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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: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Hildenbrand <david@redhat.com>
Link: http://lkml.kernel.org/r/20200703031828.14645-1-richard.weiyang@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Wei Yang 2020-08-06 23:23:59 -07:00 committed by Linus Torvalds
parent ef69bc9f68
commit 6cda72047e
1 changed files with 5 additions and 13 deletions
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18
mm/sparse-vmemmap.c
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@ -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;