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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 A49A0C04EBD for ; Tue, 16 Oct 2018 14:03:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 52690205C9 for ; Tue, 16 Oct 2018 14:03:35 +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="ILPRrYWA" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 52690205C9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727192AbeJPVyK (ORCPT ); Tue, 16 Oct 2018 17:54:10 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:39168 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727006AbeJPVyK (ORCPT ); Tue, 16 Oct 2018 17:54:10 -0400 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=3l3A6OygduF1nH1H5Cn5NFNHaqJ5qCd53v7SN/pL1IE=; b=ILPRrYWAcDt/ksW5HqydbOjtw w/3sMJ4lmbOx+exFDL6KMwMTmIzWxYXje+Qc6K3oisf3Inmcyu6+Ph6GV8lpfmK7bv6GTfR3lLdIp aMpg8fKLc8sUxzljS2LQVrHcPMsKPlEcAUbyduHmgsJXWp6YD11SxiHHjHds1nlExcUdye6dNsFv2 5fjshsMS8xwTYKc2l1z4CmmSp+quwn/k9CvQtDfytpKO70CAYOVleXXzifaUJCxDRKw4OOfGJ4aG7 SESaRX31cv5VsmdZOYns7INMpMxszCYGvBtnWtSG5t7spa2S2QBumDmcaVhn38AqrDITKwO3J+7AJ M04Lo1m0g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gCPwS-0004UA-Ul; Tue, 16 Oct 2018 14:03:25 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 9893F20295866; Tue, 16 Oct 2018 16:03:22 +0200 (CEST) Date: Tue, 16 Oct 2018 16:03:22 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: syzbot , Borislav Petkov , "H. Peter Anvin" , LKML , mingo@redhat.com, nstange@suse.de, syzkaller-bugs@googlegroups.com, Juri Lelli Subject: Re: INFO: rcu detected stall in do_idle Message-ID: <20181016140322.GB3121@hirez.programming.kicks-ass.net> References: <000000000000a4ee200578172fde@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 16, 2018 at 03:24:06PM +0200, Thomas Gleixner wrote: > It does reproduce here but with a kworker stall. Looking at the reproducer: > > *(uint32_t*)0x20000000 = 0; > *(uint32_t*)0x20000004 = 6; > *(uint64_t*)0x20000008 = 0; > *(uint32_t*)0x20000010 = 0; > *(uint32_t*)0x20000014 = 0; > *(uint64_t*)0x20000018 = 0x9917; > *(uint64_t*)0x20000020 = 0xffff; > *(uint64_t*)0x20000028 = 0; > syscall(__NR_sched_setattr, 0, 0x20000000, 0); > > which means: > > struct sched_attr { > .size = 0, > .policy = 6, > .flags = 0, > .nice = 0, > .priority = 0, > .deadline = 0x9917, > .runtime = 0xffff, > .period = 0, > } > > policy 6 is SCHED_DEADLINE > > That makes the thread hog the CPU and prevents all kind of stuff to run. > > Peter, is that expected behaviour? Sorta, just like FIFO-99 while(1);. Except we should be rejecting the above configuration, because of the rule: runtime <= deadline <= period Juri, where were we supposed to check that?