From 909ba297beb50981a9d12364688d3c5f3084c6eb Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 20 Jan 2015 04:38:25 +0100 Subject: [PATCH] ARM: 8292/1: mm: fix size rounding-down of arm_add_memory() function The current rounding of "size" is wrong: - If "start" is sufficiently near the next page boundary, "size" is decremented by more than enough and the last page is lost. - If "size" is sufficiently small, it is wrapped around and gets a bogus value. Signed-off-by: Masahiro Yamada Acked-by: Geert Uytterhoeven Acked-by: Ard Biesheuvel Signed-off-by: Russell King --- arch/arm/kernel/setup.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index f9c863911038..d13f185e7bd5 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -657,10 +657,13 @@ int __init arm_add_memory(u64 start, u64 size) /* * Ensure that start/size are aligned to a page boundary. - * Size is appropriately rounded down, start is rounded up. + * Size is rounded down, start is rounded up. */ - size -= start & ~PAGE_MASK; aligned_start = PAGE_ALIGN(start); + if (aligned_start > start + size) + size = 0; + else + size -= aligned_start - start; #ifndef CONFIG_ARCH_PHYS_ADDR_T_64BIT if (aligned_start > ULONG_MAX) {