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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 5D3FCC43381 for ; Wed, 20 Feb 2019 16:35:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 300FC2147C for ; Wed, 20 Feb 2019 16:35:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="RDOv2W9g" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726551AbfBTQfI (ORCPT ); Wed, 20 Feb 2019 11:35:08 -0500 Received: from mail-pl1-f173.google.com ([209.85.214.173]:37700 "EHLO mail-pl1-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725895AbfBTQfH (ORCPT ); Wed, 20 Feb 2019 11:35:07 -0500 Received: by mail-pl1-f173.google.com with SMTP id q3so5094180pll.4 for ; Wed, 20 Feb 2019 08:35:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=/xmq/6srY+HNgq1dzzKU27a1R87JJ0kF2Y0peDaC3cg=; b=RDOv2W9gaQ5XiFcT8IukcPVpDpHn+PMC9nmqolj85QlqbmR/se5U8GDd0ZsdpqwbSp +VVW9dRUWJVNTI0SpUybkRCQvCG+8aRyq7Q8qAUks7iK2Q7UKtf0vKxaxZ0NzXSXs/xp 7mc9aHRKSeubpwANWrE/6Qn9W+B2IMZKxOxYRcBQC73ZVwoAiKt/4slFu5DNcAXjy5k/ qxpkwoZ0uen4K25qy8ZSMeMUa93U863zbY8AysAIuA2ns6vmmu2dX0v7YOpESc6Fd8pI bbzTIqAmv+C4I5d1/nTFN4NzUWDShUppVordbQOfW3ZxI3Uun1lZZ7Rht3Qfpa8h61+f tBpw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=/xmq/6srY+HNgq1dzzKU27a1R87JJ0kF2Y0peDaC3cg=; b=H8U3AvsBVj0Cknz3a5K003f3PRR8QzyYELV5X1J38GAHPttO1gV2tp1jK6tik0yOWM 7Ey1jnRHODjxThibkSl4RexdCNn1EXv/XhX73KbLmkQAPWguFxTNN4fMAsnMvRe6q7b8 2a+t+cMHjwE1I2thQ0sLaz5fzuCZf4M290CJJ9W/zW6N5BCuSwxlcJ9MDy/re/ubaPGE PW14lsNw5j8CVoRzY6mE2OGu9JXiJhzl/M52N1kYO1UZ5AjbuYH3enYuTcqCjf7JE+KI Ac/MejD5OcwGpBnR0FnraplqcaCLIVI0Z/aJPTqOcbhQxkelk9DpNhV5pqD/QNEHjpv8 0utQ== X-Gm-Message-State: AHQUAuZYy15edAPLPyVCj7WgAPd5il4ZNcXliGGyFzx0z2cu4fudLxRU 8jQYdX8isRYy5ITPmTPKz3wTAHiD X-Google-Smtp-Source: AHgI3IY8EBRUWOEnawG0P+bXy9wrp7s1imBTksYNQz2qJyWmnfkQaG9FyiHkb62C+mOoI2GkdG7krQ== X-Received: by 2002:a17:902:aa8d:: with SMTP id d13mr37592144plr.293.1550680506692; Wed, 20 Feb 2019 08:35:06 -0800 (PST) Received: from ?IPv6:2620:15c:2c1:200:55c7:81e6:c7d8:94b? ([2620:15c:2c1:200:55c7:81e6:c7d8:94b]) by smtp.gmail.com with ESMTPSA id 20sm14252753pgr.80.2019.02.20.08.35.05 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Feb 2019 08:35:05 -0800 (PST) Subject: Re: skb_can_coalesce() merges tcp frags with XFS-related slab objects To: Vasily Averin , Eric Dumazet , "David S. Miller" Cc: Linux Kernel Network Developers , Ilya Dryomov References: <2dc88af7-3d29-58e1-00e0-127d1f798c28@gmail.com> From: Eric Dumazet Message-ID: Date: Wed, 20 Feb 2019 08:35:05 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 02/20/2019 08:19 AM, Vasily Averin wrote: > Thank you for explanation, > though this happen in real life and triggers BUG_ON only if receiving side is located on the same host. > Is it probably makes sense to add WARN_ON into skb_can_coalesce to detect such cases? Yes, but please do it only in the sendpage() path, or only in CONFIG_DEBUG_PAGEALLOC / CONFIG_DEBUG_VM cases. tcp_sendmsg() uses a per task page (look at sk_page_frag()), and it seems strange to recheck what we already know (it is a page not backed/used by SLAB)