On Thu, Jun 13, 2019 at 01:57:30PM +0000, Song Liu wrote: > > And I'm not convinced that it belongs here at all. User requested PMD > > split and it is done after split_huge_pmd(). The rest can be handled by > > the caller as needed. > > I put this part here because split_huge_pmd() for file-backed THP is > not really done after split_huge_pmd(). And I would like it done before > calling follow_page_pte() below. Maybe we can still do them here, just > for file-backed THPs? > > If we would move it, shall we move to callers of follow_page_mask()? > In that case, we will probably end up with similar code in two places: > __get_user_pages() and follow_page(). > > Did I get this right? Would it be enough to replace pte_offset_map_lock() in follow_page_pte() with pte_alloc_map_lock()? This will leave bunch not populated PTE entries, but it is fine: they will be populated on the next access to them. -- Kirill A. Shutemov
