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. Cc: Michal Nazarewicz <[email protected]> Signed-off-by: Gregory Fong <[email protected]> --- mm/cma.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/mm/cma.c b/mm/cma.c index fde706e..0813599 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -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; @@ -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, 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 (;;) { 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; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
