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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C30E3C28D13 for ; Mon, 22 Aug 2022 08:40:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233008AbiHVIks (ORCPT ); Mon, 22 Aug 2022 04:40:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50360 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233728AbiHVIk1 (ORCPT ); Mon, 22 Aug 2022 04:40:27 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E2172CE08; Mon, 22 Aug 2022 01:40:27 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id D610F3409E; Mon, 22 Aug 2022 08:40:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1661157625; h=from:from:reply-to: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=VcbvCJQ1zOc64Py1K/gbGV3Y6GJOOhSUWGI7rx6TWww=; b=ER9unaPf2hCEbRjHPDyTECb5vRi26FhhiGjg9bwvnzF+/0XCprkC8OBBhFJFMtwWj68Xtj 1m/Ax427gI//N003gKJD5Ojq4PEsF/RPchJSxVxb81mm03xXrVWIiDxqVXd+dH21I31QcY IUdg4ZtD4i10l+Gf1w4Oj42sRq/lgiY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1661157625; h=from:from:reply-to: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=VcbvCJQ1zOc64Py1K/gbGV3Y6GJOOhSUWGI7rx6TWww=; b=pxebau4ppmaoquiGchCiweeVSANLj6ZznuTd4F5MvyGMIFQzGy3xND1GIvbjLtLY1zbG6Y DceKPjfysbZd4KBw== Received: from suse.de (mgorman.udp.ovpn2.nue.suse.de [10.163.43.106]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 9AC6A2C142; Mon, 22 Aug 2022 08:40:23 +0000 (UTC) Date: Mon, 22 Aug 2022 09:40:19 +0100 From: Mel Gorman To: Ingo Molnar Cc: Linus Torvalds , David Hildenbrand , linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, Andrew Morton , Greg Kroah-Hartman , Axel Rasmussen , Peter Xu , Hugh Dickins , Andrea Arcangeli , Matthew Wilcox , Vlastimil Babka , John Hubbard , Jason Gunthorpe , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt Subject: Re: [PATCH v2] sched/all: Change all BUG_ON() instances in the scheduler to WARN_ON_ONCE() Message-ID: <20220822084019.wcezy5dyy5slg4k7@suse.de> References: <20220808073232.8808-1-david@redhat.com> <1a48d71d-41ee-bf39-80d2-0102f4fe9ccb@redhat.com> <20220815144143.zjsiamw5y22bvgki@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 21, 2022 at 01:28:58PM +0200, Ingo Molnar wrote: > > * Mel Gorman wrote: > > > For the rest, I didn't see obvious recovery paths that would allow the > > system to run predictably. Any of them firing will have unpredictable > > consequences (e.g. move_queued_task firing would be fun if it was a > > per-cpu kthread). Depending on which warning triggers, the remaining life > > of the system may be very short but maybe long enough to be logged even > > if system locks up shortly afterwards. > > Correct. I'd prefer to keep all these warnings 'simple' - i.e. no attempted > recovery & control flow, unless we ever expect these to trigger. > I generally hope we never expect a warning to trigger until of course it does :P > I.e. instead of adding a 'goto' I'd prefer if we removed most of the ones > you highlighted. But wanted to keep this first patch simple. > The only one I would push back on is claming cpupri_find_fitness() so it does not access outside the bounds of an array after a warning triggers. For the rest, I've no strong objection to recovering given the nature of the BUGs you are converting. If any of them *did* trigger, it would be more important to fix the issue than recover the warning. So other than the out-of-bounds array access which I'd like to see clamped just in case; Acked-by: Mel Gorman -- Mel Gorman SUSE Labs