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=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6DC78C4361B for ; Wed, 9 Dec 2020 20:33:44 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 1519022B39 for ; Wed, 9 Dec 2020 20:33:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1519022B39 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=vGCsIBfOBl/NxO6FSpmrZhqXDswz+vCMepufh8EblxM=; b=hAmgY69CbdpG1812V+yUO9ISG bbHFHSJ2Bj79z3O9/lwmv4x1UDGoq2Ak1unBav4TJEFUs+guZDF9zMkfhApfVjEJ0Udzv7TdfNRcK zmFYPU9M2vl5W/72K/VNHjqLPtBAPFU+RzogRlwp43+QNk+7OapLffFoPF9fZ+5nxymvV1keCJLk9 HLFvl/Y+EC/vhqcdl9crH3jzVuWTURBvOYU1xbJy92QccwcH+Xh9o9wOd+zCVhBkiaWbHUOCEGJLU wrf1f1D81fQEP6CPUQ6wCeSo6K3UkFoXdKUcENOZ0Vgktv8XEgads82DrnOLfBOBMNWVf/kKBPqD/ qVdGeuboQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kn68J-00051J-Cz; Wed, 09 Dec 2020 20:32:20 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kn686-0004yF-VK for linux-arm-kernel@merlin.infradead.org; Wed, 09 Dec 2020 20:32:07 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=bGzrld7wr84RrSgEszhR+wmk08YFGa6cLi6pnZc4i/0=; b=QaMIoLxvrAk+bVYa5OQVotE5Fc Z1ucapu5XB9I19/2+q9oJ/oXw2s4AAf+/aFypyM5ukgfHHzhsxu6bhWSLEJMll9S65wTjSLPtvU4Q e3xF3Y+A/Oef0602EVYxB4cYNjv1IUBbj8FSla0mNhJ217jHOFm/NgN3bjRhaqxtxxC45shK4lpYo rDnhULs6H5LISfoOOlofa/K5CiZBMyRux/qMHXB5I/9VkXhZKIpLHBs1Lp07P/Do1fCzf/jq9hRUY vQL3G487WOceGg6FvaaVdigeo4TmuwPaKnajJY6ROPQz3AzNouMSTE2HOQYguKRofkVBoJvrWdRCq vjhcjcxg==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kn683-0007vi-5V; Wed, 09 Dec 2020 20:32:03 +0000 Date: Wed, 9 Dec 2020 20:32:03 +0000 From: Matthew Wilcox To: Linus Torvalds Subject: Re: [PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting Message-ID: <20201209203203.GU7338@casper.infradead.org> References: <20201209163950.8494-1-will@kernel.org> <20201209163950.8494-2-will@kernel.org> <20201209184049.GA8778@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Android Kernel Team , Jan Kara , Minchan Kim , Catalin Marinas , Linux Kernel Mailing List , Linux-MM , Vinayak Menon , "Kirill A . Shutemov" , Andrew Morton , Will Deacon , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Dec 09, 2020 at 11:04:13AM -0800, Linus Torvalds wrote: > In particular, it made it a nightmare to read what do_fault_around() > does: it does that odd > > if (pmd_none(*vmf->pmd)) { > vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm); > > and then it calls ->map_pages() (which is always filemap_map_pages(), > except for xfs, where it is also always filemap_map_pages but it takes > a lock first). ... which is wrong. Dave's paranoia around other people introducing bugs into XFS made him do this, but we should revert cd647d5651c0b0deaa26c1acb9e1789437ba9bc7. Those operations he's worried about are protected by the page lock. If a filesystem has put an Uptodate page into the page cache, the rest of the kernel can read it without telling the filesystem. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel