Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751204AbVKJTuJ (ORCPT ); Thu, 10 Nov 2005 14:50:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751212AbVKJTuJ (ORCPT ); Thu, 10 Nov 2005 14:50:09 -0500 Received: from smtp.osdl.org ([65.172.181.4]:3036 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1751204AbVKJTuH (ORCPT ); Thu, 10 Nov 2005 14:50:07 -0500 Date: Thu, 10 Nov 2005 11:49:50 -0800 From: Andrew Morton To: Hugh Dickins Cc: mingo@elte.hu, linux-kernel@vger.kernel.org, torvalds@osdl.org Subject: Re: [PATCH 01/15] mm: poison struct page for ptlock Message-Id: <20051110114950.03a5946b.akpm@osdl.org> In-Reply-To: References: <20051109181022.71c347d4.akpm@osdl.org> <20051109185645.39329151.akpm@osdl.org> <20051110120624.GB32672@elte.hu> <20051110045144.40751a42.akpm@osdl.org> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1021 Lines: 28 Hugh Dickins wrote: > > On Thu, 10 Nov 2005, Andrew Morton wrote: > > Hugh Dickins wrote: > > > On Thu, 10 Nov 2005, Ingo Molnar wrote: > > > > > > > > yuck. What is the real problem btw? AFAICS there's enough space for a > > > > 2-word spinlock in struct page for pagetables. > > > > > > Yes. There is no real problem. But my patch offends good taste. > > > > Isn't it going to overrun page.lru with CONFIG_DEBUG_SPINLOCK? > > No. !no, methinks. On 32-bit architectures with CONFIG_PREEMPT, CONFIG_DEBUG_SPINLOCK, CONFIG_NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS we have a 32-byte page, a 20-byte spinlock and offsetof(page, private) == 12. IOW we're assuming that no 32-bit architectures will obtain pagetables from slab? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/