Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751634AbaAOUKt (ORCPT ); Wed, 15 Jan 2014 15:10:49 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:41000 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750973AbaAOUKq (ORCPT ); Wed, 15 Jan 2014 15:10:46 -0500 Date: Wed, 15 Jan 2014 15:09:34 -0500 From: Konrad Rzeszutek Wilk To: Akinobu Mita Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Marek Szyprowski , David Woodhouse , Don Dutile , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andi Kleen , x86@kernel.org, iommu@lists.linux-foundation.org Subject: Re: [PATCH v2 1/5] x86: make dma_alloc_coherent() return zeroed memory if CMA is enabled Message-ID: <20140115200934.GC5201@phenom.dumpdata.com> References: <1389708830-5841-1-git-send-email-akinobu.mita@gmail.com> <1389708830-5841-2-git-send-email-akinobu.mita@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1389708830-5841-2-git-send-email-akinobu.mita@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 14, 2014 at 11:13:46PM +0900, Akinobu Mita wrote: > 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() So why not fix it there to return zeroed out memory? > 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 > Cc: Konrad Rzeszutek Wilk > Cc: David Woodhouse > Cc: Don Dutile > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: "H. Peter Anvin" > Cc: Andi Kleen > Cc: x86@kernel.org > Cc: iommu@lists.linux-foundation.org > Signed-off-by: Akinobu Mita > --- > 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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/