From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: Allocation failure with subsequent kernel crash Date: Mon, 20 Aug 2018 21:29:45 +0200 Message-ID: <05825446-e8aa-a983-3fc6-4dc8e81cba57@iogearbox.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: LKML , Network Development , Ingo Molnar , Thomas Gleixner , Alexei Starovoitov To: whiteheadm@acm.org, Alexei Starovoitov Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi Matthew, On 08/20/2018 08:03 AM, tedheadster wrote: > On Mon, Aug 20, 2018 at 1:22 AM, Alexei Starovoitov > wrote: >> 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 >