Kernel freeze when instrument `sys_enter_execve` and `mm_page_alloc_zone_locked` simultaneously

[vlad9486]

My system is:

$ uname -a
Linux localhost.localdomain 5.11.12-300.fc34.x86_64 #1 SMP Wed Apr 7 16:31:13 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

The minimal example:

#include "vmlinux.h"
#include <bpf/bpf_helpers.h>

char LICENSE[] SEC("license") = "Dual BSD/GPL";

SEC("tracepoint/syscalls/sys_enter_execve")
int execve(void *ctx)
{
	u32 value = 0;
	bpf_probe_read(&value, sizeof(value), ctx);
	return 0;
}

SEC("tracepoint/kmem/mm_page_alloc_zone_locked")
int page_alloc(void *ctx)
{
	u32 value = 0;
	bpf_probe_read(&value, sizeof(value), ctx);
	return 0;
}

It is a *.bpf.c file. In userspace do open, load and attach as usual. And entire system is freeze.

Obviously it is a kernel bug.

[chenhengqi]

I can't repro this.

[vlad9486]

@chenhengqi I tried in virtual machine and I cannot reproduce it too. The problem is somewhere in my system. I'll try to find precise conditions.