Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755307AbaFKEKd (ORCPT ); Wed, 11 Jun 2014 00:10:33 -0400 Received: from mail-we0-f173.google.com ([74.125.82.173]:34287 "EHLO mail-we0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750882AbaFKEKI (ORCPT ); Wed, 11 Jun 2014 00:10:08 -0400 Message-ID: <1402459804.5195.19.camel@marge.simpson.net> Subject: Re: [RFC PATCH V2] rt/aio: fix rcu garbage collection might_sleep() splat From: Mike Galbraith To: Benjamin LaHaise Cc: Kent Overstreet , Lai Jiangshan , RT , LKML , Sebastian Andrzej Siewior , Steven Rostedt , Thomas Gleixner , "Paul E. McKenney" Date: Wed, 11 Jun 2014 06:10:04 +0200 In-Reply-To: <20140610175001.GF27015@kvack.org> References: <1402216538.31630.7.camel@marge.simpson.net> <5395172E.4010007@cn.fujitsu.com> <1402372048.5124.20.camel@marge.simpson.net> <20140610175001.GF27015@kvack.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 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, 2014-06-10 at 13:50 -0400, Benjamin LaHaise wrote: > On Tue, Jun 10, 2014 at 05:47:28AM +0200, Mike Galbraith wrote: > > On Mon, 2014-06-09 at 10:08 +0800, Lai Jiangshan wrote: > > > Hi, rt-people > > > > > > I don't think it is the correct direction. > > > Softirq (including local_bh_disable()) in RT kernel should be preemptible. > > > > How about the below then? > > > > I was sorely tempted to post a tiny variant that dropped taking ctx_lock > > in free_ioctx_users() entirely, as someone diddling with no reference > > didn't make sense. Cc Ben, he would know. > > That should be okay... Let's ask Kent to chime in on whether this looks > safe to him on the percpu ref front as well, since he's the one who wrote > this code. Looking at the gizzard of our in-tree user of kiocb_set_cancel_fn() (gadget), cancel() leads to dequeue() methods, which take other sleeping locks, so tiniest variant is not an option, patchlet stands. -Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/