Re: [PATCH 1/1] mm: Fix struct page layout on 32-bit systems
From: Matthew Wilcox <willy@infradead.org>
Date: 2021-04-15 18:22:44
Also in:
linux-mips, linux-mm, linuxppc-dev, lkml, netdev
On Thu, Apr 15, 2021 at 08:08:32PM +0200, Jesper Dangaard Brouer wrote:
+static inline
+dma_addr_t page_pool_dma_addr_read(dma_addr_t dma_addr)
+{
+ /* Workaround for storing 64-bit DMA-addr on 32-bit machines in struct
+ * page. The page->dma_addr share area with page->compound_head which
+ * use bit zero to mark compound pages. This is okay, as DMA-addr are
+ * aligned pointers which have bit zero cleared.
+ *
+ * In the 32-bit case, page->compound_head is 32-bit. Thus, when
+ * dma_addr_t is 64-bit it will be located in top 32-bit. Solve by
+ * swapping dma_addr 32-bit segments.
+ */
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT#if defined(CONFIG_ARCH_DMA_ADDR_T_64BIT) && defined(__BIG_ENDIAN) otherwise you'll create the problem on ARM that you're avoiding on PPC ... I think you want to delete the word '_read' from this function name because you're using it for both read and write. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel