From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752337AbaHDMZm (ORCPT ); Mon, 4 Aug 2014 08:25:42 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:47328 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751033AbaHDMZl (ORCPT ); Mon, 4 Aug 2014 08:25:41 -0400 Date: Mon, 4 Aug 2014 14:25:15 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Lai Jiangshan , linux-kernel@vger.kernel.org, mingo@kernel.org, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com Subject: Re: [PATCH v3 tip/core/rcu 1/9] rcu: Add call_rcu_tasks() Message-ID: <20140804122515.GR19379@twins.programming.kicks-ass.net> References: <20140731215445.GA21933@linux.vnet.ibm.com> <1406843709-23396-1-git-send-email-paulmck@linux.vnet.ibm.com> <53DEE1CD.4000705@cn.fujitsu.com> <20140804074620.GH9918@twins.programming.kicks-ass.net> <53DF41ED.2020508@cn.fujitsu.com> <20140804115043.GA31903@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="RMnrteHbcZy6jON6" Content-Disposition: inline In-Reply-To: <20140804115043.GA31903@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --RMnrteHbcZy6jON6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Aug 04, 2014 at 04:50:44AM -0700, Paul E. McKenney wrote: > OK, I will bite... >=20 > What kinds of tasks are on a runqueue, but neither ->on_cpu nor > PREEMPT_ACTIVE? Userspace tasks, they don't necessarily get PREEMPT_ACTIVE when preempted. Now obviously you're not _that_ interested in userspace tasks for this, so that might be ok. But the main point was, you cannot use ->on_cpu or PREEMPT_ACTIVE without holding rq->lock. --RMnrteHbcZy6jON6 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJT33urAAoJEHZH4aRLwOS6WEAQALQaqEOWCoK2lAcUtGNrwmUX sx6Tjn1GFRfCmBC7D0B9mJn19ehIdFcx1+ZrxcHmsRC4r0eA0XaVCjsnXeEJaYwu FJFO3x539C7NoDtDOau3h8j/jZDpOxSp4VCGK/8vVzbyaAy25eeteFsMwBJiRyks AbR+8GoXVOBdMVp7jfqEOCshUf4xtkxbPKW0AEKSJMARghCkULqDRdLgpSx7XyHf A3nzqQrxdc2Q/ct1TJ0mZF2FPyGDW6v7nYLVov+ZOMOipt2r0/MYVqrzCo0RMUJ4 Nld7HRUjMIItDJ3U12FehxEucHYp7Addx+6qSYHi/yF6w0K1EEQGKPvi+yem6EKb mdE1fC7h5isV4S7f7RkmzOaDbt1V3EwUn5mS1W/S3T9TISvKAqourzfIhii5mJLl cwZ7gRja3QTXUy8+BE/xu//oxyESt+h2eUKu61nFzP7u2SpdoaTWSPkoyxurMxd5 TTn8kczNy1whVNI0l9mullpDkm3tg8JO6K2OxZSVMr9gdqp4oEqjEgwx9/ecEZy/ 8WG1hbX+/dsHcCxxVmQCT7gPUsZoZjuzXTqTb6z1Km3oBoiTklRiNHp5nfHcXI9z aK3XWAqlKuYM+PPNqp+AhlGbsrICfdy8b1blSAh78bK+pyqdpQhz1AtUf9Y/H/Fv h753YMjWnI7bLIZyGlsu =woGM -----END PGP SIGNATURE----- --RMnrteHbcZy6jON6--