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[209.132.180.67]) by mx.google.com with ESMTP id 38si870871otm.189.2020.03.19.01.03.04; Thu, 19 Mar 2020 01:03:56 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=GEVQs03g; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726603AbgCSICC (ORCPT + 99 others); Thu, 19 Mar 2020 04:02:02 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:40797 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725768AbgCSICC (ORCPT ); Thu, 19 Mar 2020 04:02:02 -0400 Received: by mail-pl1-f194.google.com with SMTP id h11so721604plk.7 for ; Thu, 19 Mar 2020 01:02:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=u9I0K1i6lFI4gaPnMkUskjsZvi7Mdl+pohuc3TDlzKo=; b=GEVQs03gACbZupRv7CyqkNCE3CBeiq3/FPKXyXCXOH8lDEtiLQ0qdAxd01QgR1NZAh lCV0cOzxIWKZVuOSoEM2W2O2bFRtpfmz7zfPKcioBYDWm5alhAVWqicfDcdpItjmK8Nn H/hOGO13MskJfqDqYqv6bnsZSNbN8Gq0gJIKLazYvsFU72BSJRe+MGWAd9m7vmPcLnsf PFcULofNC1OhaVZ68ZsWZVDa17G1rd5zy8tsA7pzFFtGip/ZAHnS38zGSZO2/ovH9o9S 1gbfKVzzTj4ETAAgsL9+MT2CckKm88qzKA8vUhJduvUM+0ITPzsv4wWsiwG8DoS+GrG5 sH4g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=u9I0K1i6lFI4gaPnMkUskjsZvi7Mdl+pohuc3TDlzKo=; b=jLN3ULdczALh2uxGFrmXSJHUY/GnfTB7frDTGNPV9//hVVhQoaJVnNdOdPZomuxVx2 2/sQyiKno+pG1LafsAuIzybbeRAoC3W++OMADa3iSBVp7F5SqAlaPZEoBzy7qYdjJ6R1 e9GyZtKf4UYEAGOza0eEtmHunGH/B/TWWrxzqHEmj4MnqX/Lttq9gJ3R15Kt9AAt9zRQ CdNPt4gCmhWnHPuzwyeiWwAZbNSuGZ62e0TIWeF5CN+KBftvpzbYsuVPq5KnuYJfSHQL tkjaZV9Jh8NUiZiHN25j8V7+0Xdv5nP92DA+i8n0ayL7/bu/m6pGbIOv2XNKdeGA0WUi pazA== X-Gm-Message-State: ANhLgQ2bwyKzjmWrGB1M5sziGlK0/dp6Y/fEGVG1XLvX0e3ZhKkNKpol UUY/s+VDwJmTL5p7EDj7ygo= X-Received: by 2002:a17:90a:ff05:: with SMTP id ce5mr2370717pjb.83.1584604919731; Thu, 19 Mar 2020 01:01:59 -0700 (PDT) Received: from localhost ([2401:fa00:8f:203:5bbb:c872:f2b1:f53b]) by smtp.gmail.com with ESMTPSA id e14sm1344303pfn.196.2020.03.19.01.01.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Mar 2020 01:01:58 -0700 (PDT) Date: Thu, 19 Mar 2020 17:01:56 +0900 From: Sergey Senozhatsky To: Valdis =?utf-8?Q?Kl=C4=93tnieks?= Cc: Sergey Senozhatsky , Eugeniu Rosca , linux-kernel@vger.kernel.org, John Ogness , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Ingo Molnar , Thomas Gleixner , Peter Zijlstra , Jisheng Zhang , Sebastian Andrzej Siewior , Andrew Gabbasov , Dirk Behme , Eugeniu Rosca Subject: Re: [RFC PATCH 3/3] watchdog: Turn console verbosity on when reporting softlockup Message-ID: <20200319080156.GC24020@google.com> References: <20200315170903.17393-1-erosca@de.adit-jv.com> <20200315170903.17393-4-erosca@de.adit-jv.com> <20200317021818.GD219881@google.com> <20200318180525.GA5790@lxhi-065.adit-jv.com> <20200319064836.GB24020@google.com> <16373.1584603506@turing-police> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <16373.1584603506@turing-police> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/03/19 03:38), Valdis Klētnieks wrote: > On Thu, 19 Mar 2020 15:48:36 +0900, Sergey Senozhatsky said: > > > So the issue is that when we bump `console_loglevel' or `ignore_loglevel' > > we lift restrictions globally. For all CPUs, for all contexts which call > > printk(). This may have negative impact. Fuzzing is one example. It > > usually generates a lot of printk() noise, so lifting global printk() > > log_level restrictions does cause problems. I recall that fuzzing people > > really disliked the > > old_level = console_loglevel > > console_loglevel = new_level > > .... > > console_loglevel = old_level > > > > approach. Because if lets all CPUs and tasks to pollute serial logs. > > While what we want is to print messages from a particular CPU/task. > > Well... how does this sound for a RFC idea? We already have CONFIG_PRINTK_TIME > and CONFIG_PRINTK_CALLER. How about adding an option to allow printing the > calling CPU as well, or just extend CALLER to print [pid/cpu] rather than just > [pid]? IIRC, CONFIG_PRINTK_CALLER prints pid when printk() caller is a running task, and CPU-id otherwise. It was added by fuzzing people, because it's almost (or "simply") impossible to get through serial logs sometimes. -ss