Commit 6cda7204 authored by Wei Yang's avatar Wei Yang Committed by Linus Torvalds
Browse files

mm/sparse: only sub-section aligned range would be populated 



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: default avatarWei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Link: http://lkml.kernel.org/r/20200703031828.14645-1-richard.weiyang@linux.alibaba.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ef69bc9f

mm/sparse-vmemmap.c

+6 −14
Original line number Diff line number Diff line
@@ -251,20 +251,12 @@ int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end, 
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;

	unsigned long start = (unsigned long) pfn_to_page(pfn);

	unsigned long end = start + nr_pages * sizeof(struct page);



	/*

	 * 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);

	if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||

		!IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))

		return NULL;



	if (vmemmap_populate(start, end, nid, altmap))

		return NULL;