Re: [PATCH v1 06/11] mm/sparse-vmemmap: refactor vmemmap_populate_basepages()

[Dan Williams <dan.j.williams@intel.com>]

I suspect it's a good sign I'm only finding cosmetic and changelog
changes in the review... I have some more:

A year for now if I'm tracking down a problem and looking through mm
commits I would appreciate a subject line like the following:
"refactor core of vmemmap_populate_basepages() to helper" that gives
an idea of the impact and side effects of the change.

On Thu, Mar 25, 2021 at 4:10 PM Joao Martins <joao.m.martins@oracle.com> wrote:
>

I would add a lead in phrase like: "In preparation for describing a
memmap with compound pages, move the actual..."

> Move the actual pte population logic into a separate function
> vmemmap_populate_address() and have vmemmap_populate_basepages()
> walk through all base pages it needs to populate.

Aside from the above, looks good.

>
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> ---
>  mm/sparse-vmemmap.c | 44 ++++++++++++++++++++++++++------------------
>  1 file changed, 26 insertions(+), 18 deletions(-)
>
> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
> index 370728c206ee..8814876edcfa 100644
> --- a/mm/sparse-vmemmap.c
> +++ b/mm/sparse-vmemmap.c
> @@ -216,33 +216,41 @@ pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
>         return pgd;
>  }
>
> -int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
> -                                        int node, struct vmem_altmap *altmap)
> +static int __meminit vmemmap_populate_address(unsigned long addr, int node,
> +                                             struct vmem_altmap *altmap)
>  {
> -       unsigned long addr = start;
>         pgd_t *pgd;
>         p4d_t *p4d;
>         pud_t *pud;
>         pmd_t *pmd;
>         pte_t *pte;
>
> +       pgd = vmemmap_pgd_populate(addr, node);
> +       if (!pgd)
> +               return -ENOMEM;
> +       p4d = vmemmap_p4d_populate(pgd, addr, node);
> +       if (!p4d)
> +               return -ENOMEM;
> +       pud = vmemmap_pud_populate(p4d, addr, node);
> +       if (!pud)
> +               return -ENOMEM;
> +       pmd = vmemmap_pmd_populate(pud, addr, node);
> +       if (!pmd)
> +               return -ENOMEM;
> +       pte = vmemmap_pte_populate(pmd, addr, node, altmap);
> +       if (!pte)
> +               return -ENOMEM;
> +       vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
> +}
> +
> +int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
> +                                        int node, struct vmem_altmap *altmap)
> +{
> +       unsigned long addr = start;
> +
>         for (; addr < end; addr += PAGE_SIZE) {
> -               pgd = vmemmap_pgd_populate(addr, node);
> -               if (!pgd)
> -                       return -ENOMEM;
> -               p4d = vmemmap_p4d_populate(pgd, addr, node);
> -               if (!p4d)
> -                       return -ENOMEM;
> -               pud = vmemmap_pud_populate(p4d, addr, node);
> -               if (!pud)
> -                       return -ENOMEM;
> -               pmd = vmemmap_pmd_populate(pud, addr, node);
> -               if (!pmd)
> -                       return -ENOMEM;
> -               pte = vmemmap_pte_populate(pmd, addr, node, altmap);
> -               if (!pte)
> +               if (vmemmap_populate_address(addr, node, altmap))
>                         return -ENOMEM;
> -               vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
>         }
>
>         return 0;
> --
> 2.17.1
>