Commit b5be83e3 authored by Gregory Fong's avatar Gregory Fong Committed by Linus Torvalds
Browse files

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
difference in alignment at reserve-time and alloc-time.

Signed-off-by: default avatarGregory Fong <>
Acked-by: default avatarMichal Nazarewicz <>
Cc: Marek Szyprowski <>
Cc: Joonsoo Kim <>
Cc: Kukjin Kim <>
Cc: Laurent Pinchart <>
Cc: Laura Abbott <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 5e19b013
......@@ -63,6 +63,17 @@ static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order)
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;
......@@ -340,7 +351,7 @@ int __init cma_declare_contiguous(phys_addr_t base,
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;
......@@ -355,13 +366,15 @@ struct page *cma_alloc(struct cma *cma, int count, unsigned int align)
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 (;;) {
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,
if (bitmap_no >= bitmap_maxno) {
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