On 03.07.20 05:18, Wei Yang wrote:
> There are two code path which invoke __populate_section_memmap()
>
> * sparse_init_nid()
> * sparse_add_section()
>
> For both case, we are sure the memory range is sub-section aligned.
>
> * we pass PAGES_PER_SECTION to sparse_init_nid()
> * we check range by check_pfn_span() before calling
> sparse_add_section()
>
> Also, the counterpart of __populate_section_memmap(), we don't do such
> calculation and check since the range is checked by check_pfn_span() in
> __remove_pages().
>
> Clear the calculation and check to keep it simple and comply with its
> counterpart.
>
> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
>
> ---
> v2:
> * add a warn on once for unaligned range, suggested by David
> ---
> mm/sparse-vmemmap.c | 20 ++++++--------------
> 1 file changed, 6 insertions(+), 14 deletions(-)
>
> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
> index 0db7738d76e9..8d3a1b6287c5 100644
> --- a/mm/sparse-vmemmap.c
> +++ b/mm/sparse-vmemmap.c
> @@ -247,20 +247,12 @@ int __meminit vmemmap_populate_basepages(unsigned long start,
> struct page * __meminit __populate_section_memmap(unsigned long pfn,
> unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
> {
> - unsigned long start;
> - unsigned long end;
> -
> - /*
> - * The minimum granularity of memmap extensions is
> - * PAGES_PER_SUBSECTION as allocations are tracked in the
> - * 'subsection_map' bitmap of the section.
> - */
> - end = ALIGN(pfn + nr_pages, PAGES_PER_SUBSECTION);
> - pfn &= PAGE_SUBSECTION_MASK;
> - nr_pages = end - pfn;
> -
> - start = (unsigned long) pfn_to_page(pfn);
> - end = start + nr_pages * sizeof(struct page);
> + unsigned long start = (unsigned long) pfn_to_page(pfn);
> + unsigned long end = start + nr_pages * sizeof(struct page);
> +
> + if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
> + !IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
> + return NULL;
Nit: indentation of both IS_ALIGNED should match.
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
>
> if (vmemmap_populate(start, end, nid, altmap))
> return NULL;
>
--
Thanks,
David / dhildenb
