From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751372AbVHVWf4 (ORCPT ); Mon, 22 Aug 2005 18:35:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751474AbVHVWeW (ORCPT ); Mon, 22 Aug 2005 18:34:22 -0400 Received: from zeus1.kernel.org ([204.152.191.4]:46218 "EHLO zeus1.kernel.org") by vger.kernel.org with ESMTP id S1751469AbVHVWeU (ORCPT ); Mon, 22 Aug 2005 18:34:20 -0400 From: Denis Vlasenko To: Chris Wright , linux-kernel@vger.kernel.org, stable@kernel.org Subject: Re: [patch 8/8] [PATCH] Module per-cpu alignment cannot always be met Date: Mon, 22 Aug 2005 09:58:17 +0300 User-Agent: KMail/1.5.4 Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , "Randy.Dunlap" , Chuck Wolber , torvalds@osdl.org, akpm@osdl.org, alan@lxorguk.ukuu.org.uk, rusty@rustcorp.com.au, Daniel Drake , Chris Wright References: <20050811225445.404816000@localhost.localdomain> <20050811225649.386948000@localhost.localdomain> In-Reply-To: <20050811225649.386948000@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="koi8-r" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200508220958.17800.vda@ilport.com.ua> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Friday 12 August 2005 01:54, Chris Wright wrote: > -stable review patch. If anyone has any objections, please let us know. > ------------------ > > The module code assumes noone will ever ask for a per-cpu area more than > SMP_CACHE_BYTES aligned. However, as these cases show, gcc asks sometimes > asks for 32-byte alignment for the per-cpu section on a module, and if > CONFIG_X86_L1_CACHE_SHIFT is 4, we hit that BUG_ON(). This is obviously an > unusual combination, as there have been few reports, but better to warn > than die. gcc gets increasingly sadistic about alignment: "char global_var[] = "larger than 32 bytes"; uses silly amounts of alignment even with -Os" http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22158 Please, everybody who thinks that _32_ _byte_ alignment is outright silly, add your comments to this bugzilla entry. -- vda