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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,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 05FF8C43387 for ; Wed, 19 Dec 2018 07:09:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C840421841 for ; Wed, 19 Dec 2018 07:09:22 +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="fzX09TCd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727904AbeLSHJW (ORCPT ); Wed, 19 Dec 2018 02:09:22 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:35206 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728051AbeLSHJR (ORCPT ); Wed, 19 Dec 2018 02:09:17 -0500 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=/KC9DHMjwbOpXhQULiC+bGxJFMoZGP8G7cGQ95/QabA=; b=fzX09TCdB0RNQPNuytVszcw2o xWE3VbUouxsxmIxZxo3vpW8mbznVEpBRKBFZcOewcZYd/VkwzaboqfyRXUTW8vfgQIaXJdrBk6bN6 9BJxOVZA2ybK3tuF0x9xh4KDqSRZnbCpz84l/HoexuiDoL6H9AS+u3IPiq39ZtEG3fUXQn/ExLgNM YlG/9Xvq9k7YZtK39Q7lwKh2lJ792HzjtbR16QQqu7za3h4i93w9VXm/IxQ8npru46Pab7jbB7xJJ AW0ivDlPKgEo/FwDVNtvG1Q6cji6gfBgoQILMd9cwVygsBOHnEwEfVfgQ7T1XKwasLfTrjWo6mzqP lUizwtyCQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gZVym-0001Ic-2e; Wed, 19 Dec 2018 07:09:16 +0000 Date: Tue, 18 Dec 2018 23:09:15 -0800 From: Christoph Hellwig To: Eric Biggers Cc: Christoph Hellwig , linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra , Linus Torvalds Subject: Re: [PATCH v2 01/12] fs-verity: add a documentation file Message-ID: <20181219070915.GA2628@infradead.org> References: <20181101225230.88058-1-ebiggers@kernel.org> <20181101225230.88058-2-ebiggers@kernel.org> <20181212091406.GA31723@infradead.org> <20181212202609.GA193967@gmail.com> <20181213202249.GA3797@infradead.org> <20181214044802.GA681@sol.localdomain> <20181217164949.GA18626@infradead.org> <20181217183205.GA141684@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181217183205.GA141684@gmail.com> 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-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Mon, Dec 17, 2018 at 10:32:06AM -0800, Eric Biggers wrote: > I don't see how that helps. The Merkle tree can still be too large to fit in > memory. In the worst case, it might not even fit in the address space. And I > don't see how get_user_pages() helps either over just copy_from_user(); what are > you proposing to do with the pages after getting them, exactly? Write them out to a file system specific area on the media. Note that get_user_pages is indeed not going to work if you run out of address space, but that seems like an odd use case. Out of of memory is not an issue as we generally iterate over a small number of pages for each individual get_user_pages call.