linux-kernel - [PATCH 3/8] dma-direct check for highmem pages in dma_direct_alloc

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Message-Id: <20200930160917.1234225-4-hch@lst.de>
Date:   Wed, 30 Sep 2020 18:09:12 +0200
From:   Christoph Hellwig <hch@....de>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Tomasz Figa <tfiga@...omium.org>,
        iommu@...ts.linux-foundation.org
Cc:     Robin Murphy <robin.murphy@....com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org
Subject: [PATCH 3/8] dma-direct check for highmem pages in dma_direct_alloc_pages

Check for highmem pages from CMA, just like in the dma_direct_alloc path.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 kernel/dma/direct.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 121a9c1969dd3a..b5f20781d3a96f 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -309,6 +309,17 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
 	page = __dma_direct_alloc_pages(dev, size, gfp);
 	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 (force_dma_unencrypted(dev)) {
 		if (set_memory_decrypted((unsigned long)ret,
-- 
2.28.0