powerpc/mm/hugetlb: Sanity check gigantic hugepage count

Limit the number of gigantic hugepages specified by the
hugepages= parameter to MAX_NUMBER_GPAGES.

Signed-off-by: James Yang <James.Yang@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index af56de8..747e0c6 100644 (file)
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -355,6 +355,13 @@ static int __init do_gpage_early_setup(char *param, char *val,
                if (size != 0) {
                        if (sscanf(val, "%lu", &npages) <= 0)
                                npages = 0;
+                       if (npages > MAX_NUMBER_GPAGES) {
+                               pr_warn("MMU: %lu pages requested for page "
+                                       "size %llu KB, limiting to "
+                                       __stringify(MAX_NUMBER_GPAGES) "\n",
+                                       npages, size / 1024);
+                               npages = MAX_NUMBER_GPAGES;
+                       }
                        gpage_npages[shift_to_mmu_psize(__ffs(size))] = npages;
                        size = 0;
                }