Confusion about __do_fault and MM_ANONPAGES

Hi, I have some confusion about when is anon=1 when __do_fault is called. __do_fault seems to be called only when the page fault is of a linear or a non-linear mapping. My understanding is neither of these can be anonymous, so I am confused about the below code fragment: In which case is anon=1 when memory.c::__do_fault is called? In __do_fault, you'll see something like... if (anon) { inc_mm_counter_fast(mm, MM_ANONPAGES); page_add_new_anon_rmap(page, vma, address); } else { Thanks! Joel