From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 27 Nov 2007 16:09:41 -0800 (PST) From: Christoph Lameter Subject: Re: [PATCH 1/1] mm: Prevent dereferencing non-allocated per_cpu variables In-Reply-To: <20071127154213.11970e63.akpm@linux-foundation.org> Message-ID: References: <20071127215052.090968000@sgi.com> <20071127215054.660250000@sgi.com> <20071127221628.GG24223@one.firstfloor.org> <20071127151241.038c146d.akpm@linux-foundation.org> <20071127152122.1d5fbce3.akpm@linux-foundation.org> <20071127154213.11970e63.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: andi@firstfloor.org, travis@sgi.com, ak@suse.de, pageexec@freemail.hu, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Tue, 27 Nov 2007, Andrew Morton wrote: > I don't recall anyone ever demonstrating that prefetch is useful in-kernel. vmstat: remove prefetch Remove the prefetch logic in order to avoid touching impossible per cpu areas. Signed-off-by: Christoph Lameter --- mm/vmstat.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) Index: linux-2.6/mm/vmstat.c =================================================================== --- linux-2.6.orig/mm/vmstat.c 2007-11-27 16:04:15.345713812 -0800 +++ linux-2.6/mm/vmstat.c 2007-11-27 16:07:00.552713192 -0800 @@ -21,21 +21,14 @@ EXPORT_PER_CPU_SYMBOL(vm_event_states); static void sum_vm_events(unsigned long *ret, cpumask_t *cpumask) { - int cpu = 0; + int cpu; int i; memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long)); - cpu = first_cpu(*cpumask); - while (cpu < NR_CPUS) { + for_each_cpu_mask(cpu, *cpumask) { struct vm_event_state *this = &per_cpu(vm_event_states, cpu); - cpu = next_cpu(cpu, *cpumask); - - if (cpu < NR_CPUS) - prefetch(&per_cpu(vm_event_states, cpu)); - - for (i = 0; i < NR_VM_EVENT_ITEMS; i++) ret[i] += this->event[i]; } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org