The CMA aligned offset calculation is incorrect for non-zero order_per_bit values. For example, if cma->order_per_bit=1, cma->base_pfn= 0x2f800000 and align_order=12, the function returns a value of 0x17c00 instead of 0x400. This patch fixes the CMA aligned offset calculation. Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Danesh Petigara <dpetigara@xxxxxxxxxxxx> Reviewed-by: Gregory Fong <gregory.0xf0@xxxxxxxxx> Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx> --- Changes since v1: - moved comment out of function - removed unused 'alignment' variable v1: https://lkml.org/lkml/2015/2/24/598 mm/cma.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/mm/cma.c b/mm/cma.c index 75016fd..68ecb7a 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -64,15 +64,17 @@ static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order) return (1UL << (align_order - cma->order_per_bit)) - 1; } +/* + * Find a PFN aligned to the specified order and return an offset represented in + * order_per_bits. + */ 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); + + return (ALIGN(cma->base_pfn, (1UL << align_order)) + - cma->base_pfn) >> cma->order_per_bit; } static unsigned long cma_bitmap_maxno(struct cma *cma) -- 1.9.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>