On Tue, May 07, 2024 at 09:13:17AM -0700, Christoph Hellwig wrote: > On Tue, May 07, 2024 at 05:11:58PM +0100, Matthew Wilcox wrote: > > > __bio_add_page(bio, page, len, 0); > > > > no? len can be > PAGE_SIZE. > > Yes. So what? the zero_page is only PAGE_SIZE bytes long. so you'd be writing from the page that's after the zero page, whatever contents that has.