From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755045AbbKWR57 (ORCPT ); Mon, 23 Nov 2015 12:57:59 -0500 Received: from casper.infradead.org ([85.118.1.10]:59674 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754704AbbKWR56 (ORCPT ); Mon, 23 Nov 2015 12:57:58 -0500 Date: Mon, 23 Nov 2015 18:57:54 +0100 From: Peter Zijlstra To: Lianwei Wang Cc: linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, rjw@rjwysocki.net, mingo@redhat.com Subject: Re: [PATCH] sched: idle: move need_resched check after function rcu_idle_enter Message-ID: <20151123175754.GL17308@twins.programming.kicks-ass.net> References: <20151123130533.GY3816@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 On Mon, Nov 23, 2015 at 09:42:06AM -0800, Lianwei Wang wrote: > Issue was found on ARM/Qcom platform, but I think it is applicable to > other platforms as well. I add a BUG_ON after rcu_enter_idle to catch > it. The Qcom's cpuidle driver is not in mainline kernel yet. A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? And I suspect that your qualcom thing doesn't have TIF_POLLING_NRFLAG either, which would introduce another need_resched() test after the rcu_enter_idle() call.