Re: [PATCH] dma-buf: Fix IOVA offset when linking phys vecs to sgt

[Leon Romanovsky <leon@kernel.org>]

On Thu, Sep 24, 2026 at 02:55:08PM +0800, Yili Zhang wrote:
> The dma_buf_phys_vec_to_sgt() routine links every physical range into
> the allocated IOVA space at offset zero instead of advancing the offset
> by the already mapped length. This breaks the THRU_HOST_BRIDGE flow
> whenever phys_vec contains more than one entry: the second and
> subsequent dma_iova_link() calls try to install mappings on top of
> PTEs that already exist, which fails and makes the whole conversion
> return an error.
> 
> Fix it by passing the accumulated mapped_len as the IOVA offset. This
> matches the pattern used by all other dma_iova_link() callers and is
> consistent with the rest of the function: dma_iova_sync() and the
> error path in dma_iova_destroy() both operate on the [0, mapped_len)
> prefix of the IOVA space, which assumes that the ranges were linked
> contiguously starting at offset 0.
> 
> Fixes: 3aa31a8bb11e ("dma-buf: provide phys_vec to scatter-gather mapping routine")
> Cc: stable@vger.kernel.org
> Signed-off-by: Yili Zhang <zhangyili01@baidu.com>
> ---
>  drivers/dma-buf/dma-buf-mapping.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Thanks,
Reviewed-by: Leon Romanovsky <leon@kernel.org>