The patch titled
Subject: mm-rmap-simplify-pageanonexclusive-sanity-checks-when-adding-anon-rmap-fix
has been added to the -mm mm-unstable branch. Its filename is
mm-rmap-simplify-pageanonexclusive-sanity-checks-when-adding-anon-rmap-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-rmap-simplify-pageanonexclusive-sanity-checks-when-adding-anon-rmap-fix.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm-rmap-simplify-pageanonexclusive-sanity-checks-when-adding-anon-rmap-fix
Date: Mon, 18 Sep 2023 11:16:57 +0200
While PTE-mapping a THP, we temporarily have an exclusive page of a THP
mapped by both, a PMD and a PTE at the same time. Update our check to
allow for that combination.
Link: https://lkml.kernel.org/r/d8e5a093-2e22-c14b-7e64-6da280398d9f@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reported-by: syzbot+6e4f59235036c3c2e296@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/rmap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/mm/rmap.c~mm-rmap-simplify-pageanonexclusive-sanity-checks-when-adding-anon-rmap-fix
+++ a/mm/rmap.c
@@ -1249,8 +1249,10 @@ void page_add_anon_rmap(struct page *pag
}
if (flags & RMAP_EXCLUSIVE)
SetPageAnonExclusive(page);
- VM_WARN_ON_FOLIO(page_mapcount(page) > 1 && PageAnonExclusive(page),
- folio);
+ /* While PTE-mapping a THP we have a PMD and a PTE mapping. */
+ VM_WARN_ON_FOLIO((atomic_read(&page->_mapcount) > 0 ||
+ (folio_test_large(folio) && folio_entire_mapcount(folio) > 1)) &&
+ PageAnonExclusive(page), folio);
mlock_vma_folio(folio, vma, compound);
}
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-rmap-drop-stale-comment-in-page_add_anon_rmap-and-hugepage_add_anon_rmap.patch
mm-rmap-move-setpageanonexclusive-out-of-__page_set_anon_rmap.patch
mm-rmap-move-folio_test_anon-check-out-of-__folio_set_anon.patch
mm-rmap-warn-on-new-pte-mapped-folios-in-page_add_anon_rmap.patch
mm-rmap-simplify-pageanonexclusive-sanity-checks-when-adding-anon-rmap.patch
mm-rmap-simplify-pageanonexclusive-sanity-checks-when-adding-anon-rmap-fix.patch
mm-rmap-pass-folio-to-hugepage_add_anon_rmap.patch
