On Sat, Jun 27, 2020 at 08:03:04PM +0100, Matthew Wilcox wrote: > On Sat, Jun 27, 2020 at 05:34:49PM +0300, Mike Rapoport wrote: > > More elaborate versions on arm64 and x86 account memory for the user page > > tables and call to pgtable_pmd_page_ctor() as the part of PMD page > > initialization. > > > > Move the arm64 version to include/asm-generic/pgalloc.h and use the generic > > version on several architectures. > > > > The pgtable_pmd_page_ctor() is a NOP when ARCH_ENABLE_SPLIT_PMD_PTLOCK is > > not enabled, so there is no functional change for most architectures except > > of the addition of __GFP_ACCOUNT for allocation of user page tables. > > Thanks for including this line; it reminded me that we're not setting > the PageTable flag on the page, nor accounting it to the zone page stats. > Hope you don't mind me tagging a patch to do that on as 9/8. > > We could also do with a pud_page_[cd]tor and maybe even p4d/pgd versions. > But that brings me to the next question -- could/should some of this > be moved over to asm-generic/pgalloc.h? The ctor/dtor aren't called > from anywhere else, and there's value to reducing the total amount of > code in mm.h, but then there's also value to keeping all the ifdef > ARCH_ENABLE_SPLIT_PMD_PTLOCK code together too. So I'm a bit torn. > What do you think?
There are arhcitectures that don't use asm-generic/pgalloc.h but rather have their own, sometimes completely different, versoins of these funcitons. I've tried adding linux/pgalloc.h, but I've ended up with contradicting need to include asm/pgalloc.h before the generic code for some architecures or after the generic code for others :) I think let's leave it in mm.h for now, maybe after several more cleaups we could do better. -- Sincerely yours, Mike.