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'll do some grepping - hopefully this is just a case of exposing the functions/defines that already exist for those architectures. Note that in terms of the new page walking code, these new defines are only used when walking a page table without a VMA (which isn't currently done), so architectures which don't use p?d_large currently will work fine with the generic versions. They only need to provide meaningful definitions when switching to use the walk-without-a-VMA functionality. Thanks for reporting the breakage. Steve
