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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 BBD67C4724C for ; Fri, 1 May 2020 12:50:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A693421582 for ; Fri, 1 May 2020 12:50:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728639AbgEAMuz (ORCPT ); Fri, 1 May 2020 08:50:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44322 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1728443AbgEAMuz (ORCPT ); Fri, 1 May 2020 08:50:55 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A531C061A0C; Fri, 1 May 2020 05:50:55 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jUV7x-00FtME-PR; Fri, 01 May 2020 12:50:49 +0000 Date: Fri, 1 May 2020 13:50:49 +0100 From: Al Viro To: Christoph Hellwig Cc: Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] exec: open code copy_string_kernel Message-ID: <20200501125049.GL23230@ZenIV.linux.org.uk> References: <20200501104105.2621149-1-hch@lst.de> <20200501104105.2621149-3-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200501104105.2621149-3-hch@lst.de> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, May 01, 2020 at 12:41:05PM +0200, Christoph Hellwig wrote: > Currently copy_string_kernel is just a wrapper around copy_strings that > simplifies the calling conventions and uses set_fs to allow passing a > kernel pointer. But due to the fact the we only need to handle a single > kernel argument pointer, the logic can be sigificantly simplified while > getting rid of the set_fs. I can live with that... BTW, why do we bother with flush_cache_page() (by way of get_arg_page()) here and in copy_strings()? How could *anything* have accessed that page by its address in new mm - what are we trying to flush here?