From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753947AbaESJOZ (ORCPT ); Mon, 19 May 2014 05:14:25 -0400 Received: from LGEMRELSE6Q.lge.com ([156.147.1.121]:58277 "EHLO lgemrelse6q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753846AbaESJOV (ORCPT ); Mon, 19 May 2014 05:14:21 -0400 X-Original-SENDERIP: 10.178.33.69 X-Original-MAILFROM: gioh.kim@lge.com Message-ID: <5379CB66.7090607@lge.com> Date: Mon, 19 May 2014 18:14:14 +0900 From: Gioh Kim User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Joonsoo Kim CC: Michal Nazarewicz , Minchan Kim , Andrew Morton , Rik van Riel , Laura Abbott , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Heesub Shin , Mel Gorman , Johannes Weiner , Marek Szyprowski , =?UTF-8?B?7J206rG07Zi4?= , gurugio@gmail.com Subject: Re: [RFC][PATCH] CMA: drivers/base/Kconfig: restrict CMA size to non-zero value References: <1399509144-8898-1-git-send-email-iamjoonsoo.kim@lge.com> <1399509144-8898-3-git-send-email-iamjoonsoo.kim@lge.com> <20140513030057.GC32092@bbox> <20140515015301.GA10116@js1304-P5Q-DELUXE> <5375C619.8010501@lge.com> <537962A0.4090600@lge.com> <20140519055527.GA24099@js1304-P5Q-DELUXE> In-Reply-To: <20140519055527.GA24099@js1304-P5Q-DELUXE> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In __dma_alloc function, your patch can make __alloc_from_pool work. But __alloc_from_contiguous doesn't work. Therefore __dma_alloc sometimes works and sometimes not according to the gfp(__GFP_WAIT) flag. Do I understand correctly? I think __dma_alloc should work consistently. Both of __alloc_from_contiguous and __alloc_from_pool should work together, or both of them do not work. 2014-05-19 오후 2:55, Joonsoo Kim 쓴 글: > On Mon, May 19, 2014 at 10:47:12AM +0900, Gioh Kim wrote: >> Thank you for your advice. I didn't notice it. >> >> I'm adding followings according to your advice: >> >> - range restrict for CMA_SIZE_MBYTES and *CMA_SIZE_PERCENTAGE* >> I think this can prevent the wrong kernel option. >> >> - change size_cmdline into default value SZ_16M >> I am not sure this can prevent if cma=0 cmdline option is also with base and limit options. > > Hello, > > I think that this problem is originated from atomic_pool_init(). > If configured coherent_pool size is larger than default cma size, > it can be failed even if this patch is applied. > > How about below patch? > It uses fallback allocation if CMA is failed. > > Thanks. > > -----------------8<--------------------- > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index 6b00be1..2909ab9 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -379,7 +379,7 @@ static int __init atomic_pool_init(void) > unsigned long *bitmap; > struct page *page; > struct page **pages; > - void *ptr; > + void *ptr = NULL; > int bitmap_size = BITS_TO_LONGS(nr_pages) * sizeof(long); > > bitmap = kzalloc(bitmap_size, GFP_KERNEL); > @@ -393,7 +393,7 @@ static int __init atomic_pool_init(void) > if (IS_ENABLED(CONFIG_DMA_CMA)) > ptr = __alloc_from_contiguous(NULL, pool->size, prot, &page, > atomic_pool_init); > - else > + if (!ptr) > ptr = __alloc_remap_buffer(NULL, pool->size, gfp, prot, &page, > atomic_pool_init); > if (ptr) { > >