On Thu, Mar 01, 2018 at 03:44:12PM +0300, Kirill A. Shutemov wrote: > On Thu, Mar 01, 2018 at 08:17:50AM +0100, Martin Schwidefsky wrote: > > Yeah, that is a nasty bit of code. On s390 we have 2K page tables (pte) > > but 4K pages. If we use full pages for the pte tables we waste 2K of > > memory for each of the tables. So we allocate 4K and split it into two > > 2K pieces. Now we have to keep track of the pieces to be able to free > > them again. > > Have you considered to use slab for page table allocation instead? > IIRC some architectures practice this already.
You're not allowed to do that any more. Look at pgtable_page_ctor(), or rather ptlock_init().
