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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 50618C43334 for ; Mon, 11 Jul 2022 16:10:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DCCA2940007; Mon, 11 Jul 2022 12:10:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D55388E0002; Mon, 11 Jul 2022 12:10:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BF5D9940007; Mon, 11 Jul 2022 12:10:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id AC0638E0002 for ; Mon, 11 Jul 2022 12:10:05 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 7F3EA60941 for ; Mon, 11 Jul 2022 16:10:05 +0000 (UTC) X-FDA: 79675305570.12.363202B Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf24.hostedemail.com (Postfix) with ESMTP id 7B78118006A for ; Mon, 11 Jul 2022 16:10:02 +0000 (UTC) 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=Yv/cCXkvdegWQDc0hxz1IcTh2VseNOqN5ZAXrrO5pL4=; b=w4sitqjjocX6/l+MMRL0bAQPus 9JhqeNRUeUFV+9Zv4Topm6vzHLXYGRxitIZjDFhIkUDMf6bnFShmm2lwRQGEUARHIv3feODf2/3YM lPCL/vfLxyFvylztBf+4YjDpvcimDMrFv/LtItKz94INmjcreMSMmuFnRN959hKIhnymOcj5K2Vke pRb+/AC14tzroUdWnLwUVVUe6Tm1Oqc3BdzyroJbmj1Nxo+OG4wePwTIwGMluWWh7Oc9hYEnoxqzN s+YV061Nmf+aVWbYRh7bT9uvJACM4qmyA8Z4JW/+4oI4FS2m3DanLulGydwcz+Cjg9NX6sEqTtCSs yw4wv2jA==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1oAvyt-0038S1-Fb; Mon, 11 Jul 2022 16:09:55 +0000 Date: Mon, 11 Jul 2022 09:09:55 -0700 From: Christoph Hellwig To: Li Chen Cc: Christoph Hellwig , Catalin Marinas , Will Deacon , Rob Herring , Frank Rowand , Andrew Morton , linux-arm-kernel , linux-kernel , devicetree , linux-mm Subject: Re: [PATCH 0/4] add struct page and Direct I/O support to reserved memory Message-ID: References: <20220711122459.13773-1-me@linux.beauty> <181ee01d384.b809bd01412268.496620746959082770@linux.beauty> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <181ee01d384.b809bd01412268.496620746959082770@linux.beauty> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1657555803; a=rsa-sha256; cv=none; b=e9/g0LtKpUwushSqnLwDlDQq4naeC4VAIa/Fty3MfLgOfBxou0RyfTJCJMMe+obQY6vdfV 0rnDcsAATjBzZFaxAcW2EfAX+AX3kq/1OVoRidM6ulLdvb/B4Wr8h0gdYuI4Qtp7U55iiR 6mBSYlTLhrTZ13A4wov5YA9RMfDUQC4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1657555803; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Yv/cCXkvdegWQDc0hxz1IcTh2VseNOqN5ZAXrrO5pL4=; b=aRJ91mhEU3njFerKplksURih1jH0MAvkUXl78z0NXW0CfMgSzUdabiG08wXr3GDlW/qC8+ ALGSo7mQJ7Mq38GoFs/7dIjvgZbMkt6eUMv3/HGc81nUiBO9tMPX76u9oGFf5stwxGi8PV 5C44tuATtXjzy5rISPciQNMHYamqGIM= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=w4sitqjj; dmarc=none; spf=none (imf24.hostedemail.com: domain of BATV+f255caa5280b39f3ab8c+6896+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+f255caa5280b39f3ab8c+6896+infradead.org+hch@bombadil.srs.infradead.org Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=w4sitqjj; dmarc=none; spf=none (imf24.hostedemail.com: domain of BATV+f255caa5280b39f3ab8c+6896+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+f255caa5280b39f3ab8c+6896+infradead.org+hch@bombadil.srs.infradead.org X-Rspamd-Server: rspam03 X-Stat-Signature: akfp7zs94q5zx9951ontptowfer43hw5 X-Rspamd-Queue-Id: 7B78118006A X-Rspam-User: X-HE-Tag: 1657555802-349035 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, Jul 12, 2022 at 12:05:06AM +0800, Li Chen wrote: > My use case has been stated in the cover letter, but our driver is not ready for upstream yet. Which means we can't review the use case. I'd suggest you come back when you submit your driver. > With DMA allocator, we can access buffer in kernel space, not userspace, however, this patch Take a look at dma_mmap_* on how to map DMA coherent allocations to usersapce. This is of course easily possible.