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Subject[PATCH] direct-dma: WARN_ON_ONCE when the page is not addressable by device's coherent_dma_mask
Date
From: JohnHsu <john.hsu@mediatek.com>

The dma_direct_alloc() may return null in some cases. For example, the
allocated page is not addressable for the device's coherent_dma_mask,
and the allocated page will be assigned to null.

This patch can WARN_ON_ONCE() when the returned page is null in
dma_direct_alloc. It helps the developers position the root cause of
allocation failure rapidly.

Signed-off-by: JohnHsu <john.hsu@mediatek.com>
---
kernel/dma/direct.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 9596ae1aa0da..a73b8ad1ef9e 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -156,6 +156,8 @@ static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
}
}

+ WARN_ON_ONCE(!page);
+
return page;
}

--
2.18.0

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