powerpc: Don't use a 16G page if beyond mem= limits

If mem= is used on the boot command line to limit memory then the memory block where a 16G page resides may not be available.

Thanks to Michael Ellerman for finding the problem.

Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 5c64af17475..8d5b4758c13 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -382,8 +382,10 @@ 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);
-        lmb_reserve(phys_addr, block_size * expected_pages);
-        add_gpage(phys_addr, block_size, expected_pages);
+        if (phys_addr + (16 * GB) <= lmb_end_of_DRAM()) {
+                lmb_reserve(phys_addr, block_size * expected_pages);
+                add_gpage(phys_addr, block_size, expected_pages);
+        }
         return 0;
 }
 #endif /* CONFIG_HUGETLB_PAGE */