Re: [PATCH v3 06/14] mm/sparse-vmemmap: refactor core of vmemmap_populate_basepages() to helper

On 7/28/21 7:04 AM, Dan Williams wrote:

On Wed, Jul 14, 2021 at 12:36 PM Joao Martins [off-list ref] wrote:

quoted

In preparation for describing a memmap with compound pages, 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.

Signed-off-by: Joao Martins <redacted>
---
 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 80d3ba30d345..76f4158f6301 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c

@@ -570,33 +570,41 @@ 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);

Missing a return here:

mm/sparse-vmemmap.c:598:1: error: control reaches end of non-void
function [-Werror=return-type]

Yes, it's fixed up in a later patch 

That fixup definitely needs to be moved here.

, but might as well not leave the
bisect breakage lying around, and the kbuild robot would gripe about
this eventually as well.

Yeap. Fixed, thanks for noticing.

quoted

+}
+
+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;

I'd prefer:

rc = vmemmap_populate_address(addr, node, altmap);
if (rc)
    return rc;

...in case future refactoring adds different error codes to pass up.

Fixed.