From 6ad28e7e52e2bae76b1d3eb4466999d04d50db92 Mon Sep 17 00:00:00 2001 From: David Hildenbrand <david@redhat.com> Date: Wed, 22 May 2024 14:57:13 +0200 Subject: [PATCH] mm/rmap: sanity check that zeropages are not passed to RMAP Using insert_page() we might have previously ended up passing the zeropage into rmap code. Make sure that won't happen again. Note that we won't check the huge zeropage for now, which might still end up in RMAP code. Link: https://lkml.kernel.org/r/20240522125713.775114-4-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Vincent Donnefort <vdonnefort@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- include/linux/rmap.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 7229b9baf20d8..5cb0d419a1d75 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -200,6 +200,9 @@ static inline void __folio_rmap_sanity_checks(struct folio *folio, /* hugetlb folios are handled separately. */ VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio); + /* When (un)mapping zeropages, we should never touch ref+mapcount. */ + VM_WARN_ON_FOLIO(is_zero_folio(folio), folio); + /* * TODO: we get driver-allocated folios that have nothing to do with * the rmap using vm_insert_page(); therefore, we cannot assume that -- GitLab