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

Dan Williams
2021-05-05T22:43:43Z

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