linux-kernel - [PATCH 0/4] rcu/tracing/extable: Fix stack dump when RCU is not watching

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Message-Id: <20170922221543.900812109@goodmis.org>
Date:   Fri, 22 Sep 2017 18:15:43 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     ngo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH 0/4] rcu/tracing/extable: Fix stack dump when RCU is not watching

I'm currently running this through my test suite, but wanted to get
review or acks, so that I can send this right off to Linus before rc2.
I need these to base my new work on.

Basically if a stack trace happens (say from a WARN()) when RCU is not
watching (like going to or coming from idle, or bringing down or up
a CPU), the stack trace can cause RCU issues because it requires RCU to
be watching.

We use rcu_nmi_enter() for this case, as these cases behave similar to
an NMI (can happen pretty much anywhere).

Paul E. McKenney (1):
      rcu: Allow for page faults in NMI handlers

Steven Rostedt (VMware) (3):
      extable: Consolidate *kernel_text_address() functions
      extable: Enable RCU if it is not watching in kernel_text_address()
      tracing: Remove RCU work arounds from stack tracer

----
 kernel/extable.c           | 45 +++++++++++++++++++++++++++++++--------------
 kernel/rcu/tree.c          | 10 ++++++++++
 kernel/trace/trace_stack.c | 15 ---------------
 3 files changed, 41 insertions(+), 29 deletions(-)