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[178.24.245.106]) by smtp.gmail.com with ESMTPSA id u25sm25874774wml.17.2020.03.15.10.09.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Mar 2020 10:09:33 -0700 (PDT) From: Eugeniu Rosca X-Google-Original-From: Eugeniu Rosca To: linux-kernel@vger.kernel.org Cc: Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Ingo Molnar , Thomas Gleixner , Peter Zijlstra , Jisheng Zhang , Valdis Kletnieks , Sebastian Andrzej Siewior , Andrew Gabbasov , Dirk Behme , Eugeniu Rosca Subject: [RFC PATCH 0/3] Fix quiet console in pre-panic scenarios Date: Sun, 15 Mar 2020 18:09:00 +0100 Message-Id: <20200315170903.17393-1-erosca@de.adit-jv.com> X-Mailer: git-send-email 2.25.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dear community, The motivation behind this seris is to save days/weeks, if not months, of debugging efforts for users who: * experience an issue like softlockup/hardlockup/hung task/oom, whose reproduction is not clear and whose occurrence rate is very low * are constrained to use a low loglevel value (1,2,3) in production * mostly rely on console logs to debug the issue post-mortem (e.g. saved to persistent storage via e.g. pstore) As pointed out in the last patch from this series, under the above circumstances, users might simply lack any relevant logs during post-mortem analysis. Why this series is marked as RFC is because: * There are several possible approaches to turn console verbosity on and off. Current series employs the 'ignore_loglevel' functionality, but an alternative way is to use the 'console_loglevel' variable. The latter is more intrusive, hence the former has been chosen as v1. * Manipulating 'ignore_loglevel' might be seen as an abuse, especially because it breaks the expectation of users who assume the system to be dead silent after passing loglevel=0 on kernel command line. Thank you for your comments! Eugeniu Rosca (3): printk: convert ignore_loglevel to atomic_t printk: add console_verbose_{start,end} watchdog: Turn console verbosity on when reporting softlockup include/linux/printk.h | 10 ++++++++++ kernel/printk/printk.c | 30 ++++++++++++++++++++++++++---- kernel/watchdog.c | 4 ++++ 3 files changed, 40 insertions(+), 4 deletions(-) -- 2.25.0