page_pool: use DMA_ATTR_SKIP_CPU_SYNC for DMA mappings (13f16d9d) · Commits · 戴 / test

As pointed out by Alexander Duyck, the DMA mapping done in page_pool needs to use the DMA attribute DMA_ATTR_SKIP_CPU_SYNC. As the principle behind page_pool keeping the pages mapped is that the driver takes over the DMA-sync steps. Reported-by:

Alexander Duyck <alexander.duyck@gmail.com> Signed-off-by:

Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by:

Ilias Apalodimas <ilias.apalodimas@linaro.org> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/page_pool.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -141,9 +141,9 @@ static struct page __page_pool_alloc_pages_slow(struct page_pool pool,
		* into page private data (i.e 32bit cpu with 64bit DMA caps)
		* This mapping is kept for lifetime of page, until leaving pool.
		*/
		dma = dma_map_page(pool->p.dev, page, 0,
		dma = dma_map_page_attrs(pool->p.dev, page, 0,
		(PAGE_SIZE << pool->p.order),
		pool->p.dma_dir);
		pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
		if (dma_mapping_error(pool->p.dev, dma)) {
		put_page(page);
		return NULL;
		@@ -184,8 +184,9 @@ static void __page_pool_clean_page(struct page_pool *pool,

		dma = page->dma_addr;
		/* DMA unmap */
		dma_unmap_page(pool->p.dev, dma,
		PAGE_SIZE << pool->p.order, pool->p.dma_dir);
		dma_unmap_page_attrs(pool->p.dev, dma,
		PAGE_SIZE << pool->p.order, pool->p.dma_dir,
		DMA_ATTR_SKIP_CPU_SYNC);
		page->dma_addr = 0;
		}

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