From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933259Ab0JZN0f (ORCPT ); Tue, 26 Oct 2010 09:26:35 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:57670 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932101Ab0JZN0e (ORCPT ); Tue, 26 Oct 2010 09:26:34 -0400 Date: Tue, 26 Oct 2010 15:25:48 +0200 From: Ingo Molnar To: Tejun Heo Cc: torvalds@osdl.org, Alexander van Heukelum , David Howells , akpm@linux-foundation.org, linux-am33-list@redhat.com, linux-kernel@vger.kernel.org, Akira Takeuchi , Mark Salter Subject: Re: [PATCH] x86, percpu: revert commit fe8e0c25 Message-ID: <20101026132548.GA14666@elte.hu> References: <4CC69B22.2050708@kernel.org> <20101025224111.7798.38960.stgit@warthog.procyon.org.uk> <12101.1288088542@redhat.com> <4CC6C62F.1000804@kernel.org> <4CC6C941.2080003@kernel.org> <4CC6CD4D.3010501@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4CC6CD4D.3010501@kernel.org> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Tejun Heo wrote: > Commit fe8e0c25 (x86, 32-bit: Align percpu area and irq stacks to THREAD_SIZE) > aligned PERCPU section to THREAD_SIZE which can be larger than PAGE_SIZE, > introduced DEFINE_PER_CPU_MULTIPAGE_ALIGNED() and used it to make irq stacks > aligned to THREAD_SIZE on x86_32. > > This won't work. The PERCPU output section is used as the template to prepare the > percpu area and the actual percpu area is _alwasy_ aligned to PAGE_SIZE whether > the source area is aligned to larger size or not. The problem is, this will reintroduce a nasty boot crash which commit fe8e0c25 fixed. Do you say that fe8e0c25 didnt have the alignment effect? Ingo