From 89f43e1ce6f60d4f44399059595ac47f7a90a393 Mon Sep 17 00:00:00 2001 From: Zhenhua Huang Date: Fri, 21 Mar 2025 15:00:19 +0800 Subject: [PATCH] arm64: mm: Correct the update of max_pfn Hotplugged memory can be smaller than the original memory. For example, on my target: root@genericarmv8:~# cat /sys/kernel/debug/memblock/memory 0: 0x0000000064005000..0x0000000064023fff 0 NOMAP 1: 0x0000000064400000..0x00000000647fffff 0 NOMAP 2: 0x0000000068000000..0x000000006fffffff 0 DRV_MNG 3: 0x0000000088800000..0x0000000094ffefff 0 NONE 4: 0x0000000094fff000..0x0000000094ffffff 0 NOMAP max_pfn will affect read_page_owner. Therefore, it should first compare and then select the larger value for max_pfn. Fixes: 8fac67ca236b ("arm64: mm: update max_pfn after memory hotplug") Cc: # 6.1.x Signed-off-by: Zhenhua Huang Acked-by: David Hildenbrand Reviewed-by: Anshuman Khandual Link: https://lore.kernel.org/r/20250321070019.1271859-1-quic_zhenhuah@quicinc.com Signed-off-by: Catalin Marinas --- arch/arm64/mm/mmu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 3c54dea1303ff..eaaa9b36202b5 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1358,7 +1358,8 @@ int arch_add_memory(int nid, u64 start, u64 size, __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size); else { - max_pfn = PFN_UP(start + size); + /* Address of hotplugged memory can be smaller */ + max_pfn = max(max_pfn, PFN_UP(start + size)); max_low_pfn = max_pfn; } -- 2.39.5