On Thu, Feb 20, 2025 at 10:02:54AM -0800, Dave Hansen wrote:
> On 2/19/25 22:41, Gwan-gyeong Mun wrote:
> > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> > index 01ea7c6df303..7935859bcc21 100644
> > --- a/arch/x86/mm/init_64.c
> > +++ b/arch/x86/mm/init_64.c
> > @@ -1498,6 +1498,54 @@ static long __meminitdata addr_start, addr_end;
> > static void __meminitdata *p_start, *p_end;
> > static int __meminitdata node_start;
> >
> > +static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
> > +{
> > + void *p = vmemmap_alloc_block(size, node);
> > +
> > + if (!p)
> > + return NULL;
> > + memset(p, 0, size);
> > +
> > + return p;
> > +}
>
> This is a pure copy and paste of the generic function. I assume this is
> because the mm/sparse-vmemmap.c is static. But this kind of copying is
> really unfortunate.
Agreed.
> ...
> > +pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
> > +{
> > + pgd_t *pgd = pgd_offset_k(addr);
> > +
> > + if (pgd_none(*pgd)) {
> > + void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
> > +
> > + if (!p)
> > + return NULL;
> > +
> > + pgd_populate(&init_mm, pgd, p);
> > + sync_global_pgds(addr, addr);
> > + }
> > +
> > + return pgd;
> > +}
>
> I'd _really_ like to find another way to do this. We really don't want
> to add copy-and-paste versions of generic functions that we now need to
> maintain on the x86 side.
>
> The _best_ way is probably to create some p*d_populate_kernel() helpers:
>
> void pgd_populate_kernel(unsigned long addr, pgd_t *pgd, p4d_t *p4d)
> {
> pgd_populate(&init_mm, pgd, p4d);
> arch_sync_global_pgds(addr, addr+something);
> }
>
> and move over most of the callers of:
>
> p*d_populate(&init_mm, ...);
I think this makes more sense, yes.
So for those that do not need the sync, arch_sync_* would be just a
noop, so we could avoid all these code duplication.
--
Oscar Salvador
SUSE Labs
