track the > > * top of the kernel stack directly. > > */ > > -DEFINE_PER_CPU(unsigned long, cpu_current_top_of_stack) = > > +DEFINE_PER_CPU_USER_MAPPED(unsigned long, cpu_current_top_of_stack) = > > (unsigned long)&init_thread_union + THREAD_SIZE; > > EXPORT_PER_CPU_SYMBOL(cpu_current_top_of_stack); > > I can't find where we would access this one without already having > switched to kernel CR3. > > A kernel with this entire patch reverted seems to boot for me.
Yes, it's not longer required.
