The patch titled
Subject: mm/rmap: sanity check that zeropages are not passed to RMAP
has been added to the -mm mm-unstable branch. Its filename is
mm-rmap-sanity-check-that-zeropages-are-not-passed-to-rmap.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-rmap-sanity-check-that-zeropages-are-not-passed-to-rmap.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: sanity check that zeropages are not passed to RMAP
Date: Wed, 22 May 2024 14:57:13 +0200
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@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Vincent Donnefort <vdonnefort@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/rmap.h | 3 +++
1 file changed, 3 insertions(+)
--- a/include/linux/rmap.h~mm-rmap-sanity-check-that-zeropages-are-not-passed-to-rmap
+++ a/include/linux/rmap.h
@@ -200,6 +200,9 @@ static inline void __folio_rmap_sanity_c
/* 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
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-memory-move-page_count-check-into-validate_page_before_insert.patch
mm-memory-cleanly-support-zeropage-in-vm_insert_page-vm_map_pages-and-vmf_insert_mixed.patch
mm-rmap-sanity-check-that-zeropages-are-not-passed-to-rmap.patch
