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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 65858C17441 for ; Mon, 11 Nov 2019 16:25:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 30B4821925 for ; Mon, 11 Nov 2019 16:25:07 +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="Peyngf2b" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727016AbfKKQZG (ORCPT ); Mon, 11 Nov 2019 11:25:06 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:55388 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726845AbfKKQZD (ORCPT ); Mon, 11 Nov 2019 11:25:03 -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=xpsjH3Rxk+PTzoxkOgZp7C1flZE/0kiFWtXlSW8zmmw=; b=Peyngf2bhOnRCdtwxQx45nP8t wAM5uTHozveypsI8OvzwXiRStp/WogTr0roVN/uKHuLazBH7c+mWXnXqQ1PKU5tSSg1e3alIDQiv3 FoYLONj0SfEZQMbaDMmpbxCW5xcYZ9L1SnHvEHDzhRtO7O0d7aMOcu56vmmClKNhy0qMGroZpe07j g0d71Zzb1txtXYa9dO7Wuxk56P3CgfiqUMc+4tpfGEmKjdkM/OmNWYfloVPA/ijo8jtYfxjeSq4E8 eeVarnc5boRMwTbtMWZ2BRbavAOznWvd4Qfnl+WCs5qe+IPj7AwPuiJsA1G1sHW4F1KsiGV/oZmhZ fSLdpIETw==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUCUv-0001T1-CH; Mon, 11 Nov 2019 16:25:01 +0000 Date: Mon, 11 Nov 2019 08:25:01 -0800 From: Christoph Hellwig To: Konstantin Khlebnikov Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Alexander Viro , David Howells , Linus Torvalds , Andy Lutomirski , Miklos Szeredi Subject: Re: [PATCH] fs/splice: ignore flag SPLICE_F_GIFT in syscall vmsplice Message-ID: <20191111162501.GB24952@infradead.org> References: <157338008330.5347.7117089871769008055.stgit@buzz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <157338008330.5347.7117089871769008055.stgit@buzz> User-Agent: Mutt/1.12.1 (2019-06-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Nov 10, 2019 at 01:01:23PM +0300, Konstantin Khlebnikov wrote: > Generic support of flag SPLICE_F_MOVE in syscall splice was removed in > kernel 2.6.21 commit 485ddb4b9741 ("1/2 splice: dont steal"). > Infrastructure stay intact and this feature may came back. > At least driver or filesystem could provide own implementation. > > But stealing mapped pages from userspace never worked and is very > unlikely that will ever make sense due to unmapping overhead. > Also lru handling is broken if gifted anon page spliced into file. > > Let's seal entry point for marking page as a gift in vmsplice. Please kill off PIPE_BUF_FLAG_GIFT entirely, there is no need to keep dead code around. Anyone who cares enough can resurrect it from git history.