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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A77AC433F5 for ; Fri, 12 Nov 2021 07:51:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4D71260FE7 for ; Fri, 12 Nov 2021 07:51:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233016AbhKLHxv (ORCPT ); Fri, 12 Nov 2021 02:53:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35030 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230464AbhKLHxt (ORCPT ); Fri, 12 Nov 2021 02:53:49 -0500 Received: from mail-yb1-xb2c.google.com (mail-yb1-xb2c.google.com [IPv6:2607:f8b0:4864:20::b2c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 10EECC061766 for ; Thu, 11 Nov 2021 23:50:59 -0800 (PST) Received: by mail-yb1-xb2c.google.com with SMTP id e136so21568495ybc.4 for ; Thu, 11 Nov 2021 23:50:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=8hsJfBjpLQBnNYoC8zh5y1uUfpVlm2S4eitLUmrS0SI=; b=JBV6L1OHMnp6AQ9vM+jo8Lrg6xtxiG3nXWTz5o5RSYI39xgwe0ng8XHLP+9bwUfd/o hLaQgG26lHY6x1a83Ds1FJTIr5fS/v/wX3KIBeoHC1nprvQVCHfzIE+4aCnJeLuyehSH 2ihTrpFqGF2kb8SwhGO6OW+FSEbQjeuKjzY1+UfqqOXAbJihZjyMqZe2EH/Rxf+EAgS8 0QbRoGuuGB7teAMvE3SCmg8nvr7PHDXsd7df5FoOjjfmgCXvzWDRGt5tG/3pum5zp4WI y7ZVZjpA6HR0bWMug27ecBkz14v4Tk7SdQTOqRatzShMMu8ZQwXakG74WjW7H5JOHl4H q4FQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=8hsJfBjpLQBnNYoC8zh5y1uUfpVlm2S4eitLUmrS0SI=; b=yL00qa/lc8ngX8w23i99cSaJhuzw0rq7DtZ8zwmZQRlR/fb4T9lEwcGWTABqG+8nRm VQQqDFO7h+vNp2ptXjf65Cq3hJPXLKH+ozZzJ44JZmyFrw7JJ6+OHeKVq/quRHAj6swm mLlFOPRTEtsyZdv2vRei6jUIpdYLovi4lCI/VjyrfTOXOkgyp/7E1xXVqx03K+FAdgEP IN/x1DfuOOa/kQxQSTE3jUEKL0wAsk+4ZZbXEzBur7uddJ02sBxcvDDxOxZlpPkkfyVo b7RNizPJ2gFeFPP6C3yQ5jCc7Mcwf44hrXl1G5B8RgYrwYx9hsiCYNQ053z8bbhKr5t3 b6Ig== X-Gm-Message-State: AOAM531lds88vhR+9NHdc1Yj2qbHBFhTAKh5W/dsl1B494/pWBq6O1rA 0C5R/DcZq5dl7c649E75/zMl6WZY+oRnxLWJ/IxK6w== X-Google-Smtp-Source: ABdhPJxYnWdOcV5iPRaYM7MejstD+Cx3j6SwdJdRMaK1kX1sZPdfnECqq3bvWSXTyWwZRDugM5kEUr51wLDc3Vui35E= X-Received: by 2002:a25:a427:: with SMTP id f36mr14333170ybi.245.1636703458115; Thu, 11 Nov 2021 23:50:58 -0800 (PST) MIME-Version: 1.0 References: <20211109213847.GY174703@worktop.programming.kicks-ass.net> In-Reply-To: From: Vincent Guittot Date: Fri, 12 Nov 2021 08:50:46 +0100 Message-ID: Subject: Re: printk deadlock due to double lock attempt on current CPU's runqueue To: Sultan Alsawaf Cc: Peter Zijlstra , Anton Vorontsov , Ben Segall , Colin Cross , Daniel Bristot de Oliveira , Daniel Vetter , David Airlie , Dietmar Eggemann , dri-devel@lists.freedesktop.org, Ingo Molnar , John Ogness , Juri Lelli , Kees Cook , linux-kernel@vger.kernel.org, Maarten Lankhorst , Maxime Ripard , Mel Gorman , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Thomas Zimmermann , Tony Luck , mkoutny@suse.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 10 Nov 2021 at 20:50, Sultan Alsawaf wrote: > > On Wed, Nov 10, 2021 at 10:00:35AM +0100, Vincent Guittot wrote: > > Is it the same SCHED_WARN_ON(rq->tmp_alone_branch != > > &rq->leaf_cfs_rq_list); that generates the deadlock on v5.15 too ? > > > > one remaining tmp_alone_branch warning has been fixed in v5.15 with > > 2630cde26711 ("sched/fair: Add ancestors of unthrottled undecayed cfs_rq") > > I should clarify that I didn't actually reproduce the issue on v5.15; I just saw > that the call chain leading to the deadlock still existed in v5.15 after looking > through the code. Thanks for the clarification > > Failing the SCHED_WARN_ON(rq->tmp_alone_branch != &rq->leaf_cfs_rq_list); assert > is extremely rare in my experience, and I don't have a reproducer. It has only > happened once after months of heavy usage (with lots of reboots too, so not with > crazy high uptime). > > Sultan