Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750702AbVJWVtv (ORCPT ); Sun, 23 Oct 2005 17:49:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750704AbVJWVtv (ORCPT ); Sun, 23 Oct 2005 17:49:51 -0400 Received: from smtp.osdl.org ([65.172.181.4]:63145 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1750702AbVJWVtu (ORCPT ); Sun, 23 Oct 2005 17:49:50 -0400 Date: Sun, 23 Oct 2005 14:49:00 -0700 From: Andrew Morton To: Hugh Dickins Cc: clameter@sgi.com, rmk@arm.linux.org.uk, matthew@wil.cx, jdike@addtoit.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 7/9] mm: split page table lock Message-Id: <20051023144900.4a23704d.akpm@osdl.org> In-Reply-To: References: 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: 1224 Lines: 30 I did the make-it-a-union thing. Seems OK. Hugh Dickins wrote: > > +#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS > +/* > + * We tuck a spinlock to guard each pagetable page into its struct page, > + * at page->private, with BUILD_BUG_ON to make sure that this will not > + * overflow into the next struct page (as it might with DEBUG_SPINLOCK). > + * When freeing, reset page->mapping so free_pages_check won't complain. > + */ > +#define __pte_lockptr(page) ((spinlock_t *)&((page)->private)) > +#define pte_lock_init(_page) do { \ > + BUILD_BUG_ON((size_t)(__pte_lockptr((struct page *)0) + 1) > \ > + sizeof(struct page)); \ > + spin_lock_init(__pte_lockptr(_page)); \ > +} while (0) > +#define pte_lock_deinit(page) ((page)->mapping = NULL) > +#define pte_lockptr(mm, pmd) ({(void)(mm); __pte_lockptr(pmd_page(*(pmd)));}) > +#else Why does pte_lock_deinit() zap ->mapping? That doesn't seem to have anything to do with anything? - 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/