From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031094AbXDYP3a (ORCPT ); Wed, 25 Apr 2007 11:29:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1031097AbXDYP3a (ORCPT ); Wed, 25 Apr 2007 11:29:30 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:49364 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1031094AbXDYP33 (ORCPT ); Wed, 25 Apr 2007 11:29:29 -0400 Date: Wed, 25 Apr 2007 08:29:28 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Hugh Dickins cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH -mm] slub: update cpu after new_slab() In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 25 Apr 2007, Hugh Dickins wrote: > SLUB gave me a NULL pointer dereference in slab_alloc(), in the > slab_lock(page) of its "Current cpuslab is acceptable" block: cpu > 1 had been looking at cpu_slab[2], which then went NULL beneath it. > Since new_slab() may reenable interrupts and sleep (when __GFP_WAIT), > we may get rescheduled on a different cpu: so need to reevaluate it. Right. local_irq_save does not switch off preemption as I thought. Acked-by: Christoph Lameter