Re: [PATCH 2/4] RISC-V: Set maximum number of mapped pages correctly

From: Palmer Dabbelt
Date: Sat Jul 25 2020 - 01:12:50 EST

On Wed, 15 Jul 2020 16:30:07 PDT (-0700), Atish Patra wrote:
Currently, maximum number of mapper pages are set to the pfn calculated
from the memblock size of the memblock containing kernel. This will work
until that memblock spans the entire memory. However, it will be set to
a wrong value if there are multiple memblocks defined in kernel
(e.g. with efi runtime services).

Set the the maximum value to the pfn calculated from dram size.

Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
arch/riscv/mm/init.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index f4adb3684f3d..8d22973bde40 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -150,9 +150,9 @@ void __init setup_bootmem(void)
/* Reserve from the start of the kernel to the end of the kernel */
memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);

- set_max_mapnr(PFN_DOWN(mem_size));
max_pfn = PFN_DOWN(memblock_end_of_DRAM());
max_low_pfn = max_pfn;
+ set_max_mapnr(max_low_pfn);


This one I'm putting on fixes, as there's nothing preventing us from having
multiple memory regions in a current boot and this seems very safe.