On Fri, Mar 01, 2019 at 01:49:53PM +0200, Mike Rapoport wrote: > Hi Kirill, > > On Thu, Feb 21, 2019 at 05:57:06PM +0300, Kirill A. Shutemov wrote: > > On Thu, Feb 21, 2019 at 02:46:18PM +0000, Steven Price wrote: > > > On 21/02/2019 14:28, Kirill A. Shutemov wrote: > > > > On Thu, Feb 21, 2019 at 11:34:52AM +0000, Steven Price wrote: > > > >> From: James Morse <james.morse@xxxxxxx> > > > >> > > > >> Exposing the pud/pgd levels of the page tables to walk_page_range() means > > > >> we may come across the exotic large mappings that come with large areas > > > >> of contiguous memory (such as the kernel's linear map). > > > >> > > > >> For architectures that don't provide p?d_large() macros, provided a > > > >> does nothing default. > > > > > > > > Nak, sorry. > > > > > > > > Power will get broken by the patch. It has pmd_large() inline function, > > > > that will be overwritten by the define from this patch. > > > > > > > > I believe it requires more ground work on arch side in general. > > > > All architectures that has huge page support has to provide these helpers > > > > (and matching defines) before you can use it in a generic code. > > > > > > Sorry about that, I had compile tested on power, but obviously not the > > > right config to actually see the breakage. > > > > I don't think you'll catch it at compile-time. It would silently override > > the helper with always-false. > > Can you explain why the compiler would override the helper define in, e.g. > arch/powerpc/include/asm/pgtable.h with the generic (0)? This one will not be overrided, but the other one will. See arch/powerpc/include/asm/book3s/64/pgtable.h -- Kirill A. Shutemov
