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 <[email protected]> Cc: Konrad Rzeszutek Wilk <[email protected]> Cc: David Woodhouse <[email protected]> Cc: Don Dutile <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Andi Kleen <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: Akinobu Mita <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
