On Thu, Apr 07, 2022 at 02:54:42PM +0100, Matthew Wilcox wrote: > On Thu, Apr 07, 2022 at 02:40:08PM +0800, zhenwei pi wrote: > > size_to_hstate(4K) returns NULL pointer, this leads kernel BUG in > > function page_vma_mapped_walk. > > Yes, I think this is the right fix. It's not immediately obvious from > the bug and the patch, but what's going on is: > > page_mapped_in_vma() sets nr_pages to 1. This is correct because we > usually only want to know about the precise page, and not about the > folio containing it. But hugetlbfs is special (... in so many ways ...) > and actually wants to work on the entire folio. We could set nr_pages > specially for hugetlb pages, but it's better to ignore it in > page_vma_mapped_walk() for the hugetlb case. > > I'll fix up the changelog and add it to my pile of fixes that I'm > sending tomorrow. > https://git.infradead.org/users/willy/pagecache.git/shortlog/refs/heads/for-next I looked over the patch in context, and realised we now don't need to call size_to_hstate since we're getting the hstate from the VMA. https://git.infradead.org/users/willy/pagecache.git/commitdiff/98ea02597b9967c0817d29fee2f96d21b9e59ca5
