From: Weijie Yang <weijie.yang@xxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxx: coding-style fixes]
Signed-off-by: Weijie Yang <weijie.yang@xxxxxxxxxxx>
Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [3.17]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/cma.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff -puN mm/cma.c~mm-cma-fix-cma-bitmap-aligned-mask-computing mm/cma.c
--- a/mm/cma.c~mm-cma-fix-cma-bitmap-aligned-mask-computing
+++ a/mm/cma.c
@@ -58,7 +58,9 @@ unsigned long cma_get_size(struct cma *c
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)
_
--
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