Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7422C433F5 for ; Tue, 16 Nov 2021 00:29:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2353619E1 for ; Tue, 16 Nov 2021 00:29:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344441AbhKPAcb (ORCPT ); Mon, 15 Nov 2021 19:32:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345463AbhKOT2b (ORCPT ); Mon, 15 Nov 2021 14:28:31 -0500 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D3353C043193; Mon, 15 Nov 2021 10:53:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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; bh=WBVQU7ONb1dg6gbZK1HaW1EBdo6qodk77XckevyZUq4=; b=G/na0F58vH4bDXGufMVfFBLv8U EBlW/VxENPOy30Ge109XsLBySAMwiYYn6wINE/Lazu4XfJOCGRrbyrbZm5TdkjMRO4og74pon7gHc iPo+KcylzeKLXXdFXDNW6nx4c5QV9qPzTEO0cif72PSetQjUUOV6nqQfL9kfwXrjkvkfJ7wB7INa9 2+LdQS7lxEOqHpiktwiGvQ41IMClQ4QDQx6kEiBV4smBeQsNtFIx62xe66y70Oxi8a1HJBGJE3ffg Qt+MMAOYbVye9yo6ydzuF7d+1u+nbYC6oLSMEqFljNkfxHZrbxtgM5dyEgq+bbmxalJuJ4p4xGeiL EVnbX77w==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mmh6O-00GmMZ-7i; Mon, 15 Nov 2021 18:53:12 +0000 Date: Mon, 15 Nov 2021 10:53:12 -0800 From: Christoph Hellwig To: Ilias Apalodimas Cc: Christoph Hellwig , Yunsheng Lin , Guillaume Tucker , davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linuxarm@openeuler.org, hawk@kernel.org, akpm@linux-foundation.org, peterz@infradead.org, will@kernel.org, jhubbard@nvidia.com, yuzhao@google.com, mcroce@microsoft.com, fenghua.yu@intel.com, feng.tang@intel.com, jgg@ziepe.ca, aarcange@redhat.com, guro@fb.com, "kernelci@groups.io" Subject: Re: [PATCH net-next v6] page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA Message-ID: References: <20211013091920.1106-1-linyunsheng@huawei.com> <1090744a-3de6-1dc2-5efe-b7caae45223a@huawei.com> <644e10ca-87b8-b553-db96-984c0b2c6da1@collabora.com> <93173400-1d37-09ed-57ef-931550b5a582@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 15, 2021 at 08:48:30PM +0200, Ilias Apalodimas wrote: > page_pool (the API in question), apart from allocating memory can manage > the mappings for you. However while doing so it stores some parts (incl > the dma addr) in struct page. The code in there could be simplified if > we skipped support of the 'mapping' feature for 32-bit architectures with > 64-bit DMA. We thought no driver was using the mapping feature (on 32bits) > and cleaned up that part, but apparently we missed > '32-bit -- LPAE -- page pool manages DMA mappings' It is a very common configuration on various architectures, so I fear you'll have to support it and undo the cleanup.