From 6cda72047ea46272ecb9cc71acf1231cea07167a Mon Sep 17 00:00:00 2001 From: Wei Yang Date: Thu, 6 Aug 2020 23:23:59 -0700 Subject: [PATCH] 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 Signed-off-by: Andrew Morton Acked-by: David Hildenbrand Link: http://lkml.kernel.org/r/20200703031828.14645-1-richard.weiyang@linux.alibaba.com Signed-off-by: Linus Torvalds --- mm/sparse-vmemmap.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index 41eeac67723b..16183d85a7d5 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -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;