Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753449AbdDKDSM (ORCPT ); Mon, 10 Apr 2017 23:18:12 -0400 Received: from mail-pg0-f68.google.com ([74.125.83.68]:33728 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753277AbdDKDSI (ORCPT ); Mon, 10 Apr 2017 23:18:08 -0400 From: js1304@gmail.com X-Google-Original-From: iamjoonsoo.kim@lge.com To: Andrew Morton Cc: Rik van Riel , Johannes Weiner , mgorman@techsingularity.net, Laura Abbott , Minchan Kim , Marek Szyprowski , Michal Nazarewicz , "Aneesh Kumar K . V" , Vlastimil Babka , Russell King , Will Deacon , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@lge.com, Joonsoo Kim Subject: [PATCH v7 7/7] ARM: CMA: avoid re-mapping CMA region if CONFIG_HIGHMEM Date: Tue, 11 Apr 2017 12:17:20 +0900 Message-Id: <1491880640-9944-8-git-send-email-iamjoonsoo.kim@lge.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1491880640-9944-1-git-send-email-iamjoonsoo.kim@lge.com> References: <1491880640-9944-1-git-send-email-iamjoonsoo.kim@lge.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1326 Lines: 38 From: Joonsoo Kim CMA region is now managed by the separate zone, ZONE_CMA, to fix many MM related problems. In this implementation, it is possible that ZONE_CMA contains two CMA regions that are on the both, lowmem and highmem, respectively. To handle this case properly, ZONE_CMA is considered as highmem. In dma_contiguous_remap(), mapping for CMA region on lowmem is cleared and remapped for DMA, but, in the new CMA implementation, remap isn't needed since the region is considered as highmem. And, remap should not be allowed since it would cause cache problems. So, this patch disables it. Signed-off-by: Joonsoo Kim --- arch/arm/mm/dma-mapping.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 475811f..377053a 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -506,7 +506,12 @@ void __init dma_contiguous_remap(void) flush_tlb_kernel_range(__phys_to_virt(start), __phys_to_virt(end)); - iotable_init(&map, 1); + /* + * For highmem system, all the memory in CMA region will be + * considered as highmem, therefore, re-mapping isn't required. + */ + if (!IS_ENABLED(CONFIG_HIGHMEM)) + iotable_init(&map, 1); } } -- 2.7.4