On Wed, Jun 18, 2014 at 01:48:15PM -0700, Andrew Morton wrote:

On Mon, 16 Jun 2014 14:40:46 +0900 Joonsoo Kim [off-list ref] wrote:

quoted

PPC KVM's CMA area management requires arbitrary bitmap granularity,
since they want to reserve very large memory and manage this region
with bitmap that one bit for several pages to reduce management overheads.
So support arbitrary bitmap granularity for following generalization.

...

--- a/drivers/base/dma-contiguous.c
+++ b/drivers/base/dma-contiguous.c

@@ -38,6 +38,7 @@ struct cma {
 	unsigned long	base_pfn;
 	unsigned long	count;
 	unsigned long	*bitmap;
+	unsigned int order_per_bit; /* Order of pages represented by one bit */
 	struct mutex	lock;
 };
 

@@ -157,9 +158,37 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
 
 static DEFINE_MUTEX(cma_mutex);
 
+static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order)
+{
+	return (1 << (align_order >> cma->order_per_bit)) - 1;
+}

Might want a "1UL << ..." here.

Okay!

quoted

+static unsigned long cma_bitmap_maxno(struct cma *cma)
+{
+	return cma->count >> cma->order_per_bit;
+}
+
+static unsigned long cma_bitmap_pages_to_bits(struct cma *cma,
+						unsigned long pages)
+{
+	return ALIGN(pages, 1 << cma->order_per_bit) >> cma->order_per_bit;
+}

Ditto.  I'm not really sure what the compiler will do in these cases,
but would prefer not to rely on it anyway!

Okay!

Thanks for fix!