The patch titled
Subject: mm: cma: align to physical address, not CMA region position
has been added to the -mm tree. Its filename is
mm-cma-align-to-physical-address-not-cma-region-position.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-cma-align-to-physical-address-not-cma-region-position.patch
echo and later at
echo http://ozlabs.org/~akpm/mmotm/broken-out/mm-cma-align-to-physical-address-not-cma-region-position.patch
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From: Gregory Fong <gregory.0xf0@xxxxxxxxx>
Subject: mm: cma: align to physical address, not CMA region position
The alignment in cma_alloc() was done w.r.t. the bitmap. This is a
problem when, for example:
- a device requires 16M (order 12) alignment
- the CMA region is not 16 M aligned
In such a case, can result with the CMA region starting at, say,
0x2f800000 but any allocation you make from there will be aligned from
there. Requesting an allocation of 32 M with 16 M alignment will result
in an allocation from 0x2f800000 to 0x31800000, which doesn't work very
well if your strange device requires 16M alignment.
Change to use bitmap_find_next_zero_area_off() to account for the
Signed-off-by: Gregory Fong <gregory.0xf0@xxxxxxxxx>
Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Kukjin Kim <kgene.kim@xxxxxxxxxxx>
Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Cc: Laura Abbott <lauraa@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/cma.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff -puN mm/cma.c~mm-cma-align-to-physical-address-not-cma-region-position mm/cma.c
--- a/mm/cma.c~mm-cma-align-to-physical-address-not-cma-region-position
+++ a/mm/cma.c
@@ -63,6 +63,17 @@ static unsigned long cma_bitmap_aligned_
return (1UL << (align_order - cma->order_per_bit)) - 1;
}
+static unsigned long cma_bitmap_aligned_offset(struct cma *cma, int align_order)
+{
+ unsigned int alignment;
+
+ if (align_order <= cma->order_per_bit)
+ return 0;
+ alignment = 1UL << (align_order - cma->order_per_bit);
+ return ALIGN(cma->base_pfn, alignment) -
+ (cma->base_pfn >> cma->order_per_bit);
+}
+
static unsigned long cma_bitmap_maxno(struct cma *cma)
{
return cma->count >> cma->order_per_bit;
@@ -328,7 +339,7 @@ err:
*/
struct page *cma_alloc(struct cma *cma, int count, unsigned int align)
{
- unsigned long mask, pfn, start = 0;
+ unsigned long mask, offset, pfn, start = 0;
unsigned long bitmap_maxno, bitmap_no, bitmap_count;
struct page *page = NULL;
int ret;
@@ -343,13 +354,15 @@ struct page *cma_alloc(struct cma *cma,
return NULL;
mask = cma_bitmap_aligned_mask(cma, align);
+ offset = cma_bitmap_aligned_offset(cma, align);
bitmap_maxno = cma_bitmap_maxno(cma);
bitmap_count = cma_bitmap_pages_to_bits(cma, count);
for (;;) {
mutex_lock(&cma->lock);
- bitmap_no = bitmap_find_next_zero_area(cma->bitmap,
- bitmap_maxno, start, bitmap_count, mask);
+ bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
+ bitmap_maxno, start, bitmap_count, mask,
+ offset);
if (bitmap_no >= bitmap_maxno) {
mutex_unlock(&cma->lock);
break;
_
Patches currently in -mm which might be from gregory.0xf0@xxxxxxxxx are
lib-bitmap-added-alignment-offset-for-bitmap_find_next_zero_area.patch
mm-cma-align-to-physical-address-not-cma-region-position.patch
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