From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4F9CEC6778A for ; Tue, 24 Jul 2018 18:09:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA48D20874 for ; Tue, 24 Jul 2018 18:09:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="SOjXwZ/j" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EA48D20874 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388531AbeGXTRG (ORCPT ); Tue, 24 Jul 2018 15:17:06 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:43764 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388403AbeGXTRG (ORCPT ); Tue, 24 Jul 2018 15:17:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=3/qR2/s/jkp/x+UEP9487SNsdXRODOQeXau8SvMn+SU=; b=SOjXwZ/j845v1dC4awFyxKiX2 35EzP/JrgdQjSFEwQOWeKCPSSAFB8tNSgD42R/X2niFymtdNDD3kHi6Cg7dWTVnfCeWItyTpgwnD8 BmC4RlvKx5RDARB3Dx6YfjEN4FKYRxW3tKaKLBYsv76qZY1BQAIru4Nz58yAJXX2OcnHe5r7KiyJf NZ5qE9L6txirSmVVQWQ1GpCHH1aX0DGGb3lIX3vPMT8+lH57geU+raVqQ9NK3/OGG9/9ETGjIu4yQ YdxexskzWwo4n4/2qC09dJ1vRDbs5CwcBNtMTYrMS76QN3MT2SghLVrhm1ES9tla1C3QOBKPcia/m CdTUz4k5Q==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1fi1kA-0002Gr-KN; Tue, 24 Jul 2018 18:09:06 +0000 Date: Tue, 24 Jul 2018 11:09:06 -0700 From: Christoph Hellwig To: YueHaibing Cc: linux@armlinux.org.uk, matthias.bgg@gmail.com, vladimir.murzin@arm.com, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, iamjoonsoo.kim@lge.com, robin.murphy@arm.com, treding@nvidia.com, zhongjiang@huawei.com Subject: Re: [PATCH] ARM: dma-mapping: always clear allocated buffers Message-ID: <20180724180906.GA8240@infradead.org> References: <20180724140435.17112-1-yuehaibing@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180724140435.17112-1-yuehaibing@huawei.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 24, 2018 at 10:04:35PM +0800, YueHaibing wrote: > Sean Wang report dma_zalloc_coherent doesn't work as expect on his > armv7,the allocated mem is not zeroed.The reason is __alloc_from_pool > doesn't honor __GFP_ZERO. Please explain the "why" a little more. All the explanations are in the referenced arm64 commit and should be mentioned here as well.