Re: [PATCH] x86/mm/pti: in pti_clone_pgtable() don't increase addr by PUD_SIZE

[Dave Hansen]

On 8/20/19 7:14 AM, Song Liu wrote:
>> *But*, that shouldn't get hit on a Skylake CPU since those have PCIDs
>> and shouldn't have a global kernel image.  Could you confirm whether
>> PCIDs are supported on this CPU?
> Yes, pcid is listed in /proc/cpuinfo. 

So what's going on?  Could you confirm exactly which pti_clone_pgtable()
is causing you problems?  Do you have a theory as to why this manifests
as a performance problem rather than a functional one?

A diff of these:

	/sys/kernel/debug/page_tables/current_user
	/sys/kernel/debug/page_tables/current_kernel

before and after your patch might be helpful.