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>>>> 2) allow callers of alloc_page*() to change page_type from NotRmappable >>>> to other types. >>> >>> Could we instead just set the special type in vm_insert_page(), after >>> verifying that it does not have any other type? >> >> You mean in validate_page_before_insert() we set the page to NotRmappable >> if it can be inserted, then in the rmap code we reject NotRmappable >> page/folios? And NotRmappable will remain until the page/folio is freed. >> That should work. So the purpose is to avoid setting the page_type if >> a page/folio is never going through vm_insert_page()? > > Yes, only these non-folio pages will show up process page tables. > > We would add a safety check that the mapcount really is 0 (-1) or > already the proper type (NotRmappable). > > Rmap code would then simply skip any such thing. OK, I can give this a try in my new version. Best Regards, Yan, Zi