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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,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 8ECD1C2BA19 for ; Thu, 23 Apr 2020 09:26:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 68AE121569 for ; Thu, 23 Apr 2020 09:26:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="EGmDUza5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726914AbgDWJ0f (ORCPT ); Thu, 23 Apr 2020 05:26:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53108 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725863AbgDWJ0e (ORCPT ); Thu, 23 Apr 2020 05:26:34 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD80BC03C1AF for ; Thu, 23 Apr 2020 02:26:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=AhqqTWP07O6E8+pNvQs5WZMEOhvWks1ANvCjRq43y8s=; b=EGmDUza5qNYoWfeduybh4XZoUS CQVfQ0XuMxATSC4TL9wEMHCSphDdgmMVAvVpqBBTnKNEb7V0aZ9UESlSEC2jAbvjaheY3uTCWIN8Q pbNEZu/hnl/bLNuqTrVnlRRqjRembY0SDAmq1c6HlMCkVE7/ghBDNNYgXnI+PpXLA2uy4g0rhEKzQ TR6ryKn3DnpGNsxYnPe9e8HaoYTd2/oH4UfiUt/wmnamb1/G1/s1bp5KYjF/kppa45IX1R+EBbY+6 o/nQAkM8L1sSvuiPWv9DSl2CUz9XNfQ/GYFKBIE1un1jsIkMSjvX4B8p6PPbPWucSfKM0RxstWPer FznTrTpA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jRY7i-00029C-Ap; Thu, 23 Apr 2020 09:26:22 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 93577306099; Thu, 23 Apr 2020 11:26:20 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7A5F323D19EEE; Thu, 23 Apr 2020 11:26:20 +0200 (CEST) Date: Thu, 23 Apr 2020 11:26:20 +0200 From: Peter Zijlstra To: Hillf Danton Cc: Steven Rostedt , Mike Galbraith , lkml , Ingo Molnar Subject: Re: [PATCH] sched: make p->prio independent of p->mm Message-ID: <20200423092620.GR20730@hirez.programming.kicks-ass.net> References: <20200423040128.6120-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200423040128.6120-1-hdanton@sina.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 23, 2020 at 12:01:28PM +0800, Hillf Danton wrote: > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -4796,13 +4796,19 @@ recheck: > return -EINVAL; > > /* > - * Valid priorities for SCHED_FIFO and SCHED_RR are > - * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, > - * SCHED_BATCH and SCHED_IDLE is 0. > + * The MAX_USER_RT_PRIO value allows the actual maximum > + * RT priority to be separate from the value exported to > + * user-space. This allows kernel threads to set their > + * priority to a value higher than any user task. > */ > - if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) || > - (!p->mm && attr->sched_priority > MAX_RT_PRIO-1)) > - return -EINVAL; > + if (p->flags & PF_KTHREAD) { > + if (attr->sched_priority > MAX_RT_PRIO - 1) > + return -EINVAL; > + } else { > + if (attr->sched_priority > MAX_USER_RT_PRIO - 1) > + return -EINVAL; > + } > + Arguably we can do away with the check entirely, MAX_RT_PRIO == MAX_USER_RT_PRIO.