How to access user process memory/pages from swap_pager.c

[Yoshihiro Ota]

Hi,

I'm trying to get some data / statistics for pages being swapped out.

I'm trying to access pages being swapped out in swp_pager_putpages.
Given I have access to vm_page_t, it looked like I would be able to use VM_PAGE_TO_PHYS() to access user pages.

However, I get page-fault panics like:
panic: vm_fault_hold: fault on nofault entry, addr: 0

Which functions/setup do I need to access/copy user data being swapped?

Thanks,
Hiro