From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66ADBC4363A for ; Tue, 27 Oct 2020 09:00:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F321622264 for ; Tue, 27 Oct 2020 09:00:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="2d+JeKFm"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Al+1deZf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2895236AbgJ0JAY (ORCPT ); Tue, 27 Oct 2020 05:00:24 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:45734 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406413AbgJ0JAX (ORCPT ); Tue, 27 Oct 2020 05:00:23 -0400 Date: Tue, 27 Oct 2020 10:00:19 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1603789221; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=FhFXv1BRUKRnsS9ExGJBDAdxNamEG0cPUveqq9dD0aQ=; b=2d+JeKFmrjaKpZBSJEHmG2kCauwy3OgCERQ1hpndwsYke2PmzCfR4pPbwcH+IeJj7B5bE8 Hbbo5sODvHRyaqtMM4be11LjmOzNN+Jou/slTP8Sb5EUz3vAL4Qfb1ZRcPVfFKMBqxZX1Z haLHmB1KEMQBpOD2mxHAoj3UKKYZsUD/s9hEZwvAbk4Wkm2NLAopZciYCeaYYI3KhfhP8T 9Vj+fVYsDKGKjYtTpWWLvp63PyvMMdXzblors7Scx6bnbkouFA+wjLSD9khZAW6CU98DVZ Ulw+O79TmwzjyHIq4kwCGqq0u1sBeQuZC1EUwxKoe1Nptcv++eeQdn8FITPmWw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1603789221; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=FhFXv1BRUKRnsS9ExGJBDAdxNamEG0cPUveqq9dD0aQ=; b=Al+1deZf1TJ9yM8BZB1nWmTwGerGXKo3tMU81KhDWg+V/rfJ0VkuEmVB49EHuG4s6eDdmj rEuAPwBb+6f2k1Bw== From: Sebastian Andrzej Siewior To: Mike Galbraith Cc: Hillf Danton , Thomas Gleixner , LKML , linux-rt-users , Steven Rostedt , Ben Skeggs Subject: Re: kvm+nouveau induced lockdep gripe Message-ID: <20201027090019.3vteojm43ljqqe33@linutronix.de> References: <20201021125324.ualpvrxvzyie6d7d@linutronix.de> <20201023090108.5lunh4vqfpkllmap@linutronix.de> <20201024022236.19608-1-hdanton@sina.com> <20201024050000.8104-1-hdanton@sina.com> <20201026173107.quylcy6fgjvrqat6@linutronix.de> <431e81699f2310eabfe5af0a3de400ab99d9323b.camel@gmx.de> <20201026195308.wsbk7xy57wuzfbao@linutronix.de> <0dfae65db2f0d3ef603c1db34f37cee63f7f41f4.camel@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <0dfae65db2f0d3ef603c1db34f37cee63f7f41f4.camel@gmx.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-10-27 07:03:38 [+0100], Mike Galbraith wrote: > On Mon, 2020-10-26 at 20:53 +0100, Sebastian Andrzej Siewior wrote: > > > > Could you try this, please? > > Nogo, first call of sched_setscheduler() is via kthread_create(). I > confirmed that nuking that (gratuitous user foot saving override) call > on top of moving sched_set_fifo() does shut it up, but that won't fly. mkay. but this then, too. Let me try if I can figure out when this broke. diff --git a/kernel/kthread.c b/kernel/kthread.c index 3edaa380dc7b4..64d6afb127239 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -244,6 +244,7 @@ EXPORT_SYMBOL_GPL(kthread_parkme); static int kthread(void *_create) { /* Copy data: it's on kthread's stack */ + static const struct sched_param param = { .sched_priority = 0 }; struct kthread_create_info *create = _create; int (*threadfn)(void *data) = create->threadfn; void *data = create->data; @@ -273,6 +274,13 @@ static int kthread(void *_create) init_completion(&self->parked); current->vfork_done = &self->exited; + /* + * root may have changed our (kthreadd's) priority or CPU mask. + * The kernel thread should not inherit these properties. + */ + sched_setscheduler_nocheck(current, SCHED_NORMAL, ¶m); + set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_KTHREAD)); + /* OK, tell user we're spawned, wait for stop or wakeup */ __set_current_state(TASK_UNINTERRUPTIBLE); create->result = current; @@ -370,7 +378,6 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), } task = create->result; if (!IS_ERR(task)) { - static const struct sched_param param = { .sched_priority = 0 }; char name[TASK_COMM_LEN]; /* @@ -379,13 +386,6 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), */ vsnprintf(name, sizeof(name), namefmt, args); set_task_comm(task, name); - /* - * root may have changed our (kthreadd's) priority or CPU mask. - * The kernel thread should not inherit these properties. - */ - sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); - set_cpus_allowed_ptr(task, - housekeeping_cpumask(HK_FLAG_KTHREAD)); } kfree(create); return task; Sebastian