Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751818AbbBMDcp (ORCPT ); Thu, 12 Feb 2015 22:32:45 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:43489 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751468AbbBMDco (ORCPT ); Thu, 12 Feb 2015 22:32:44 -0500 Date: Fri, 13 Feb 2015 03:32:43 +0000 From: Will Deacon To: Alexandre Courbot Cc: Arnd Bergmann , Russell King , Marek Szyprowski , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Alexandre Courbot Subject: Re: [PATCH RESEND] ARM: DMA: Fix kzalloc flags in __iommu_alloc_buffer() Message-ID: <20150213033243.GC961@arm.com> References: <1423645301-709-1-git-send-email-acourbot@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1423645301-709-1-git-send-email-acourbot@nvidia.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1807 Lines: 51 On Wed, Feb 11, 2015 at 09:01:41AM +0000, Alexandre Courbot wrote: > There doesn't seem to be any valid reason to allocate the pages array > with the same flags as the buffer itself. Doing so can eventually lead > to the following safeguard in mm/slab.c to be hit: > > BUG_ON(flags & GFP_SLAB_BUG_MASK); nit: I can't actually spot this BUG_ON in the kernel. > This happens when buffers are allocated with __GFP_DMA32 or > __GFP_HIGHMEM. > > Fix this by allocating the pages array with GFP_KERNEL to follow what is > done elsewhere in this file. Using GFP_KERNEL in __iommu_alloc_buffer() > is safe because atomic allocations are handled by __iommu_alloc_atomic(). > > Signed-off-by: Alexandre Courbot > Cc: Arnd Bergmann > Cc: Marek Szyprowski > Cc: Russell King > Acked-by: Marek Szyprowski > --- > arch/arm/mm/dma-mapping.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index 903dba0..170a116 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -1106,7 +1106,7 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t size, > int i = 0; > > if (array_size <= PAGE_SIZE) > - pages = kzalloc(array_size, gfp); > + pages = kzalloc(array_size, GFP_KERNEL); > else > pages = vzalloc(array_size); > if (!pages) > -- > 2.3.0 Looks sensible to me: Acked-by: Will Deacon Will -- 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/