Calling dma_alloc_coherent() with __GFP_ZERO must return zeroed memory.
But when the contiguous memory allocator (CMA) is enabled on x86 and
the memory region is allocated by dma_alloc_from_contiguous(), it
doesn't return zeroed memory. Because dma_generic_alloc_coherent()
forgot to fill the memory region with zero if it was allocated by
dma_alloc_from_contiguous()
Most implementations of dma_alloc_coherent() return zeroed memory
regardless of whether __GFP_ZERO is specified. So this fixes it by
unconditionally zeroing the allocated memory region.
Cc: Marek Szyprowski <m.szyprow...@samsung.com>
Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Cc: David Woodhouse <dw...@infradead.org>
Cc: Don Dutile <ddut...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Andi Kleen <a...@firstfloor.org>
Cc: x...@kernel.org
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Akinobu Mita <akinobu.m...@gmail.com>
---
New patch from this version
arch/x86/kernel/pci-dma.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 872079a..9644405 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -97,7 +97,6 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t
size,
dma_mask = dma_alloc_coherent_mask(dev, flag);
- flag |= __GFP_ZERO;
again:
page = NULL;
if (!(flag & GFP_ATOMIC))
@@ -118,7 +117,7 @@ again:
return NULL;
}
-
+ memset(page_address(page), 0, size);
*dma_addr = addr;
return page_address(page);
}
--
1.8.3.2
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