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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 85601C2D0EA for ; Wed, 8 Apr 2020 15:42:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5C6812072F for ; Wed, 8 Apr 2020 15:42:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5C6812072F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 08C148E000D; Wed, 8 Apr 2020 11:42:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 03D788E0006; Wed, 8 Apr 2020 11:42:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E93718E000D; Wed, 8 Apr 2020 11:42:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0185.hostedemail.com [216.40.44.185]) by kanga.kvack.org (Postfix) with ESMTP id CDFA18E0006 for ; Wed, 8 Apr 2020 11:42:28 -0400 (EDT) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 90298181AEF10 for ; Wed, 8 Apr 2020 15:42:28 +0000 (UTC) X-FDA: 76685104776.19.quiet51_4fc3065122b3f X-HE-Tag: quiet51_4fc3065122b3f X-Filterd-Recvd-Size: 1706 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf06.hostedemail.com (Postfix) with ESMTP for ; Wed, 8 Apr 2020 15:42:27 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 313AE68C4E; Wed, 8 Apr 2020 17:42:26 +0200 (CEST) Date: Wed, 8 Apr 2020 17:42:25 +0200 From: Christoph Hellwig To: Hillf Danton Cc: Christoph Hellwig , Andrew Morton , linux-mm@kvack.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 04/28] dma-mapping: use vmap insted of reimplementing it Message-ID: <20200408154225.GA28676@lst.de> References: <20200408115926.1467567-1-hch@lst.de> <20200408131736.9532-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200408131736.9532-1-hdanton@sina.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Apr 08, 2020 at 09:17:36PM +0800, Hillf Danton wrote: > > @@ -62,24 +42,20 @@ void *dma_common_pages_remap(struct page **pages, size_t size, > > void *dma_common_contiguous_remap(struct page *page, size_t size, > > pgprot_t prot, const void *caller) > > { > > - int i; > > + int count = size >> PAGE_SHIFT; > > struct page **pages; > > - struct vm_struct *area; > > + void *vaddr; > > + int i; > > > > - pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL); > > + pages = kmalloc_array(count, sizeof(struct page *), GFP_KERNEL); > > Is it making sense to vmalloc pages as long as array size is bigger than > PAGE_SIZE? Maybe, maybe not. But it certainly doesn't fit this series.