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>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index af56de82375d..747e0c616526 100644
--- 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;
                 }