Dan Williams <dan.j.williams@xxxxxxxxx> writes:
> Allow sub-section sized ranges to be added to the memmap.
> populate_section_memmap() takes an explict pfn range rather than
> assuming a full section, and those parameters are plumbed all the way
> through to vmmemap_populate(). There should be no sub-section usage in
> current deployments. New warnings are added to clarify which memmap
> allocation paths are sub-section capable.
>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> Cc: Oscar Salvador <osalvador@xxxxxxx>
> Reviewed-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> arch/x86/mm/init_64.c | 4 ++-
> include/linux/mm.h | 4 ++-
> mm/sparse-vmemmap.c | 21 +++++++++++------
> mm/sparse.c | 61 +++++++++++++++++++++++++++++++------------------
> 4 files changed, 57 insertions(+), 33 deletions(-)
>
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 8335ac6e1112..688fb0687e55 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -1520,7 +1520,9 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
> {
> int err;
>
> - if (boot_cpu_has(X86_FEATURE_PSE))
> + if (end - start < PAGES_PER_SECTION * sizeof(struct page))
> + err = vmemmap_populate_basepages(start, end, node);
> + else if (boot_cpu_has(X86_FEATURE_PSE))
> err = vmemmap_populate_hugepages(start, end, node, altmap);
> else if (altmap) {
> pr_err_once("%s: no cpu support for altmap allocations\n",
Can we move this to another patch? I am wondering what the x86 behaviour
here is? If the range is less that PAGES_PER_SECTION we don't allow to
use pmem as the map device? We sliently use memory range?
-aneesh
