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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 154C4C4360F for ; Thu, 4 Apr 2019 16:34:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D0662206BA for ; Thu, 4 Apr 2019 16:33:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b="n9gqPJUE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729442AbfDDQd6 (ORCPT ); Thu, 4 Apr 2019 12:33:58 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:34185 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727339AbfDDQd6 (ORCPT ); Thu, 4 Apr 2019 12:33:58 -0400 Received: by mail-ed1-f66.google.com with SMTP id x14so2853742eds.1 for ; Thu, 04 Apr 2019 09:33:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=googlenew; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=2hndytGoUoqBgymO1uHWgt6ocOekMb3MD90dT3rk3MQ=; b=n9gqPJUEgZVRvbEY8FgzUu1/ntSYuK7gXNPSrcCIemP1+uUSwXbMJhfeS031NiSL9R Zj2D+IXmbWAZRsW+PnUMy4zxtR7fcqlOohbcGMUWmVZ40j1ngUfE2Lqhq/0S+i5jTSeQ STxKcxm36xeID3dnwl1+wlmV7Rh1GLjQ6Gr1tT/MINkED5LBLuycXGSFASHmwnYqZkFK 0hmEAf2DzHRi/n55RAZM0hezH69OagZI9BRumG/4owKVv0o4DD2lcdbugAwm5VmotfkW 3AdtnB41tj8CVaS5EYxg1t75xLQK5fUIJD1tXpdOjGF1gLrVuKLy0PikVV7HSNMr9kcF 9Fzw== 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=2hndytGoUoqBgymO1uHWgt6ocOekMb3MD90dT3rk3MQ=; b=lK4/Tl6ASA1shvTEfO846X0BL8hfBAjVVWYcrOgj/ANuRAiFnR6TBfk6m0pbXLXMTa 7Z2aShp9mIv1adLepfNb3CqDEALdjvOhQ41wHIpKYF9qmhDnnjdr5RHqyjsMold4NdHb WYvgmeeOs7rfT+vX3uTQO1HEV50YRm67SJZrzR3FLLY5EWdL0gC4pRh7zpoykUbOjnd6 naGei1F0FzoZ7CgDGUjTgY+kdqQ+46c8iIQtReojs2qR5IylZdjlNMVatoJJ3WAN/7vI 6nKtrhPlJ7e9OGMOIGD7BPZeC/WjpxwuWJz52C7WRRty0VFuq218arWqqF1roXufJ04v YHeg== X-Gm-Message-State: APjAAAUt7wR3BQd8BvFVWCDP2Iq1rIMtNrHuAOmF863/ZsETxIO+qVur yKMfcezXkjHa9HNcsjppAcYKlg== X-Google-Smtp-Source: APXvYqy14bFpFFt+392XPIYr1mdvfkPyTgLw1PaezgBQ+9km//noeFBUnjQlmaWYwqJRMMGmEKn4Xg== X-Received: by 2002:a17:906:1584:: with SMTP id k4mr4179829ejd.226.1554395636245; Thu, 04 Apr 2019 09:33:56 -0700 (PDT) Received: from [10.83.36.153] ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id b3sm3677993eje.3.2019.04.04.09.33.54 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Thu, 04 Apr 2019 09:33:55 -0700 (PDT) Subject: Re: [RFC 1/4] net/ipv4/fib: Remove run-time check in tnode_alloc() To: Alexander Duyck , Dmitry Safonov <0x7f454c46@gmail.com>, linux-kernel@vger.kernel.org Cc: Alexey Kuznetsov , David Ahern , "David S. Miller" , Eric Dumazet , Hideaki YOSHIFUJI , Ido Schimmel , netdev@vger.kernel.org References: <20190326153026.24493-1-dima@arista.com> <20190326153026.24493-2-dima@arista.com> <5beb631cf0dcc03d5afad3a29671677bdbc7b931.camel@linux.intel.com> From: Dmitry Safonov Message-ID: <992772b9-3565-c616-614b-303fcc078978@arista.com> Date: Thu, 4 Apr 2019 17:33:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.3 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/1/19 6:50 PM, Alexander Duyck wrote: > On Mon, 2019-04-01 at 16:55 +0100, Dmitry Safonov wrote: > Actually now that I think about it TNODE_VMALLOC_MAX is likely much > less than 31. The logic that we have to be concerned with is: > size = TNODE_SIZE(1ul << bits); > > If size is a 32b value, and the size of a pointer is 4 bytes, then our > upper limit is roughly ilog2((4G - 28) / 4), which comes out to 29. > What we are trying to avoid is overflowing the size variable, not > actually limiting the vmalloc itself. Oh yes, I see - managed to forget that size can also overflow inside TNODE_SIZE(). >> So, I wanted to remove run-time check here on x86_64.. >> I could do it by adding !CONFIG_64BIT around the check. > > I have no problem with that. All I am suggesting is that if at all > possible we should use TNODE_VMALLOC_MAX instead of BITS_PER_LONG. Yeah, will rework this part. Thanks, Dmitry