From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932832AbbLCJeN (ORCPT <rfc822;w@1wt.eu>);
	Thu, 3 Dec 2015 04:34:13 -0500
Received: from casper.infradead.org ([85.118.1.10]:52404 "EHLO
	casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1757678AbbLCJdz (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 3 Dec 2015 04:33:55 -0500
Date: Thu, 3 Dec 2015 10:33:50 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Tejun Heo <tj@kernel.org>
Cc: Ulrich Obergfell <uobergfe@redhat.com>, Ingo Molnar <mingo@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 1/2] watchdog: introduce touch_softlockup_watchdog_sched()
Message-ID: <20151203093350.GP17308@twins.programming.kicks-ass.net>
References: <20151203002810.GJ19878@mtj.duckdns.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20151203002810.GJ19878@mtj.duckdns.org>
User-Agent: Mutt/1.5.21 (2012-12-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Dec 02, 2015 at 07:28:10PM -0500, Tejun Heo wrote:
> Hello,
> 
> There haven't been too many workqueue stall bugs; however, good part
> of them have been pretty painful to track down because there's no
> lockup detection mechanism for workqueue and it isn't easy to tell
> what's going on with workqueues; furthermore, some requirements are
> tricky to get right - e.g. it's not too difficult to miss
> WQ_MEM_RECLAIM for a workqueue which runs a work item which is flushed
> by something which sits in the reclaim path.

have you considered something as simple as:

	WARN_ON(current->reclaim_state && !WQ_MEM_RECLAIM);

?