From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932183AbeDWQ5y (ORCPT ); Mon, 23 Apr 2018 12:57:54 -0400 Received: from fllnx209.ext.ti.com ([198.47.19.16]:25593 "EHLO fllnx209.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932079AbeDWQ5x (ORCPT ); Mon, 23 Apr 2018 12:57:53 -0400 Subject: Re: [ANNOUNCE] v4.14.29-rt25 To: Sebastian Andrzej Siewior CC: Thomas Gleixner , LKML , linux-rt-users , Steven Rostedt References: <20180325101204.ibuvdpnusv3vutyc@linutronix.de> <20180420171116.w2hxytgzvp4jgpyl@linutronix.de> From: Grygorii Strashko Message-ID: <764d0abc-7e88-a696-17a0-0bf807148d5b@ti.com> Date: Mon, 23 Apr 2018 11:57:39 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180420171116.w2hxytgzvp4jgpyl@linutronix.de> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/20/2018 12:11 PM, Sebastian Andrzej Siewior wrote: > On 2018-03-27 13:01:07 [-0500], Grygorii Strashko wrote: >> Hi Sebastian, > Hi Grygorii, > >> I've took this RT version and applied "[RT] kernel/time/posix-timer: avoid schedule() >> while holding the RCU lock" [1] on top. Then I run below tests: > … >> no stall or crashes were observed, but I've caught two "rcu_note_context_switch()" warnings > > the warning is unrelated to the patch I posted. This should mute it: > > Subject: [PATCH RT] rtmutex: annotate sleeping lock context > > The RCU code complains on schedule() within a rcu_readlock() section. > The valid scenario on -RT is if a sleeping is held. In order to suppress > the warning the mirgrate_disable counter was used to identify the > invocation of schedule() due to lock contention. > > Grygorii Strashko report that during CPU hotplug we might see the > warning via > rt_spin_lock() -> migrate_disable() -> pin_current_cpu() -> __read_rt_lock() > > because the counter is not yet set. > It is also possible to trigger the warning from cpu_chill() > (seen on a kblockd_mod_delayed_work_on() caller). > > To address this RCU warning I annotate the sleeping lock context. The > counter is incremented before migrate_disable() so the warning Grygorii > should not trigger anymore. Additionally I use that counter in > cpu_chill() to avoid the RCU warning from there. Sry, but I can't apply it. What's you base? > > Reported-by: Grygorii Strashko > Signed-off-by: Sebastian Andrzej Siewior > --- -- regards, -grygorii