lkml.org 
[lkml]   [2020]   [Jun]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 4/8] asm-generic: pgalloc: provide generic pmd_alloc_one() and pmd_free_one()
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.

\
 
 \ /
  Last update: 2020-06-28 09:11    [W:0.094 / U:0.148 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site