On Mon, 26 Jun 2023 at 08:50, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > Linus, please merge the MM updates for the 6.5-rc cycle. > [...] > merge conflict in mm/gup.c, vs block tree: > https://lkml.kernel.org/r/20230616115856.3ce7682c@xxxxxxxxxxxxxxxx Hmm. I think this merge resolution in -next is wrong. It now does a common folio = try_get_folio(page, refs); if (flags & FOLL_GET) return folio; for both FOLL_GET and FOLL_PIN, and then *after* that for the FOLL_PIN case it does that /* * Don't take a pin on the zero page - it's not going anywhere * and it is used in a *lot* of places. */ if (is_zero_page(page)) return page_folio(page); but by then it has already done the try_get_folio(). End result: it has already updated refcounts, despite the comment saying not to do that. So I think it needs to match the comment (and the try_grab_page() logic), and just basically if (flags & FOLL_GET) return try_get_folio(page, refs); if (is_zero_page(page)) return page_folio(page); folio = try_get_folio(page, refs); if (!folio) return NULL; instead. That's what my resolution is going to do, but let's add others to the participants list just in case somebody goes "No, Linus, the reason -next does that is XYZ"... Linus
