From 68faed630fc151a7a1c4853df00fb3dcacf782b4 Mon Sep 17 00:00:00 2001 From: Weijie Yang Date: Mon, 13 Oct 2014 15:51:03 -0700 Subject: mm/cma: fix cma bitmap aligned mask computing The current cma bitmap aligned mask computation is incorrect. It could cause an unexpected alignment when using cma_alloc() if the wanted align order is larger than cma->order_per_bit. Take kvm for example (PAGE_SHIFT = 12), kvm_cma->order_per_bit is set to 6. When kvm_alloc_rma() tries to alloc kvm_rma_pages, it will use 15 as the expected align value. After using the current implementation however, we get 0 as cma bitmap aligned mask other than 511. This patch fixes the cma bitmap aligned mask calculation. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Weijie Yang Acked-by: Michal Nazarewicz Cc: Joonsoo Kim Cc: "Aneesh Kumar K.V" Cc: [3.17] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/cma.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/cma.c b/mm/cma.c index 474c644a0dc6..a951a3b3ed36 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -58,7 +58,9 @@ unsigned long cma_get_size(struct cma *cma) static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order) { - return (1UL << (align_order >> cma->order_per_bit)) - 1; + if (align_order <= cma->order_per_bit) + return 0; + return (1UL << (align_order - cma->order_per_bit)) - 1; } static unsigned long cma_bitmap_maxno(struct cma *cma) -- cgit v1.2.3-59-g8ed1b