Matthew Wilcox <wi...@infradead.org> writes: > On Wed, Jan 16, 2019 at 07:57:03AM +0100, Michal Hocko wrote: >> On Wed 16-01-19 11:51:32, Anshuman Khandual wrote: >> > All architectures have been defining their own PGALLOC_GFP as (GFP_KERNEL | >> > __GFP_ZERO) and using it for allocating page table pages. This causes some >> > code duplication which can be easily avoided. GFP_KERNEL allocated and >> > cleared out pages (__GFP_ZERO) are required for page tables on any given >> > architecture. This creates a new generic GFP flag flag which can be used >> > for any page table page allocation. Does not cause any functional change. >> > >> > GFP_PGTABLE is being added into include/asm-generic/pgtable.h which is the >> > generic page tabe header just to prevent it's potential misuse as a general >> > allocation flag if included in include/linux/gfp.h. >> >> I haven't reviewed the patch yet but I am wondering whether this is >> really worth it without going all the way down to unify the common code >> and remove much more code duplication. Or is this not possible for some >> reason? > > Exactly what I suggested doing in response to v1. > > Also, the approach taken here is crazy. x86 has a feature that no other > architecture has bothered to implement yet -- accounting page tables > to the process.
powerpc does __GFP_ACCOUNT for user page tables too. Shamelessly cribbed from the x86 version of course :) cheers
