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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 33BAAC433DF for ; Thu, 6 Aug 2020 11:16:06 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3DE4C206B5 for ; Thu, 6 Aug 2020 11:16:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3DE4C206B5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 33DCA8836F; Thu, 6 Aug 2020 05:18:24 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 1o9VNkMwXG6x; Thu, 6 Aug 2020 05:18:22 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id 15B068816A; Thu, 6 Aug 2020 05:18:22 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 0518EC0051; Thu, 6 Aug 2020 05:18:22 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 09266C004C for ; Thu, 6 Aug 2020 05:18:21 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id EC44986C67 for ; Thu, 6 Aug 2020 05:18:20 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id gUBIRiZVRCtL for ; Thu, 6 Aug 2020 05:18:19 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by fraxinus.osuosl.org (Postfix) with ESMTPS id 9794486C51 for ; Thu, 6 Aug 2020 05:18:19 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id AB10868CFE; Thu, 6 Aug 2020 07:18:14 +0200 (CEST) Date: Thu, 6 Aug 2020 07:18:14 +0200 From: Christoph Hellwig To: Nicolas Saenz Julienne Subject: Re: [PATCH v2 2/2] dma-pool: Only allocate from CMA when in same memory zone Message-ID: <20200806051814.GA10143@lst.de> References: <20200803160956.19235-1-nsaenzjulienne@suse.de> <20200803160956.19235-3-nsaenzjulienne@suse.de> <20200804060633.GA7368@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: amit.pundir@linaro.org, linux-kernel@vger.kernel.org, jeremy.linton@arm.com, iommu@lists.linux-foundation.org, linux-rpi-kernel@lists.infradead.org, rientjes@google.com, Robin Murphy , Christoph Hellwig X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Tue, Aug 04, 2020 at 11:43:15AM +0200, Nicolas Saenz Julienne wrote: > > Second I don't see the need (and actually some harm) in preventing GFP_KERNEL > > allocations from dipping into lower CMA areas - something that we did support > > before 5.8 with the single pool. > > My thinking is the least we pressure CMA the better, it's generally scarse, and > it'll not grow as the atomic pools grow. As far as harm is concerned, we now > check addresses for correctness, so we shouldn't run into problems. > > There is a potential case for architectures defining a default CMA but not > defining DMA zones where this could be problematic. But isn't that just plain > abusing CMA? If you need low memory allocations, you should be defining DMA > zones. The latter is pretty much what I expect, as we only support the default and per-device DMA CMAs. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu