On Tue, 2007-11-13 at 23:33 +1100, Nick Piggin wrote: > On Tuesday 13 November 2007 01:30, schwidefsky@xxxxxxxxxx wrote: > > From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> > > > > In order to change the layout of the page tables after an mmap has > > crossed the adress space limit of the current page table layout a > > architecture hook in get_unmapped_area is needed. The arguments > > are the address of the new mapping and the length of it. > > Can you comment what this is supposed to be fore somewhere? This hook is going to be used by the dynamic page table patch for s390: http://marc.info/?l=linux-mm&m=119333667710539&w=2 That patch allows processes to have different number of page table levels, 31 bit processes have 2 levels (2GB), normal 64 bit processes have 3 levels (4TB) and really big 64 bit processes can have 4 levels (8PB). The downgrade of a page table to use less levels than the parent process is done in arch_pick_mmap_layout. The upgrade is done by using the arch_rebalance_pgtables call. I've considered using the arch_get_unmapped_area but got scared by the indirection in get_unmapped_area: get_area = current->mm->get_unmapped_area; if (file && file->f_op && file->f_op->get_unmapped_area) get_area = file->f_op->get_unmapped_area; addr = get_area(file, addr, len, pgoff, flags); -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. - To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
