Axel, On Thu, Apr 22, 2021 at 01:22:02PM -0700, Axel Rasmussen wrote: > > + if (page_in_cache) > > + page_add_file_rmap(page, false); > > + else > > + page_add_new_anon_rmap(page, dst_vma, dst_addr, false); > > + > > + /* > > + * Must happen after rmap, as mm_counter() checks mapping (via > > + * PageAnon()), which is set by __page_set_anon_rmap(). > > + */ > > + inc_mm_counter(dst_mm, mm_counter(page)); > > Actually, I've noticed that this is still slightly incorrect. > > As Hugh pointed out, this works for the anon case, because > page_add_new_anon_rmap() sets page->mapping. > > But for the page_in_cache case, it doesn't work: unlike its anon > counterpart, page_add_file_rmap() *does not* set page->mapping. If it's already in the page cache, shouldn't it be set already in e.g. one previous call to shmem_add_to_page_cache()? Thanks, -- Peter Xu
