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,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C6089C433E6 for ; Thu, 7 Jan 2021 21:56:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AAA0235FF for ; Thu, 7 Jan 2021 21:56:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728174AbhAGVzx (ORCPT ); Thu, 7 Jan 2021 16:55:53 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:33770 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727897AbhAGVzw (ORCPT ); Thu, 7 Jan 2021 16:55:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610056466; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=jf+u3wtvkVsWkUtVZ2oXqwZM36Cv7Ul38kjJceyKnzM=; b=eB6QX7bBeg61aYN324qil9I14QUySZYb3tEd3jlS23i3HMsyZf6eMCtkOskv5NbfR2sacP 8b2zftv7ukvy1L1QE+fwuyQnZ8CJHkKLjWiWZercxF0TyhcYgfkM1IjdWZQlfh5sIa0UCJ o/kfxmtL5L3CGFi29ptMgXtzY3m/5Cc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-475-fkTxhE-jOu2MkpBUJBayLA-1; Thu, 07 Jan 2021 16:54:24 -0500 X-MC-Unique: fkTxhE-jOu2MkpBUJBayLA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B3852800D55; Thu, 7 Jan 2021 21:54:21 +0000 (UTC) Received: from mail (ovpn-112-222.rdu2.redhat.com [10.10.112.222]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 87AD962A22; Thu, 7 Jan 2021 21:54:14 +0000 (UTC) Date: Thu, 7 Jan 2021 16:54:13 -0500 From: Andrea Arcangeli To: Linus Torvalds Cc: Jason Gunthorpe , Linux-MM , Linux Kernel Mailing List , Yu Zhao , Andy Lutomirski , Peter Xu , Pavel Emelyanov , Mike Kravetz , Mike Rapoport , Minchan Kim , Will Deacon , Peter Zijlstra , Hugh Dickins , "Kirill A. Shutemov" , Matthew Wilcox , Oleg Nesterov , Jann Horn , Kees Cook , John Hubbard , Leon Romanovsky , Jan Kara , Kirill Tkhai Subject: Re: [PATCH 0/2] page_count can't be used to decide when wp_page_copy Message-ID: References: <20210107200402.31095-1-aarcange@redhat.com> <20210107202525.GD504133@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.0.4 (2020-12-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 07, 2021 at 12:32:09PM -0800, Linus Torvalds wrote: > I think Andrea is blinded by his own love for UFFDIO: when I do a > debian codesearch for UFFDIO_WRITEPROTECT, all it finds is the kernel > and strace (and the qemu copies of the kernel headers). For the record, I feel obliged to reiterate I'm thinking purely in clear_refs terms here. It'd be great if we can only focus on clear_refs_write and nothing else. Like I said earlier, whatever way clear_refs/softdirty copes with do_wp_page, uffd-wp can do the identical thing so, uffd-wp is effectively irrelevant in this whole discussion. Clear-refs/softdirty predates uffd-wp by several years too. Thanks, Andrea