> We noticed that this only happens with precise_ip >= 2. This is caused by > setup_pebs_fixed_sample_data() using pens->real_ip: > > set_linear_ip(regs, pebs->real_ip);
With precise_ip == 1 the IP will be one instruction behind. That's the only difference to 2 or 3. So something about the actual instruction confuses the unwinder. I would check if there is anything special about these IPs: > 0xfffffe00004d1f78 entry_SYSCALL_64 > 0xfffffe00004d1fa0 entry_SYSCALL_64 > 0xfffffe00004d1fd8 entry_SYSCALL_64 > > For our use case, we do need precise_ip=2. So we would like suggestions to > fix the > warning and/or to avoid double fault. As a minimum, I would just add an && !in_nmi() to the warning. Clearly it doesn't make sense to print a warning that overflows the stack. -Andi
