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[v2,46/69] mm/sparse-vmemmap: Map shared vmemmap tail pages read-only

Message ID 20260513130542.35604-47-songmuchun@bytedance.com (mailing list archive)
State Handled Elsewhere
Headers show
Series mm: Generalize HVO for HugeTLB and device DAX | expand

Commit Message

Muchun Song May 13, 2026, 1:05 p.m. UTC 
Shared vmemmap tail pages are now installed through
vmemmap_pte_populate().

Map those shared pages with PAGE_KERNEL_RO so writes to shared tail
vmemmap entries fault immediately instead of silently corrupting shared
metadata.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 mm/sparse-vmemmap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 182d0c7dd1e7..9811c92ad258 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -158,7 +158,8 @@  static pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, in
 		if (slab_is_available())
 			get_page(page);
 
-		entry = pfn_pte(page_to_pfn(page), PAGE_KERNEL);
+		/* Map shared tail page read-only to catch illegal writes. */
+		entry = pfn_pte(page_to_pfn(page), PAGE_KERNEL_RO);
 	} else {
 		void *vaddr = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);