On 13.04.22 14:26, Matthew Wilcox wrote: > On Tue, Apr 12, 2022 at 11:37:09AM +0200, David Hildenbrand wrote: >> On 12.04.22 10:47, Vlastimil Babka wrote: >>> There's a VM_BUG_ON_PAGE(PageTransCompound(page), page); later in a >>> !compound branch. Since compound is now determined by the same check, could >>> be deleted. >> >> Yes, eventually we could get rid of both VM_BUG_ON_PAGE() on both >> branches and add a single VM_BUG_ON_PAGE(PageTail(page), page) check on >> the compound branch. (we could also make sure that we're not given a >> hugetlb page) > > As a rule of thumb, if you find yourself wanting to add > VM_BUG_ON_PAGE(PageTail(page), page), you probably want to change the > interface to take a folio. Yeah, I had the same in mind. Might be a reasonable addon on top -- although it would stick out in the rmap code a bit because most functions deal with both, folios and subpages. -- Thanks, David / dhildenb
