Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750863AbVKJNbF (ORCPT ); Thu, 10 Nov 2005 08:31:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750867AbVKJNbF (ORCPT ); Thu, 10 Nov 2005 08:31:05 -0500 Received: from gold.veritas.com ([143.127.12.110]:11428 "EHLO gold.veritas.com") by vger.kernel.org with ESMTP id S1750863AbVKJNbD (ORCPT ); Thu, 10 Nov 2005 08:31:03 -0500 Date: Thu, 10 Nov 2005 13:29:49 +0000 (GMT) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: Andrew Morton cc: mingo@elte.hu, linux-kernel@vger.kernel.org, torvalds@osdl.org Subject: Re: [PATCH 01/15] mm: poison struct page for ptlock In-Reply-To: <20051110045144.40751a42.akpm@osdl.org> Message-ID: References: <20051109181022.71c347d4.akpm@osdl.org> <20051109185645.39329151.akpm@osdl.org> <20051110120624.GB32672@elte.hu> <20051110045144.40751a42.akpm@osdl.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 10 Nov 2005 13:31:02.0877 (UTC) FILETIME=[FEC400D0:01C5E5FA] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1092 Lines: 27 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. There is just one case where it would, so in that case split ptlock is disabled by mm/Kconfig's # PA-RISC 7xxx's debug spinlock_t is too large for 32-bit struct page. default "4096" if PARISC && DEBUG_SPINLOCK && !PA20 Of course, someone may extend spinlock debugging info tomorrow; but when they do, presumably they'll try it out, and hit the BUILD_BUG_ON. They'll then probably want to extend the suppression in mm/Kconfig. Hugh - 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/