From: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx> Subject: mm/sparsemem: get address to page struct instead of address to pfn memmap should be the address to page struct instead of address to pfn. As mentioned by David, if system memory and devmem sit within a section, the mismatch address would lead kdump to dump unexpected memory. Since sub-section only works for SPARSEMEM_VMEMMAP, pfn_to_page() is valid to get the page struct address at this point. Link: http://lkml.kernel.org/r/20200210005048.10437-1-richardw.yang@xxxxxxxxxxxxxxx Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx> Acked-by: David Hildenbrand <david@xxxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Baoquan He <bhe@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/sparse.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/sparse.c~mm-sparsemem-get-address-to-page-struct-instead-of-address-to-pfn +++ a/mm/sparse.c @@ -894,7 +894,7 @@ int __meminit sparse_add_section(int nid /* Align memmap to section boundary in the subsection case */ if (section_nr_to_pfn(section_nr) != start_pfn) - memmap = pfn_to_kaddr(section_nr_to_pfn(section_nr)); + memmap = pfn_to_page(section_nr_to_pfn(section_nr)); sparse_init_one_section(ms, section_nr, memmap, ms->usage, 0); return 0; _
