Jason Gunthorpe wrote: > On Fri, Apr 12, 2024 at 04:55:31PM +1000, Alistair Popple wrote: > > > Ok, I think I found the dragons you were talking about earlier for > > device-dax. I completely broke that because as you've already pointed > > out pmd_trans_huge() won't filter out DAX pages. That's fine for FS DAX > > (because the pages are essentially normal pages now anyway), but we > > don't have a PMD equivalent of vm_normal_page() which leads to all sorts > > of issues for DEVDAX. > > What about vm_normal_page() depends on the radix level ? > > Doesn't DEVDAX memory have struct page too? Yes. > > So I will probably have to add something like that unless we only need > > to support large (pmd/pud) mappings of DEVDAX pages on systems with > > CONFIG_ARCH_HAS_PTE_SPECIAL in which case I guess we could just filter > > based on pte_special(). > > pte_special should only be used by memory without a struct page, is > that what DEVDAX is? Right, I don't think pte_special is applicable for any DAX pages.
