Re: Allocation failure with subsequent kernel crash

Hi Matthew,

On 08/20/2018 08:03 AM, tedheadster wrote:

On Mon, Aug 20, 2018 at 1:22 AM, Alexei Starovoitov
[off-list ref] wrote:

quoted

I don't remember vzalloc issues that was fixed in this area.
4.14 kernel is quite old. Since then syzbot found few mem
related bugs that were fixed.
please try to reproduce on the latest tree.

Alexei,
  I get this panic with two very recent kernels: 4.18.0 and 4.17.14. I
do not think this has been fixed. I am still trying to bisect it, but
sometimes it takes 5 hours for the panic to occur.

I've been looking into it a bit today and still am. Given you've seen
this on x86_32 and also on older kernels, I presume JIT was not involved
(/proc/sys/net/core/bpf_jit_enable is 0). Do you run any specific workload
until you trigger this (e.g. fuzzer on BPF), or any specific event that
triggers at that time after ~5hrs? Or only systemd on idle machine? Have
you managed to reproduce this also elsewhere? Bisect seems indeed painful
but would help tremendously; perhaps also dumping the BPF insns that are
loaded at that point in time.

Thanks a lot,
Daniel

- Matthew Whitehead