From c94249271aaff37aeb0324ac4cfd1fcb53d25a8d Mon Sep 17 00:00:00 2001 From: Weijie Yang Date: Mon, 13 Oct 2014 15:51:03 -0700 Subject: [PATCH] mm/cma: fix cma bitmap aligned mask computing commit 68faed630fc151a7a1c4853df00fb3dcacf782b4 upstream. 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" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/cma.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/cma.c b/mm/cma.c index c17751c0dcafb..0ab564623ea84 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -57,7 +57,9 @@ 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) -- 2.47.2