Re: [PATCH v3 08/16] mm/rmap: drop "compound" parameter from page_add_new_anon_rmap()

[Matthew Wilcox]

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.