On Fri, Feb 12, 2016 at 10:42:09AM -0800, Dave Hansen wrote: > On 02/11/2016 06:21 AM, Kirill A. Shutemov wrote: > > File pmds can be safely skip on copy_huge_pmd(), we can re-fault them > > later. COW for file mappings handled on pte level. > > Is this different from 4k pages? I figured we might skip copying > file-backed ptes on fork, but I couldn't find the code.
Currently, we only filter out on per-VMA basis. See first comment in copy_page_range(). Here we handle PMD mapped file pages in COW mapping. File THP can be mapped into COW mapping as result of read page fault. -- Kirill A. Shutemov
