dma-direct: don't fail on highmem CMA pages in dma_direct_alloc_pages

When dma_direct_alloc_pages encounters a highmem page it just gives up
currently.  But what we really should do is to try memory using the
page allocator instead - without this platforms with a global highmem
CMA pool will fail all dma_alloc_pages allocations.

Fixes: efa70f2 ("dma-mapping: add a new dma_alloc_pages API")
Reported-by: Mark O'Neill <mao@tumblingdice.co.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>

kernel/dma/direct.c

@@ -115,7 +115,7 @@ static struct page *dma_direct_alloc_swiotlb(struct device *dev, size_t size)
 }
 
 static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
-		gfp_t gfp)
+		gfp_t gfp, bool allow_highmem)
 {
 	int node = dev_to_node(dev);
 	struct page *page = NULL;
@@ -129,9 +129,12 @@ static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
 	gfp |= dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
 					   &phys_limit);
 	page = dma_alloc_contiguous(dev, size, gfp);
-	if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
-		dma_free_contiguous(dev, page, size);
-		page = NULL;
+	if (page) {
+		if (!dma_coherent_ok(dev, page_to_phys(page), size) ||
+		    (!allow_highmem && PageHighMem(page))) {
+			dma_free_contiguous(dev, page, size);
+			page = NULL;
+		}
 	}
 again:
 	if (!page)
@@ -189,7 +192,7 @@ static void *dma_direct_alloc_no_mapping(struct device *dev, size_t size,
 {
 	struct page *page;
 
-	page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO);
+	page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, true);
 	if (!page)
 		return NULL;
 
@@ -262,7 +265,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 		return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
 
 	/* we always manually zero the memory once we are done */
-	page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO);
+	page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, true);
 	if (!page)
 		return NULL;
 
@@ -370,19 +373,9 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
 	if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp))
 		return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
 
-	page = __dma_direct_alloc_pages(dev, size, gfp);
+	page = __dma_direct_alloc_pages(dev, size, gfp, false);
 	if (!page)
 		return NULL;
-	if (PageHighMem(page)) {
-		/*
-		 * Depending on the cma= arguments and per-arch setup
-		 * dma_alloc_contiguous could return highmem pages.
-		 * Without remapping there is no way to return them here,
-		 * so log an error and fail.
-		 */
-		dev_info(dev, "Rejecting highmem page from CMA.\n");
-		goto out_free_pages;
-	}
 
 	ret = page_address(page);
 	if (dma_set_decrypted(dev, ret, size))