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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 3F3AFC49ED7 for ; Fri, 13 Sep 2019 12:55:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 13921206BB for ; Fri, 13 Sep 2019 12:55:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="EFAENpnH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387443AbfIMMzK (ORCPT ); Fri, 13 Sep 2019 08:55:10 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:36726 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726771AbfIMMzK (ORCPT ); Fri, 13 Sep 2019 08:55:10 -0400 Received: by mail-wr1-f65.google.com with SMTP id y19so31994560wrd.3 for ; Fri, 13 Sep 2019 05:55:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=cc:subject:to:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=Xh9qvKkaHbrbSRaUE8wvMdjOeOcRk60L7JlLBZQx9jc=; b=EFAENpnHE0IE6f1mk0QYRx4APl+bC8yA5ekmuCm1JrrvILlwmK1eAQaX5yFvFHlUd8 YigdOWHGexF6CGEn2iez+dUp3shz30CUq+395Wu8Vl3Z1Ehv3EgGMXCOrqFpkBeOEhnY fAhAGQCobHORIuk74t4C2VuYxXEYqSWnnJQK3FnFiO7iV+yfXwv3Qc0E1OBa3up2vVHb HseIAFeYC4lq3bJrtmdcolSu1ZD7YOYGf3O6o6Hp5Qzkatv5xatTX9lLMvg2pGhTH5aq sddcS/KL1YnbKzHpy4d18EEfuBeoEgoCodStW5wvPDwIXFOfsKiIqUMNq3B/sFtc5/js bAnw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:cc:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Xh9qvKkaHbrbSRaUE8wvMdjOeOcRk60L7JlLBZQx9jc=; b=ZoyYt2vf8EDY2xDxCdMSvGqWDkboNn4zHMRGCVzWsdULOfsk3vUuBdRQpHcIa7CLcp MTujVtWV+ctf5vZ4BKDgapiQn26RMzwBjB5CsEHMpibr3Zxl4qB/QpUpzGgdb9kEb5Yd IoCTytdRrer06uawNCt6GpIYVGiaRAVxWXtiup3vGs1VZ6XayIZw/1g76ppBfQeEgVow F8etv6PopeOtDdQZW3O/a7WS+X/+OeYdd6ns6kvNYMJpY+qB3pNYiCC5Ge0JJ73V3vQY UKv88U0nC+b3t6VrzbkEeoDYZPOuk/JjGuTQLY153cuOzfuiNOzZcMeS08WQXhxpMR3E 1h7g== X-Gm-Message-State: APjAAAWcaGVO8nDPWvB+OjKQyZJZhIkTWAWhQPgX0ih4QGMPTyPbecXA QY9qvIwhyhm6wwtWy3WvR+50uuyl X-Google-Smtp-Source: APXvYqwahYMHm0z4OSmEdEpYAEYulsEt7efE+tQSR+/1MWOjM0llUWwnYsCg7AuD3QtsfDSwg4aj5Q== X-Received: by 2002:a5d:4b4e:: with SMTP id w14mr11233189wrs.191.1568379308117; Fri, 13 Sep 2019 05:55:08 -0700 (PDT) Received: from [10.0.20.253] ([95.157.63.22]) by smtp.gmail.com with ESMTPSA id f24sm1846067wmb.16.2019.09.13.05.55.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Sep 2019 05:55:07 -0700 (PDT) Cc: mtk.manpages@gmail.com, linux-man@vger.kernel.org Subject: Re: [PATCH] vmsplice.2: SPLICE_F_GIFT became no-op To: Leonardo Bras , Jens Axboe References: <20190801222417.14413-1-leonardo@linux.ibm.com> From: "Michael Kerrisk (man-pages)" Message-ID: Date: Fri, 13 Sep 2019 14:55:06 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190801222417.14413-1-leonardo@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-man-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org Hello Jens, Would you be willing to take a look at this man-pages bug report relating to vmsplice()? Thanks, Michael On 8/2/19 12:24 AM, Leonardo Bras wrote: > As explained in splice.2, SPLICE_F_MOVE became a no-op, and since it > is needed to use page gifting, it made SPLICE_F_GIFT a no-op too. > > I took a look in current code, and found no use of this flag: > When enabled, it sets PIPE_BUF_FLAG_GIFT,which is only checked in > user_page_pipe_buf_steal, which is only used on > user_page_pipe_buf_ops, as a .steal component. > > But, in the whole kernel code, there is no calling of a steal() > function, making me believe this flag is not used anymore. > > Signed-off-by: Leonardo Bras > --- > man2/vmsplice.2 | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/man2/vmsplice.2 b/man2/vmsplice.2 > index 17834607b..94fb86142 100644 > --- a/man2/vmsplice.2 > +++ b/man2/vmsplice.2 > @@ -123,6 +123,11 @@ if this flag is not specified, then a subsequent > .B SPLICE_F_MOVE > must copy the pages. > Data must also be properly page aligned, both in memory and length. > +Starting in Linux 2.6.21, it is a no-op, because the > +.B SPLICE_F_MOVE > +also became a no-op on > +.BR splice (2) > +. > .\" FIXME > .\" It looks like the page-alignment requirement went away with > .\" commit bd1a68b59c8e3bce45fb76632c64e1e063c3962d > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/