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/20230302222404.175303-1-jthoughton@google.com
Fixes: 5c041f5d1f23 ("mm: teach core mm about pte markers")
Signed-off-by: James Houghton <jthoughton@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mincore.c b/mm/mincore.c
index cd69b9db00812655c42fdc91957d6826bd97d9d6..d359650b0f75b9c099e75ecd994a0b82ac38a9fa 100644 (file)
--- a/mm/mincore.c
+++ b/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;