linux-kernel - [PATCH v4 0/2] rcu: Display registers of self-detected stall as far as possible

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Date:   Thu, 4 Aug 2022 10:34:18 +0800
From:   Zhen Lei <thunder.leizhen@...wei.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>,
        "Mel Gorman" <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Valentin Schneider <vschneid@...hat.com>,
        <linux-kernel@...r.kernel.org>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Neeraj Upadhyay <quic_neeraju@...cinc.com>,
        "Josh Triplett" <josh@...htriplett.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Joel Fernandes <joel@...lfernandes.org>, <rcu@...r.kernel.org>
CC:     Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH v4 0/2] rcu: Display registers of self-detected stall as far as possible

v3 --> v4:
1. To avoid undo/redo, merge patch 1-2 in v3 into one.

v2 --> v3:
1. Patch 1 Add trigger_single_cpu_backtrace(cpu) in synchronize_rcu_expedited_wait()
   Subsequently, we can see that all callers of dump_cpu_task() try
   trigger_single_cpu_backtrace() first. Then I do the cleanup in Patch 2.
2. Patch 3, as Paul E. McKenney's suggestion, push the code into dump_cpu_task().

For newcomers:
Currently, dump_cpu_task() is mainly used by RCU, in order to dump the
stack traces of the current task of the specified CPU when a rcu stall
is detected.

For architectures that do not support NMI interrupts, registers is not
printed when rcu stall is self-detected. This patch series improve it.


v2:
https://lkml.org/lkml/2022/7/27/1800

Zhen Lei (2):
  sched/debug: Try trigger_single_cpu_backtrace(cpu) in dump_cpu_task()
  sched/debug: Show the registers of 'current' in dump_cpu_task()

 kernel/rcu/tree_stall.h |  8 +++-----
 kernel/sched/core.c     | 14 ++++++++++++++
 kernel/smp.c            |  3 +--
 3 files changed, 18 insertions(+), 7 deletions(-)

-- 
2.25.1