From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757499Ab2IYUNZ (ORCPT ); Tue, 25 Sep 2012 16:13:25 -0400 Received: from mail-ee0-f46.google.com ([74.125.83.46]:34455 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755283Ab2IYUNU (ORCPT ); Tue, 25 Sep 2012 16:13:20 -0400 Message-ID: <1348603996.12068.19.camel@maxim-laptop> Subject: Re: [PATCH v2 memstick: support for legacy sony memsticks From: Maxim Levitsky To: Tejun Heo Cc: Andrew Morton , Alex Dubov , linux-kernel@vger.kernel.org Date: Tue, 25 Sep 2012 22:13:16 +0200 In-Reply-To: <20120925194017.GK16296@google.com> References: <1348562326-10462-1-git-send-email-maximlevitsky@gmail.com> <20120925180235.GC16296@google.com> <1348601679.12068.17.camel@maxim-laptop> <20120925194017.GK16296@google.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2012-09-25 at 12:40 -0700, Tejun Heo wrote: > On Tue, Sep 25, 2012 at 09:34:39PM +0200, Maxim Levitsky wrote: > > But this just adds the WQ_UNBOUND. Dunno, without lock I had several > > crashes, that for high level of confidence caused by by parallel > > execution of work items. Once I added this mutex, I couldnt reproduce > > these. > > Yes the combination of WQ_UNBOUND and max_active==1 guarantees > strictly ordered one-by-one execution. > > > I had the __blk_end_request fail with NULL msb->req. I can't see how > > that can happen if work queue isn't executed in parallel. > > (and then the I didn't even had by mistake the code that sets it to NULL > > in msb_stop, so I really fail to see how that could happen due internal > > bug in my code. > > If you're seeing parallel execution w/ ordered workqueue, it is a > critical bug which would make the kernel crash left and right. Please > try alloc_ordered_workqueue() and if you still see parallel execution, > please report. I will test this very soon. Good to know, I am pretty sure, it will work. > > Thanks. > -- Best regards, Maxim Levitsky