The quilt patch titled
Subject: mm/gup: add missing gup_must_unshare() check to gup_huge_pgd()
has been removed from the -mm tree. Its filename was
mm-gup-add-missing-gup_must_unshare-check-to-gup_huge_pgd.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Subject: mm/gup: add missing gup_must_unshare() check to gup_huge_pgd()
Date: Sat, 6 May 2023 15:05:25 +0100
All other instances of gup_huge_pXd() perform the unshare check, so update
the PGD-specific function to do so as well.
While checking pgd_write() might seem unusual, this function already
performs such a check via pgd_access_permitted() so this is in line with
the existing implementation.
David said:
: This change makes unshare handling across all GUP-fast variants
: consistent, which is desirable as GUP-fast is complicated enough
: already even when consistent.
:
: This function was the only one I seemed to have missed (or left out and
: forgot why -- maybe because it's really dead code for now). The COW
: selftest would identify the problem, so far there was no report.
: Either the selftest wasn't run on corresponding architectures with that
: hugetlb size, or that code is still dead code and unused by
: architectures.
:
: the original commit(s) that added unsharing explain why we care about
: these checks:
:
: a7f226604170acd6 ("mm/gup: trigger FAULT_FLAG_UNSHARE when R/O-pinning a possibly shared anonymous page")
: 84209e87c6963f92 ("mm/gup: reliable R/O long-term pinning in COW mappings")
Link: https://lkml.kernel.org/r/cb971ac8dd315df97058ea69442ecc007b9a364a.1683381545.git.lstoakes@xxxxxxxxx
Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/mm/gup.c~mm-gup-add-missing-gup_must_unshare-check-to-gup_huge_pgd
+++ a/mm/gup.c
@@ -2755,6 +2755,11 @@ static int gup_huge_pgd(pgd_t orig, pgd_
return 0;
}
+ if (!pgd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
+ gup_put_folio(folio, refs, flags);
+ return 0;
+ }
+
*nr += refs;
folio_set_referenced(folio);
return 1;
_
Patches currently in -mm which might be from lstoakes@xxxxxxxxx are
mm-vmalloc-do-not-output-a-spurious-warning-when-huge-vmalloc-fails.patch
