From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964977AbbLHMMx (ORCPT ); Tue, 8 Dec 2015 07:12:53 -0500 Received: from mail-lb0-f179.google.com ([209.85.217.179]:33436 "EHLO mail-lb0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964944AbbLHMMw (ORCPT ); Tue, 8 Dec 2015 07:12:52 -0500 Subject: Re: [PATCH] MIPS: Fix DMA contiguous allocation To: Qais Yousef , linux-mips@linux-mips.org References: <1449569930-2118-1-git-send-email-qais.yousef@imgtec.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, ralf@linux-mips.org, akpm@linux-foundation.org, mgorman@techsingularity.net From: Sergei Shtylyov Message-ID: <5666C941.20209@cogentembedded.com> Date: Tue, 8 Dec 2015 15:12:49 +0300 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <1449569930-2118-1-git-send-email-qais.yousef@imgtec.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/8/2015 1:18 PM, Qais Yousef wrote: > Recent changes to how GFP_ATOMIC is defined seems to have broken the condition > to use mips_alloc_from_contiguous() in mips_dma_alloc_coherent(). > > I couldn't bottom out the exact change but I think it's this one > > d0164adc89f6 (mm, page_alloc: distinguish between being unable to sleep, > unwilling to sleep and avoiding waking kswapd) > > From what I see GFP_ATOMIC has multiple bits set and the check for !(gfp > & GFP_ATOMIC) isn't enough. To verify if the flag is atomic we need to make > sure that (gfp & GFP_ATOMIC) == GFP_ATOMIC to verify that all bits rquired to Required. > satisfy GFP_ATOMIC condition are set. > > Signed-off-by: Qais Yousef > --- > arch/mips/mm/dma-default.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c > index d8117be729a2..d6b8a1445a3a 100644 > --- a/arch/mips/mm/dma-default.c > +++ b/arch/mips/mm/dma-default.c > @@ -145,7 +145,7 @@ static void *mips_dma_alloc_coherent(struct device *dev, size_t size, > > gfp = massage_gfp_flags(dev, gfp); > > - if (IS_ENABLED(CONFIG_DMA_CMA) && !(gfp & GFP_ATOMIC)) > + if (IS_ENABLED(CONFIG_DMA_CMA) && ((gfp & GFP_ATOMIC) != GFP_ATOMIC)) () around != not necessary. [...] MBR, Sergei