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Subject: Re: [PATCH] perf: fix panic by disable ftrace on fault.c
To:     Dave Hansen <dave.hansen@intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        "open list:X86 MM" <linux-kernel@vger.kernel.org>,
        "open list:BPF (Safe dynamic programs and tools)" 
        <netdev@vger.kernel.org>,
        "open list:BPF (Safe dynamic programs and tools)" 
        <bpf@vger.kernel.org>
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From:   =?UTF-8?B?546L6LSH?= <yun.wang@linux.alibaba.com>
Message-ID: <4cba7088-f7c8-edcf-02cd-396eb2a56b46@linux.alibaba.com>
Date:   Wed, 15 Sep 2021 09:56:33 +0800
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On 2021/9/15 上午12:16, Dave Hansen wrote:
> On 9/14/21 12:23 AM, 王贇 wrote:
>>
>> On 2021/9/14 上午11:02, 王贇 wrote:
>> [snip]
>>> [   44.133509][    C0] traps: PANIC: double fault, error_code: 0x0
>>> [   44.133519][    C0] double fault: 0000 [#1] SMP PTI
>>> [   44.133526][    C0] CPU: 0 PID: 743 Comm: a.out Not tainted 5.14.0-next-20210913 #469
>>> [   44.133532][    C0] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
>>> [   44.133536][    C0] RIP: 0010:perf_swevent_get_recursion_context+0x0/0x70
>>> [   44.133549][    C0] Code: 48 03 43 28 48 8b 0c 24 bb 01 00 00 00 4c 29 f0 48 39 c8 48 0f 47 c1 49 89 45 08 e9 48 ff ff ff 66 2e 0f 1f 84 00 00 00 00 00 <55> 53 e8 09 20 f2 ff 48 c7 c2 20 4d 03 00 65 48 03 15 5a 3b d2 7e
>>> [   44.133556][    C0] RSP: 0018:fffffe000000b000 EFLAGS: 00010046
>> Another information is that I have printed '__this_cpu_ist_bottom_va(NMI)'
>> on cpu0, which is just the RSP fffffe000000b000, does this imply
>> we got an overflowed NMI stack?
> 
> Yep.  I have the feeling some of your sanitizer and other debugging is
> eating the stack:

Could be, in another thread we have confirmed the exception stack was
overflowed.

> 
>> [   44.134987][    C0]  ? __sanitizer_cov_trace_pc+0x7/0x60
>> [   44.135005][    C0]  ? kcov_common_handle+0x30/0x30
> 
> Just turning off tracing for the page fault handler is papering over the
> problem.  It'll just come back later with a slightly different form.
> 

Cool~ please let me know when you have the proper approach.

Regards,
Michael Wang