Re: [PATCH] powerpc/mm: fix a hardcode on memory boundary checking

From: Michael Ellerman
Date: Tue Jan 31 2017 - 04:12:03 EST


Rui Teng <rui.teng@xxxxxxxxxxxxxxxxxx> writes:

> The offset of hugepage block will not be 16G, if the expected
> page is more than one. Calculate the totol size instead of the
> hardcode value.

I assume you found this by code inspection and not by triggering an
actual bug?

cheers

> diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
> index 8033493..b829f8e 100644
> --- a/arch/powerpc/mm/hash_utils_64.c
> +++ b/arch/powerpc/mm/hash_utils_64.c
> @@ -506,7 +506,7 @@ static int __init htab_dt_scan_hugepage_blocks(unsigned long node,
> printk(KERN_INFO "Huge page(16GB) memory: "
> "addr = 0x%lX size = 0x%lX pages = %d\n",
> phys_addr, block_size, expected_pages);
> - if (phys_addr + (16 * GB) <= memblock_end_of_DRAM()) {
> + if (phys_addr + block_size * expected_pages <= memblock_end_of_DRAM()) {
> memblock_reserve(phys_addr, block_size * expected_pages);
> add_gpage(phys_addr, block_size, expected_pages);
> }
> --
> 2.9.0