On 2020/01/08 10:25, Ming Lei wrote:
> Commit 429120f3df2d starts to take account of segment's start dma address
> when computing max segment size, and data type of 'unsigned long'
> is used to do that. However, the segment mask may be 0xffffffff, so
> the figured out segment size may be overflowed because DMA address can
> be 64bit on 32bit arch.
>
> Fixes the issue by using 'unsigned long long' to compute max segment
> size.
>
> Fixes: 429120f3df2d ("block: fix splitting segments on boundary masks")
> Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> block/blk-merge.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-merge.c b/block/blk-merge.c
> index 347782a24a35..b0fcc72594cb 100644
> --- a/block/blk-merge.c
> +++ b/block/blk-merge.c
> @@ -159,12 +159,12 @@ static inline unsigned get_max_io_size(struct request_queue *q,
>
> static inline unsigned get_max_segment_size(const struct request_queue *q,
> struct page *start_page,
> - unsigned long offset)
> + unsigned long long offset)
> {
> unsigned long mask = queue_segment_boundary(q);
>
> offset = mask & (page_to_phys(start_page) + offset);
Shouldn't mask be an unsigned long long too for this to give the
expected correct result ?
> - return min_t(unsigned long, mask - offset + 1,
> + return min_t(unsigned long long, mask - offset + 1,
> queue_max_segment_size(q));
> }
>
>
--
Damien Le Moal
Western Digital Research
