From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olivier Brunel Subject: Re: bpfilter causes a leftover kernel process Date: Wed, 5 Sep 2018 17:52:43 +0200 Message-ID: <20180905175243.78a6ba81@jjacky.com> References: <20180826180816.04ef7d16@jjacky.com> <20180827183122.0b4ac65e@jjacky.com> <20180828033500.g3siwst5h2ckewwb@ast-mbp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, daniel@iogearbox.net To: Alexei Starovoitov Return-path: Received: from mail.jjacky.com ([23.29.69.116]:39045 "EHLO mail.jjacky.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726046AbeIEVgc (ORCPT >); Wed, 5 Sep 2018 17:36:32 -0400 In-Reply-To: <20180828033500.g3siwst5h2ckewwb@ast-mbp> Sender: netdev-owner@vger.kernel.org List-ID: Hi, Quick follow-up on this: - first off, Arch devs have updated their kernel config so the next kernel will not have bpfilter enabled anymore, thus avoiding any issue. - having said that, I've found a neasy way to reproduce it in an Arch VM, in case you're interested : Boot the latest Arch ISO[1] which now contains a kernel 4.18.5 and do a very basic installation, pretty much just: # pacstrap /mnt base # genfstab -U /mnt >> /mnt/etc/fstab And of course install your boot loader of choice. Then boot the brand new system, log in and make sure the helper is actually started, i.e. `modprobe bpfilter` -- Now halt. You'll see in the end that systemd complains that it can't unmount /oldroot (EBUSY), aka the root fs; and that's because of the bpfilter helper, which wasn't killed because it's seen as a kernel thread due to its empty command line and therefore not signaled. Cheers, [1] https://www.archlinux.org/download/