Re: [PATCH 3/5] udmabuf: fix vmap_udmabuf error page set

[Christian König <christian.koenig@xxxxxxx>]

Am 01.08.24 um 12:45 schrieb Huan Yang:
> Currently vmap_udmabuf set page's array by each folio.
> But, ubuf->folios is only contain's the folio's head page.
>
> That mean we repeatedly mapped the folio head page to the vmalloc area.
>
> This patch fix it, set each folio's page correct, so that pages array
> contains right page, and then map into vmalloc area
>
> Signed-off-by: Huan Yang <link@xxxxxxxx>
> ---
>   drivers/dma-buf/udmabuf.c | 17 +++++++++++++----
>   1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
> index a915714c5dce..7ed532342d7f 100644
> --- a/drivers/dma-buf/udmabuf.c
> +++ b/drivers/dma-buf/udmabuf.c
> @@ -77,18 +77,27 @@ static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
>   static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
>   {
>   	struct udmabuf *ubuf = buf->priv;
> -	struct page **pages;
> +	struct page **pages, **tmp;
> +	struct sg_table *sg = ubuf->sg;
> +	struct sg_page_iter piter;
>   	void *vaddr;
> -	pgoff_t pg;
>   
>   	dma_resv_assert_held(buf->resv);
>   
> +	if (!sg) {
> +		sg = get_sg_table(NULL, buf, 0);
> +		if (IS_ERR(sg))
> +			return PTR_ERR(sg);
> +		ubuf->sg = sg;
> +	}
> +
>   	pages = kvmalloc_array(ubuf->pagecount, sizeof(*pages), GFP_KERNEL);
>   	if (!pages)
>   		return -ENOMEM;
> +	tmp = pages;
>   
> -	for (pg = 0; pg < ubuf->pagecount; pg++)
> -		pages[pg] = &ubuf->folios[pg]->page;
> +	for_each_sgtable_page(sg, &piter, 0)
> +		*tmp++ = sg_page_iter_page(&piter);

Again don't abuse the sg table for that!

Regards,
Christian.

>   
>   	vaddr = vm_map_ram(pages, ubuf->pagecount, -1);
>   	kvfree(pages);