From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 6CEA9632 for ; Fri, 5 Apr 2024 00:10:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712275856; cv=none; b=WKfAgzCEu6SRoT0kbiIZZ38Nm5uWDXjL0h7kcxX98zzRIMt0ZqOAASC4jk5g/+B89vR3pRLxgIp44eoZAy7EnO5xgetJXGirghcqSvvnI7E5z1wZDdPTt/H6xstz+JHvM/G9m7qfTI2BANlXV06+iMvgLpl8j6iOuILGsf3w43c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712275856; c=relaxed/simple; bh=BmBMLXUxUdQY6RZx6aOTeW4K15net+pmM7o/+Du4xfw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Q7KAN/7chVlZxK/dBuVLWUfOkOWiZd+em2UF5noa5ObZZZgWt6VwDQfPhvtnSYKhSFfZrWLXBhypxk99fh6Jal685b8kO5KDoLYykPa5yCrxetSyjXo2Aca1S4lmFRg/OC0FQx6WkiRdONAvUnvRNJ0PnCnd2tZr8zEk0LzmSMQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=iCm8ypvX; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iCm8ypvX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1712275853; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kPChRIv8A7YfUteYh5+G6hC7ECPnSAUjkzqqJ0L1F/Y=; b=iCm8ypvX+3CZZ4jXItm3aJfV+6UgpQB2VKrT6TnHUYLO3RyC9PSggo+Ck2JvyygfhCsFdM 9oIaZpMGfx4dAm26a2KaK8LQYcQ2YeXVXwrGnS/CnGm3KQpRaJTbSF0Df7QmwH5qrfSQzV LhtX5jV+wUhIM1/cBjXiCxi0SUhtuWA= Received: from mail-oi1-f200.google.com (mail-oi1-f200.google.com [209.85.167.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-418-8h-8ousONiuGiaGcOU8dMg-1; Thu, 04 Apr 2024 20:10:51 -0400 X-MC-Unique: 8h-8ousONiuGiaGcOU8dMg-1 Received: by mail-oi1-f200.google.com with SMTP id 5614622812f47-3c3c73e89fdso1350943b6e.0 for ; Thu, 04 Apr 2024 17:10:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712275851; x=1712880651; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=kPChRIv8A7YfUteYh5+G6hC7ECPnSAUjkzqqJ0L1F/Y=; b=sq0nwrUrenTMsYk7CxmZ12tdsyFNhVtUZ7oS99L0dQp7GOqVn9+nRWYVC4Grz8QiYT NSClQgeSGJJkagUHfNoxO1+ElwGjX9/rgvEbfa+k9dOt6gzDfZNP1xZEQWnJXu+TnBsc Mp7OFv4acKp/U4UhU6yhmNfYFHA1sS7fF4FIj3SrZ/YO25guCQaJMeHLc6sMKwC6AVIB v3C4Kn0xjyE4BamFbIpDI7QzNNt3iy0iUn2iao6cY2Q64Wq8RQdmiNNdwE3A1KHZV6/a 8Ukt6V1JddlHqxs1hJLLEM/CbMogQoC97DqK2e+TyVR2alc0LU901iVFhkrlTJK9pXK+ apgQ== X-Forwarded-Encrypted: i=1; AJvYcCXwBad+Rw5KElVYPDGlL4OQhL+bZ5RBX7ZnD62LSGoSlaGrqHqIQXp3qwzSAGSTYCR4hgRy9r5YFpom2Z1g+O7DOaEUXL1DYNSj3pMx X-Gm-Message-State: AOJu0YxjAA44m2GgFQqa4m9cLqMQ4E4oqZ0D5N6pUq4PvDiY6L+wEpzu NsnSXGXSiGlrFZer6MevhL8D238eJL44HiUg7wN3E1zCqs8NyiLoJV3qSUlHf9a+PRV3s+yIyGk gD9NWguA0g1OSxDO18taFgebXQezawDD7kdivH5pwMaL0jjsQpxRTN1E6xYNLrg== X-Received: by 2002:a05:6808:1a94:b0:3c3:e78d:f1be with SMTP id bm20-20020a0568081a9400b003c3e78df1bemr3224535oib.57.1712275851133; Thu, 04 Apr 2024 17:10:51 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHYvDwwFdzbAzzTkv9y5a2UnJif8xQ//ZZbKdgL0bzXnHd+ilqRDAJVDXGbLCNvPpqaWSRZYg== X-Received: by 2002:a05:6808:1a94:b0:3c3:e78d:f1be with SMTP id bm20-20020a0568081a9400b003c3e78df1bemr3224503oib.57.1712275850193; Thu, 04 Apr 2024 17:10:50 -0700 (PDT) Received: from hatbackup ([71.217.47.58]) by smtp.gmail.com with ESMTPSA id cm23-20020a05622a251700b00432ed7d7b7csm213093qtb.85.2024.04.04.17.10.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Apr 2024 17:10:49 -0700 (PDT) Date: Thu, 4 Apr 2024 20:10:47 -0400 From: "John B. Wyatt IV" To: Sebastian Andrzej Siewior Cc: John Ogness , Petr Mladek , Clark Williams , Juri Lelli , Derek Barbosa , Bruno Goncalves , "John B. Wyatt IV" , LKML , linux-rt-users Subject: Re: NMIs reported by console_blast.sh with 6.6.20-rt25 Message-ID: References: <20240322122921.U3WRsO4X@linutronix.de> <20240402103414.KkkX5RuV@linutronix.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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240402103414.KkkX5RuV@linutronix.de> On Tue, Apr 02, 2024 at 12:34:14PM +0200, Sebastian Andrzej Siewior wrote: > > Just before the sysrq that crashes the system. > > so this is intentional. Yes. > > > > This is part of the console_blast.sh script that John Ogness sent me. > > > > Please see below: > … > > Okay. Then everything works as it should… Correct. > > > > > NMI Backtrace for 6.6.20-rt25 no forced preemption with tuned throughput-performance profile > > > > ----------------------------- > > > > > > This and the following backtrace shows the same picture: The CPU is > > > crashing due to proc/sysrq request and does CPU-backtraces via NMI and > > > polls in early_printk, waiting for the UART to become idle (probably). > > > > > > I don't see an issue here so far. > > > > Luis Goncalves discussed it with me after reading your response. Thank > > you for your help. The NMI was needed to flush the buffers upon the > > system crashing itself. Does this part about NMI watchdog need to be > > documented? > > Not sure about that one. There is an _a_ _lot_ to be printed from NMI > and the NMI watchdog might trigger if nothing is triggering the > NMI-watchdog during the print job. Also, the crash was requested. I reran the 6.6 test and no NMI was reported with fully preemptive and the realtime tuned profile. It was my error; my apologies for that. I did include more of logs if you want to see here for my 6.8 testing. https://lore.kernel.org/linux-rt-users/ZgWL2UyknaE2T70C@thinkpad2021/T/#u Sincerely, John Wyatt Software Engineer, Core Kernel Red Hat