mm: teach mincore_hugetlb about pte markers

By checking huge_pte_none(), we incorrectly classify PTE markers as
"present".  Instead, check huge_pte_none_mostly(), classifying PTE markers
the same as if the PTE were completely blank.

PTE markers, unlike other kinds of swap entries, don't reference any
physical page and don't indicate that a physical page was mapped
previously.  As such, treat them as non-present for the sake of mincore().

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 5c041f5 ("mm: teach core mm about pte markers")
Signed-off-by: James Houghton <[email protected]>
Acked-by: Peter Xu <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: James Houghton <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: 48ca

mm/mincore.c

@@ -33,7 +33,7 @@ static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
 	 * Hugepages under user process are always in RAM and never
 	 * swapped out, but theoretically it needs to be checked.
 	 */
-	present = pte && !huge_pte_none(huge_ptep_get(pte));
+	present = pte && !huge_pte_none_mostly(huge_ptep_get(pte));
 	for (; addr != end; vec++, addr += PAGE_SIZE)
 		*vec = present;
 	walk->private = vec;