From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756317AbaCYR4m (ORCPT ); Tue, 25 Mar 2014 13:56:42 -0400 Received: from cantor2.suse.de ([195.135.220.15]:58474 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755320AbaCYR4j (ORCPT ); Tue, 25 Mar 2014 13:56:39 -0400 Date: Tue, 25 Mar 2014 10:56:34 -0700 From: Michal Hocko To: Christoph Lameter Cc: Sasha Levin , Pekka Enberg , Matt Mackall , "linux-mm@kvack.org" , LKML Subject: Re: mm: slub: gpf in deactivate_slab Message-ID: <20140325175634.GC7519@dhcp22.suse.cz> References: <53208A87.2040907@oracle.com> <5331A6C3.2000303@oracle.com> <20140325165247.GA7519@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 25-03-14 12:06:36, Christoph Lameter wrote: > On Tue, 25 Mar 2014, Michal Hocko wrote: > > > You are right. The function even does VM_BUG_ON(!irqs_disabled())... > > Unfortunatelly we do not seem to have an _irq alternative of the bit > > spinlock. > > Not sure what to do about it. Christoph? > > > > Btw. it seems to go way back to 3.1 (1d07171c5e58e). > > Well there is a preempt_enable() (bit_spin_lock) and a preempt_disable() > bit_spin_unlock() within a piece of code where irqs are disabled. > > Is that a problem? Has been there for a long time. It is because preempt_enable calls __preempt_schedule when the preempt count drops down to 0. You would need to call preempt_disable before you disable interrupts or use an irq safe bit spin unlock which doesn't enabled preemption unconditionally. -- Michal Hocko SUSE Labs