Re: [PATCH] perf: fix panic by disable ftrace on fault.c

On 2021/9/15 上午12:16, Dave Hansen wrote:

On 9/14/21 12:23 AM, 王贇 wrote:

quoted

On 2021/9/14 上午11:02, 王贇 wrote:
[snip]

quoted

[   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.

quoted

[   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