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=-7.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_PASS,URIBL_BLOCKED,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 71373C43381 for ; Fri, 15 Mar 2019 09:07:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3CFAA218C3 for ; Fri, 15 Mar 2019 09:07:18 +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="D2sYvTvA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728752AbfCOJHQ (ORCPT ); Fri, 15 Mar 2019 05:07:16 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:34934 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728658AbfCOJGu (ORCPT ); Fri, 15 Mar 2019 05:06:50 -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=dhnvin1A+/DeqhKqw1M209Ghaxo83lMkAF87K2TEozs=; b=D2sYvTvAumK+FL7XrQVQgorza 4cMnFHz2EAvIXuIzRbGbVloAQMtw+9/UzmPIJPqu6AXGHCA+TEsrlSyISslUYYHSbkRc1hdpuksJT j7m0I8BHNdfzii7yIWOdHu7p3SA10ZOJmQK21RMKm5tTiytHg34gSkJ/B9X4VdfvlYYjJfp34vS7X 9w6ZbqIdvKa2+yQB9tYTM4z4ap62L99exHTylNrUwG4MBI4vMq53wdDkvzsDYYle1ekq+LuZoZ8st R55qkSc3KCnSRjaJ7PYkUFL1SQRnLpUzlOrM2Q7xaRqKrrBwtkKki42QGTsYOD7RX8BLO7JmMlxG4 l2C8fzGLA==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1h4inh-0008Du-NK; Fri, 15 Mar 2019 09:06:49 +0000 Date: Fri, 15 Mar 2019 02:06:49 -0700 From: Christoph Hellwig To: John Stultz Cc: lkml , Laura Abbott , Benjamin Gaignard , Greg KH , Sumit Semwal , Liam Mark , Brian Starkey , "Andrew F . Davis" , Chenbo Feng , Alistair Strachan , dri-devel@lists.freedesktop.org Subject: Re: [RFC][PATCH 3/5 v2] dma-buf: heaps: Add system heap to dmabuf heaps Message-ID: <20190315090649.GD4470@infradead.org> References: <1551819273-640-1-git-send-email-john.stultz@linaro.org> <1551819273-640-4-git-send-email-john.stultz@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1551819273-640-4-git-send-email-john.stultz@linaro.org> 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 > + i = sg_alloc_table(table, npages, GFP_KERNEL); > + if (i) > + goto err1; > + for_each_sg(table->sgl, sg, table->nents, i) { > + struct page *page; > + > + page = alloc_page(GFP_KERNEL); > + if (!page) > + goto err2; > + sg_set_page(sg, page, PAGE_SIZE, 0); > + } Given that one if not the primary intent here is to DMA map the memory this is a bad idea, as it might require bounce buffering. What we really want here is something like this: http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-noncoherent-allocator.3 And I wonder if the S/G building should also move into common code instead of being duplicated everywhere. > +static int system_heap_create(void) > +{ > + struct system_heap *sys_heap; > + > + sys_heap = kzalloc(sizeof(*sys_heap), GFP_KERNEL); > + if (!sys_heap) > + return -ENOMEM; > + sys_heap->heap.name = "system_heap"; > + sys_heap->heap.ops = &system_heap_ops; > + > + dma_heap_add(&sys_heap->heap); Why is this dynamically allocated?