From 7549d07b1e3749927bdcbef5dc4ccfe6e0d63bb2 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Thu, 2 Jul 2020 10:19:30 +0100 Subject: [PATCH] mm: Preserve the PG_arch_2 flag in __split_huge_page_tail() When a huge page is split into normal pages, part of the head page flags are transferred to the tail pages. However, the PG_arch_* flags are not part of the preserved set. PG_arch_2 is used by the arm64 MTE support to mark pages that have valid tags. The absence of such flag would cause the arm64 set_pte_at() to clear the tags in order to avoid stale tags exposed to user or the swapping out hooks to ignore the tags. Not preserving PG_arch_2 on huge page splitting leads to tag corruption in the tail pages. Preserve the newly added PG_arch_2 flag in __split_huge_page_tail(). Signed-off-by: Catalin Marinas Cc: Andrew Morton --- mm/huge_memory.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 2ccff8472cd4b..1a5773c95f533 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2337,6 +2337,9 @@ static void __split_huge_page_tail(struct page *head, int tail, (1L << PG_workingset) | (1L << PG_locked) | (1L << PG_unevictable) | +#ifdef CONFIG_64BIT + (1L << PG_arch_2) | +#endif (1L << PG_dirty))); /* ->mapping in first tail page is compound_mapcount */ -- 2.39.5