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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 73076C433FE for ; Tue, 21 Sep 2021 09:34:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E893A61168 for ; Tue, 21 Sep 2021 09:34:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E893A61168 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 588E56B0071; Tue, 21 Sep 2021 05:34:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 538196B0072; Tue, 21 Sep 2021 05:34:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 400086B0073; Tue, 21 Sep 2021 05:34:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0144.hostedemail.com [216.40.44.144]) by kanga.kvack.org (Postfix) with ESMTP id 32B886B0071 for ; Tue, 21 Sep 2021 05:34:19 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id CAF402CBD2 for ; Tue, 21 Sep 2021 09:34:18 +0000 (UTC) X-FDA: 78611069796.22.9F054AC Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf15.hostedemail.com (Postfix) with ESMTP id 83E1AD00009B for ; Tue, 21 Sep 2021 09:34:18 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 9D68961131; Tue, 21 Sep 2021 09:34:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1632216857; bh=26947zVG9riVqwftMN1dSoamNLEgoqIkp483H/vlQOo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Zo2HL5/V1BbcKSIpxSOBX/zdavkL4LAEANyknHxlliKWMePeJzZr4IeEC/oSTlAYq xMj+dgHL42dCKy96+2Wu4J+KlASIJoo7owJ5j3nG4mnqynPiESYhiWjdd49vSqqN++ 0ZCeYqjlhtTw3fLkQfHAh6iewWUS14jUeFvJupdrrV4Bo+FXTapZvJVk9VC5zxQRNv 7PaU2iomEyzPiSTKr8eQOOuM0OE9XwNEoX+ySL0No88y23eoUwj9XVk3/eIgpo48Gw X5e4Uks97yzbFv3Sdsz5bbAAFMJMKAv14aLh7zxHLMdaa1UylaD0EPl4w0+RE6gUvr oylJ1v4fD8l5w== Date: Tue, 21 Sep 2021 12:34:10 +0300 From: Mike Rapoport To: Christoph Hellwig Cc: Catalin Marinas , David Hildenbrand , Robin Murphy , Alex Bee , Will Deacon , Andrew Morton , Anshuman Khandual , Linux Kernel Mailing List , linux-mm@kvack.org, Linux ARM Subject: Re: [BUG 5.14] arm64/mm: dma memory mapping fails (in some cases) Message-ID: References: <0908ce39-7e30-91fa-68ef-11620f9596ae@arm.com> <60a11eba-2910-3b5f-ef96-97d4556c1596@redhat.com> <20210825102044.GA3420@arm.com> <20210918051843.GA16104@lst.de> <20210921082007.GA29121@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210921082007.GA29121@lst.de> Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="Zo2HL5/V"; spf=pass (imf15.hostedemail.com: domain of rppt@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Stat-Signature: owr1cgty9yp7awy9xpyyhwj7btigxait X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 83E1AD00009B X-HE-Tag: 1632216858-835702 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 Tue, Sep 21, 2021 at 10:20:07AM +0200, Christoph Hellwig wrote: > On Mon, Sep 20, 2021 at 11:57:58AM +0100, Catalin Marinas wrote: > > > As this WARN_ON(pfn_valid()) is only present in dma_map_resource() it's > > > probably safe to drop it entirely. > > > > I agree, we should drop it. IIUC dma_map_resource() does not create any > > kernel mapping to cause problems with attribute aliasing. You'd need a > > prior devm_ioremap_resource() if you want access to that range from the > > CPU side. For arm64 at least, the latter ends up with a > > pfn_is_map_memory() check. > > It doesn't create any new mappings. The only real issue is that it > does the wrong thing for RAM in a way that might not be noticed on > simple (x86/PC) platforms. But if the mapping request was rejected by devm_ioremap_resource() because of an attempt to map RAM, why we would get to dma_map_resource() at all? -- Sincerely yours, Mike.