On 31/01/2017 5:11 PM, Michael Ellerman wrote:
Rui Teng <rui.t...@linux.vnet.ibm.com> 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?

Yes, I found this problem only by code inspection. We were finding the
ways to enable 16G huge page besides changing the device tree. For example, provide a new interface to set these size and pages parameters.
So that I think it may cause problem here.


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


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