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Date: Tue, 29 Nov 2016 13:43:23 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Vince Weaver <vincent.weaver@maine.edu>,
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        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        "dvyukov@google.com" <dvyukov@google.com>
Subject: Re: perf: fuzzer BUG: KASAN: stack-out-of-bounds in __unwind_start
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On Mon, Nov 28, 2016 at 11:52:41PM -0600, Josh Poimboeuf wrote:

> Did a little digging on git blame and found the following commit (which
> seems to be the cause of the KASAN warning and missing stack dump):
> 
>   bc1dce514e9b ("rcu: Don't use NMIs to dump other CPUs' stacks")
> 
> I presume this commit is still needed because of the NMI printk deadlock
> issues which were discussed at Kernel Summit.  I guess those issues need
> to be sorted out before the above commit can be reverted.

Also, I most always run with these here patches applied:

  https://lkml.kernel.org/r/20161018170830.405990950@infradead.org

People are very busy polishing the turd we call printk, but from where
I'm sitting its terminally and unfixably broken.

I should certainly add a revert of the above commit to the stack of
patches I carry.