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Date:   Wed, 22 May 2019 15:51:06 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Song Liu <songliubraving@fb.com>
Cc:     Kairui Song <kasong@redhat.com>, Alexei Starovoitov <ast@fb.com>,
        lkml <linux-kernel@vger.kernel.org>,
        Kernel Team <Kernel-team@fb.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        "bpf@vger.kernel.org" <bpf@vger.kernel.org>
Subject: Re: Getting empty callchain from perf_callchain_kernel()
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On Mon, May 20, 2019 at 05:22:12PM +0000, Song Liu wrote:
> I think this is still the best fix/workaround here? And only one level 
> of stack trace should be OK for tracepoint? 

No. That's still completely broken.