Re: [PATCH v4 2/9] mm: introduce pgtable_has_pmd_leaves()

[Luiz Capitulino]

On 2026-05-17 08:03, Lance Yang wrote:
> On Wed, May 13, 2026 at 09:52:05PM -0400, Luiz Capitulino wrote:
> [...]
> > > >    
> > > >    #if !defined(MAX_POSSIBLE_PHYSMEM_BITS) && !defined(CONFIG_64BIT)
> > > > diff --git a/init/main.c b/init/main.c
> > > > index 96f93bb06c49..eea7c5bdddf7 100644
> > > > --- a/init/main.c
> > > > +++ b/init/main.c
> > > > @@ -1053,6 +1053,7 @@ void start_kernel(void)
> > > >    	print_kernel_cmdline(saved_command_line);
> > > >    	/* parameters may set static keys */
> > > >    	parse_early_param();
> > > > +	init_arch_has_pmd_leaves();
> > >
> > > Can't we do this a bit later from some mm code?
> > >
> > > This feels like something that can just go somewhere into mm_core_init()?
>
> Indeed. If nobody needs pgtable_has_pmd_leaves() that early, it is
> cleaner to put it in MM init code :)
>
> > Yes, this can be done. My intent in calling it as early as possible was
> > to allow callers to use the API from __setup() handlers if needed, but
> > since we don't have this case in the code today we can put it in
> > mm_core_init() for now.
> >
> > > There, we should probably call this something like XXX_init(), and prepare it
> > > from detecting support for PUD leaves as well.
> > >
> > > Maybe just
> > >
> > > pgtable_init() ?
> >
> > What about pgtable_api_init()? I'm afraid that pgtable_init() might be
> > confused with code doing real page table initialization.
>
> Or what about pgtable_leaf_support_init()? It says what this init is for,
> setting up the cached leaf-support check. Today that only means PMD
> leaves, but the name still works if we add PUD leaves later :)

Yes, I can use that one.