This is a note to let you know that I've just added the patch titled
mm/hugetlb: separate path for hwpoison entry in copy_hugetlb_page_range()
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-hugetlb-separate-path-for-hwpoison-entry-in-copy_hugetlb_page_range.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c2cb0dcce9dd8b748b6ca8bb8d4a389f2e232307 Mon Sep 17 00:00:00 2001
From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Date: Mon, 4 Jul 2022 10:33:05 +0900
Subject: mm/hugetlb: separate path for hwpoison entry in copy_hugetlb_page_range()
From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
commit c2cb0dcce9dd8b748b6ca8bb8d4a389f2e232307 upstream.
Originally copy_hugetlb_page_range() handles migration entries and
hwpoisoned entries in similar manner. But recently the related code path
has more code for migration entries, and when
is_writable_migration_entry() was converted to
!is_readable_migration_entry(), hwpoison entries on source processes got
to be unexpectedly updated (which is legitimate for migration entries, but
not for hwpoison entries). This results in unexpected serious issues like
kernel panic when forking processes with hwpoison entries in pmd.
Separate the if branch into one for hwpoison entries and one for migration
entries.
Link: https://lkml.kernel.org/r/20220704013312.2415700-3-naoya.horiguchi@xxxxxxxxx
Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive")
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Reviewed-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [5.18]
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Liu Shixin <liushixin2@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4764,8 +4764,13 @@ again:
* sharing with another vma.
*/
;
- } else if (unlikely(is_hugetlb_entry_migration(entry) ||
- is_hugetlb_entry_hwpoisoned(entry))) {
+ } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) {
+ bool uffd_wp = huge_pte_uffd_wp(entry);
+
+ if (!userfaultfd_wp(dst_vma) && uffd_wp)
+ entry = huge_pte_clear_uffd_wp(entry);
+ set_huge_pte_at(dst, addr, dst_pte, entry);
+ } else if (unlikely(is_hugetlb_entry_migration(entry))) {
swp_entry_t swp_entry = pte_to_swp_entry(entry);
if (is_writable_migration_entry(swp_entry) && cow) {
Patches currently in stable-queue which might be from naoya.horiguchi@xxxxxxx are
queue-5.18/mm-hugetlb-separate-path-for-hwpoison-entry-in-copy_hugetlb_page_range.patch
