From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f49.google.com (mail-ej1-f49.google.com [209.85.218.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6380113B286 for ; Mon, 26 Aug 2024 15:08:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724684932; cv=none; b=gNxC+80G3xFzK2oOmwtPdv+o2ajm4d22bgOUxNMKEmx1XTKxu2sCKTzh6Bm0MD16hsrsiCsybRR/8FxU7tFeNBvp4Xv3fHaApJnIclWRRuUmt9IBrDgvHY2r4419jHorXkczebOgNGQZL0hkKOZETnidk8jLYfFVUCAnJVA/WeI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724684932; c=relaxed/simple; bh=MTJMukaLubbeBjK2VCNHy37sPDU+QxLDErb2ug+AOlo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=RCfXAIQfOcqF5qz1Kw2Dj6T7xJtlRecQS1FTUrNHr93YreL9uhjoj2+lQ7p7NbVvuwkKeFfP+MsTUnumFLyIgPzIfuGpvZ3TUgtMiYLJpSrEWCz+amOCxOP+ol7YFAocxA4vOdIqyGWC5vFq6mJdss2zzJPiV/dCs4eRJt/UXOU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=Dq1AzZmM; arc=none smtp.client-ip=209.85.218.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="Dq1AzZmM" Received: by mail-ej1-f49.google.com with SMTP id a640c23a62f3a-a868b8bb0feso481797466b.0 for ; Mon, 26 Aug 2024 08:08:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1724684927; x=1725289727; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=yP9jwrqY8Nokmykhfmjq9A1OmczZ3ZsJp132H7d1xU8=; b=Dq1AzZmMPQPwA4mIIodEeNY5FR1hiHWa+JlL2aglhksg8chuKlfwPvsyXrFpBmG9F+ 2HuD/VkHPyg/MHnE7j26dtVjwPQqisZo6Bmjw4LEyAuhw+sOfxnZsCODVqFC8c/NavWs 8+MulLugJ4sWDvZ5oJVYVnfaVpuI+HmcxfZR7UkQVek7VGz54Eiei0+AHED4jvUlzhfx OMVl8LbjMdo4ETYgB4IgOf6kcKQwGGcj9p9ukAwycBSDUmO5rsQiYLmuTmNM87aDv0A+ jKjsZZ5smHjJCZflp9hfWMT9jjvD7ozNjiZHBivNe2xPT3QBhw8uxRT4pxJMsGepzU8r 4M0A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724684927; x=1725289727; h=in-reply-to: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=yP9jwrqY8Nokmykhfmjq9A1OmczZ3ZsJp132H7d1xU8=; b=hzP0M7Uh2jtsqdYnj2hj9PTRH+rpxNqb2Dg9GaJijIJsVRMS0B8w6QcrJ7twGi3Uig ben/5+DGtL0Z9k4P0ywJzUhE7+DOqluUfdcieg8pYiUrGNi6LNGwcoMFOH48IJVs+vLw OUpg301ZYFHqfWQJj8jVOicVnRfY/KauEFGWcZNbLoQypdzEsuB2Tqa1PrjoRYxkayUR +M7VY6t2UuGRoM/W0fddjNvcEsMrmyr6sQs89LTh7IATj2anKuYUJ2EBSdup/0Yfk/Qj TR3tRySSRIPhxGtpc0OB96xiYig1RXpygOqwDS+zOKNXL6+8OixBR/4UK9baY1GSMjI4 9Vng== X-Forwarded-Encrypted: i=1; AJvYcCV3rnKKikJUwTyAxPu7vkRlcuEILPQbrM6hVemERnpA+tZP9BP6++JVbAJhtZQymlv7mmLg1YVUqJYX6iM=@vger.kernel.org X-Gm-Message-State: AOJu0YxkJTnjHLQ6891gBZA/kixUdG/o0xyPk63uLouDMrug3z0c/U8n r+Dq6cAiheaMXUijZFas7RAjFubLYuwDlHtiQqcna7nvGTPK9smIGKK9lYAS7c4= X-Google-Smtp-Source: AGHT+IEsyoTCPsG2sCg/eK1b8PXETcwDGShijC+bkpt/aEJ18QP5ty/R1n/xTchmybueHHEM2XGwMQ== X-Received: by 2002:a17:907:c0d:b0:a86:c9f5:68df with SMTP id a640c23a62f3a-a86c9f57dbcmr284463466b.44.1724684927276; Mon, 26 Aug 2024 08:08:47 -0700 (PDT) Received: from pathway.suse.cz ([193.86.92.181]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a868f43661dsm674517666b.100.2024.08.26.08.08.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Aug 2024 08:08:47 -0700 (PDT) Date: Mon, 26 Aug 2024 17:08:45 +0200 From: Petr Mladek To: Derek Barbosa Cc: pmaldek@suse.com, williams@redhat.com, john.ogness@linutronix.de, tglx@linutronix.de, linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: test 1: was: Re: A Comparison of printk between upstream and linux-rt-devel Message-ID: References: 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: On Mon 2024-08-26 10:46:52, Derek Barbosa wrote: > On Mon, Aug 26, 2024 at 04:02:34PM +0200, Petr Mladek wrote: > > > If you have any other questions, please let me know. I would be happy to re-do > > > these tests with different kernels, configs + other variables and controls. > > > > It might be interesting to redo the 1st test without the crashdump. > > I wonder if console_flush_on_panic() would allow to see the panic > > backtrace with the stock kernel. > > Sure. > > I disabled the systemd kdump service unit via systemctl, and performed a reboot > to ensure that the crashkernel would not be armed. > > Performing a trial run of console_blast.sh shows results similar to what was > documented previously, with the difference being we don't reboot after the test > is completed and the kernel has effectively "crashed" via the sysrq-trigger. > > I have appended the serial console output as an attachment. You will see that we > do not get a final trace printed. > > [ 98.341743] sysrq: Show State > [ 98.341746] sysrq: Show State > [ 98.341805] sysrq: Show State > [ 98.341808] sysrq: Show State > [ 98.341812] task:systemd state:S > [ 98.341814] task:systemd state:S > [ 98.341814] stack:0 pid:1 tgid:1 ppid:0 flags:0x00000002 > [ 98.341818] stack:0 pid:1 tgid:1 ppid:0 flags:0x00000002 [...] > [ 111.777491] ? __pfx_hrtimer_wakeup+0x10/0x10 > ** 8555 printk messages dropped ** > [ 111.807996] ? __lruvec_stat_mod_folio+0x86/0xd0 > I see. I guess that the panic CPU ended in a deadlock in console_flush_on_panic() after it ignored the console_lock(). Otherwise, it would have flushed the last messages and rebooted. Best Regards, Petr