Hi, Will, On Fri, Jul 22, 2022 at 5:16 PM Will Deacon <will@xxxxxxxxxx> wrote: > > On Thu, Jul 21, 2022 at 09:04:18PM +0800, Huacai Chen wrote: > > diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c > > index 0abcb0a5f1b5..eafd084b8e19 100644 > > --- a/mm/sparse-vmemmap.c > > +++ b/mm/sparse-vmemmap.c > > @@ -694,6 +694,69 @@ int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end, > > return vmemmap_populate_range(start, end, node, altmap, NULL); > > } > > > > +void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node, > > + unsigned long addr, unsigned long next) > > +{ > > +} > > + > > +int __weak __meminit vmemmap_check_pmd(pmd_t *pmd, int node, unsigned long addr, > > + unsigned long next) > > +{ > > + return 0; > > +} > > + > > +int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end, > > + int node, struct vmem_altmap *altmap) > > +{ > > + unsigned long addr; > > + unsigned long next; > > + pgd_t *pgd; > > + p4d_t *p4d; > > + pud_t *pud; > > + pmd_t *pmd; > > + > > + for (addr = start; addr < end; addr = next) { > > + next = pmd_addr_end(addr, end); > > + > > + 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 = pmd_offset(pud, addr); > > + if (pmd_none(READ_ONCE(*pmd))) { > > + void *p; > > + > > + p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap); > > + if (p) { > > + vmemmap_set_pmd(pmd, p, node, addr, next); > > + continue; > > + } else if (altmap) { > > + /* > > + * No fallback: In any case we care about, the > > + * altmap should be reasonably sized and aligned > > + * such that vmemmap_alloc_block_buf() will always > > + * succeed. If there is no more space in the altmap > > + * and we'd have to fallback to PTE (highly unlikely). > > Can you tweak the last couple of sentences please, as they don't make sense > to me? To be specific, I'd suggest replacing: > > "If there is no more space in the altmap and we'd have to fallback to PTE > (highly unlikely). That could indicate an altmap-size configuration > issue." > > with something like: > > "For consistency with the PTE case, return an error here as failure could > indicate a configuration issue with the size of the altmap." > > With that: > > Acked-by: Will Deacon <will@xxxxxxxxxx> OK, I will send V5, thanks. Huacai > > Will