From 5b47348fc0b18a78c96f8474cc90b7525ad1bbfe Mon Sep 17 00:00:00 2001 From: Liu Shixin Date: Thu, 17 Nov 2022 15:56:01 +0800 Subject: [PATCH] arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud The page table check trigger BUG_ON() unexpectedly when collapse hugepage: ------------[ cut here ]------------ kernel BUG at mm/page_table_check.c:82! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750 Hardware name: linux,dummy-virt (DT) pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : page_table_check_clear.isra.0+0x258/0x3f0 lr : page_table_check_clear.isra.0+0x240/0x3f0 [...] Call trace: page_table_check_clear.isra.0+0x258/0x3f0 __page_table_check_pmd_clear+0xbc/0x108 pmdp_collapse_flush+0xb0/0x160 collapse_huge_page+0xa08/0x1080 hpage_collapse_scan_pmd+0xf30/0x1590 khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8 khugepaged+0x338/0x518 kthread+0x278/0x2f8 ret_from_fork+0x10/0x20 [...] Since pmd_user_accessible_page() doesn't check if a pmd is leaf, it decrease file_map_count for a non-leaf pmd comes from collapse_huge_page(). and so trigger BUG_ON() unexpectedly. Fix this problem by using pmd_leaf() insteal of pmd_present() in pmd_user_accessible_page(). Moreover, use pud_leaf() for pud_user_accessible_page() too. Fixes: 42b2547137f5 ("arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK") Reported-by: Denys Vlasenko Signed-off-by: Liu Shixin Reviewed-by: David Hildenbrand Acked-by: Pasha Tatashin Reviewed-by: Kefeng Wang Acked-by: Will Deacon Link: https://lore.kernel.org/r/20221117075602.2904324-2-liushixin2@huawei.com Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/pgtable.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 71a1af42f0e8..edf6625ce965 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -863,12 +863,12 @@ static inline bool pte_user_accessible_page(pte_t pte) static inline bool pmd_user_accessible_page(pmd_t pmd) { - return pmd_present(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd)); + return pmd_leaf(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd)); } static inline bool pud_user_accessible_page(pud_t pud) { - return pud_present(pud) && pud_user(pud); + return pud_leaf(pud) && pud_user(pud); } #endif -- GitLab