From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4C361196C67 for ; Wed, 2 Oct 2024 08:49:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727858983; cv=none; b=l4KJuNUQ7CuC4cbrWN48DDT4WuxuswAT8X11UVnTIbIcZba9GVHKYNkCjbb/n4XIxVxKvRKPRwS2TJRhCXlLyD5mwMiI0PeJcwSX6YD0gpvwkhw1k+gNczBZRC21st61P71GFfTKAvpluhHCGmRbKscHzHCo+Sh3v8CINYxq0Wo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727858983; c=relaxed/simple; bh=Z3W9pITpq0sbIFI0A9BC3q6ZdGLqjWbHGQ2enl9bsXE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Zr+URHd6H3BNJdGm0klNDs2UdWtaqj6kcnJadILku7PUijgGT5eubI1TOJGiVlAk8aDZlmGrBgmx7/PgGlzYAmI3rjQNdyjzIc9X8h6IZ9p1nwFg7xRtxEWhelNk3TnSD0KXASldqBZJq+3rI87eZvn4rVT9/8M3vVDndDbt4ZA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=hGU9YsIB; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hGU9YsIB" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=l7ArBZRc7vYZ5jGHtpDzZjoriCFDjp6bUpLmSZ4ec20=; b=hGU9YsIB/AsKEnL6rYFzcp3c5p OyEMI+ExZqWn6dtg8FN0pyXfDCNY2CfhvOhEMYfsfv40OLZBCJfq6lChOKhMqy2vEb6V0M7F/CtLZ xlcs6tevwQEvY8wtwNXEFjhYMDQG2E1XEwcapeZqet6xhXk2LJAZqCa4fArAeoOyIUG0iqeVo+uW2 s6SnE5MlO0mSSReVXPjCLefNLiNjYdZ1pCVQHcKnGcDUXPnS63ejiQR8/6HagFkuPciN8p2pJtOcA 9vxCZraCVbZW3E6HjeQBRmak2IJRgcbdU3kJurCEsyghxRCIMYPFmOIfy+nbeIdovnKVQdSKk9u4c bIqXny9Q==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1svv37-00000003Rzz-0pHH; Wed, 02 Oct 2024 08:49:33 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 29414300777; Wed, 2 Oct 2024 10:49:32 +0200 (CEST) Date: Wed, 2 Oct 2024 10:49:32 +0200 From: Peter Zijlstra To: Mike Galbraith Cc: Vishal Chourasia , linux-kernel@vger.kernel.org, Ingo Molnar , Vincent Guittot , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , luis.machado@arm.com Subject: Re: sched/fair: Kernel panics in pick_next_entity Message-ID: <20241002084932.GN5594@noisy.programming.kicks-ass.net> References: <20240930144157.GH5594@noisy.programming.kicks-ass.net> <55a2acefffb8c99e4234bd18656a75625447c2d0.camel@gmx.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55a2acefffb8c99e4234bd18656a75625447c2d0.camel@gmx.de> On Tue, Oct 01, 2024 at 10:30:26AM +0200, Mike Galbraith wrote: > On Tue, 2024-10-01 at 00:45 +0530, Vishal Chourasia wrote: > > > > > for sanity, I ran the workload (kernel compilation) on the base commit > > where the kernel panic was initially observed, which resulted in a > > kernel panic, along with it couple of warnings where also printed on the > > console, and a circular locking dependency warning with it. > > > > Kernel 6.11.0-kp-base-10547-g684a64bf32b6 on an ppc64le > > > > ------------[ cut here ]------------ > > > > ====================================================== > > WARNING: possible circular locking dependency detected > > 6.11.0-kp-base-10547-g684a64bf32b6 #69 Not tainted > > ------------------------------------------------------ > > ... > > > --- interrupt: 900 > > se->sched_delayed > > WARNING: CPU: 1 PID: 27867 at kernel/sched/fair.c:6062 unthrottle_cfs_rq+0x644/0x660 > > ...that warning also spells eventual doom for the box, here it does > anyway, running LTPs cfs_bandwidth01 testcase and hackbench together, > box grinds to a halt in pretty short order. > Right, I've picked up your patch for sched/urgent. But this does make me question Vishal's setup. He said all he does is compile a kernel, but afaik no regular setup uses CFS bandwidth by default. So something is 'special' at his end that he's not been telling us about. Vishal, could you expand upon your configuration? How come you're using CFS bandwidth, what else is special?