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.

Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug")
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Baoquan He <bhe@redhat.com>
Link: http://lkml.kernel.org/r/20200210005048.10437-1-richardw.yang@linux.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/sparse.c b/mm/sparse.c
index 65599e8bd6365665f5d74f6627a4996697afc8ea..55fe305e8d7ba7e68e7a14487c1cc4a377b82132 100644 (file)
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -894,7 +894,7 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn,
 
        /* 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;