From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932141AbWB1DRl (ORCPT ); Mon, 27 Feb 2006 22:17:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932148AbWB1DRl (ORCPT ); Mon, 27 Feb 2006 22:17:41 -0500 Received: from smtp.osdl.org ([65.172.181.4]:48303 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S932141AbWB1DRk (ORCPT ); Mon, 27 Feb 2006 22:17:40 -0500 Date: Mon, 27 Feb 2006 19:16:30 -0800 From: Andrew Morton To: "Rafael J. Wysocki" Cc: pavel@suse.cz, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH -mm 1/2] mm: make shrink_all_memory overflow-resistant Message-Id: <20060227191630.467846d7.akpm@osdl.org> In-Reply-To: <200602271928.22791.rjw@sisk.pl> References: <200602271926.20294.rjw@sisk.pl> <200602271928.22791.rjw@sisk.pl> 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 "Rafael J. Wysocki" wrote: > > Make shrink_all_memory() overflow-resistant. > As you've probably noticed, I'm moving toward making all the scalars which hold counts of pages in the VM toward unsigned long. For uniformity, and because there is a small risk that a huge machine with 4k pages could actually overflow a 32-bit counter. > Signed-off-by: Rafael J. Wysocki > --- > include/linux/swap.h | 2 +- > mm/vmscan.c | 9 +++++---- > 2 files changed, 6 insertions(+), 5 deletions(-) > > Index: linux-2.6.16-rc4-mm2/mm/vmscan.c > =================================================================== > --- linux-2.6.16-rc4-mm2.orig/mm/vmscan.c > +++ linux-2.6.16-rc4-mm2/mm/vmscan.c > @@ -1785,18 +1785,19 @@ void wakeup_kswapd(struct zone *zone, in > * Try to free `nr_pages' of memory, system-wide. Returns the number of freed > * pages. > */ > -int shrink_all_memory(unsigned long nr_pages) > +unsigned long shrink_all_memory(unsigned int nr_pages) So nr_pages should remain unsigned long. > + long long nr_to_free = nr_pages; As should nr_to_free. The actual bug is the (unsigned <= 0) thing. So how's about this? --- devel/include/linux/swap.h~vmscan-use-unsigned-longs-shrink_all_memory-fix 2006-02-27 19:13:30.000000000 -0800 +++ devel-akpm/include/linux/swap.h 2006-02-27 19:13:30.000000000 -0800 @@ -173,7 +173,7 @@ extern void swap_setup(void); /* linux/mm/vmscan.c */ extern unsigned long try_to_free_pages(struct zone **, gfp_t); -extern int shrink_all_memory(unsigned long nr_pages); +extern unsigned long shrink_all_memory(unsigned long nr_pages); extern int vm_swappiness; #ifdef CONFIG_NUMA --- devel/mm/vmscan.c~vmscan-use-unsigned-longs-shrink_all_memory-fix 2006-02-27 19:13:30.000000000 -0800 +++ devel-akpm/mm/vmscan.c 2006-02-27 19:13:30.000000000 -0800 @@ -1779,22 +1779,23 @@ void wakeup_kswapd(struct zone *zone, in * Try to free `nr_pages' of memory, system-wide. Returns the number of freed * pages. */ -int shrink_all_memory(unsigned long nr_pages) +unsigned long shrink_all_memory(unsigned long nr_pages) { pg_data_t *pgdat; unsigned long nr_to_free = nr_pages; - int ret = 0; + unsigned long ret = 0; struct reclaim_state reclaim_state = { .reclaimed_slab = 0, }; current->reclaim_state = &reclaim_state; for_each_pgdat(pgdat) { - int freed; + unsigned long freed; + freed = balance_pgdat(pgdat, nr_to_free, 0); ret += freed; nr_to_free -= freed; - if (nr_to_free <= 0) + if ((long)nr_to_free <= 0) break; } current->reclaim_state = NULL; _