+ mm-teach-mincore_hugetlb-about-pte-markers.patch added to mm-hotfixes-unstable branch

+ mm-teach-mincore_hugetlb-about-pte-markers.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: teach mincore_hugetlb about pte markers
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-teach-mincore_hugetlb-about-pte-markers.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-teach-mincore_hugetlb-about-pte-markers.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: James Houghton <jthoughton@google.com>
Subject: mm: teach mincore_hugetlb about pte markers
Date: Thu, 2 Mar 2023 22:24:04 +0000

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>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---


--- a/mm/mincore.c~mm-teach-mincore_hugetlb-about-pte-markers
+++ a/mm/mincore.c
@@ -33,7 +33,7 @@ static int mincore_hugetlb(pte_t *pte, u
 	 * 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;
_

Patches currently in -mm which might be from jthoughton@google.com are

mm-teach-mincore_hugetlb-about-pte-markers.patch