From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olivier Brunel Subject: [PATCH 0/2] Re: bpfilter causes a leftover kernel process Date: Sat, 20 Oct 2018 19:39:55 +0200 Message-ID: <20181020173957.31239-1-jjk@jjacky.com> References: <20180826180816.04ef7d16@jjacky.com> <20180827183122.0b4ac65e@jjacky.com> <20180828033500.g3siwst5h2ckewwb@ast-mbp> <20180905175243.78a6ba81@jjacky.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Cc: Alexei Starovoitov , Daniel Borkmann , "Luis R . Rodriguez" , linux-kernel@vger.kernel.org, "David S . Miller" , Olivier Brunel To: Network Development Return-path: Received: from mail.jjacky.com ([23.29.69.116]:57419 "EHLO mail.jjacky.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727343AbeJUB6P (ORCPT ); Sat, 20 Oct 2018 21:58:15 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 16 Oct 2018 16:38:56 +0000 Alexei Starovoitov wrote: > On Wed, Sep 5, 2018 at 5:05 PM Olivier Brunel wrote: > > > > 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. > > thanks for tracking it down. > can somebody send a patch to give bpfilter non-empty cmdline? > I think that would be a better fix than tweaking all pid1s. So I'm not a kernel dev and this would be my first atttempt at a kernel patch, but I did have a look and came up with the following patch(es) to fix this. Hopefully I did things right. It adds a default command line ("usermodehelper") to such processes, so any & all such helpers will be seen as user process and not kernel threads, but there's also the possibility to specify a command line to use, here "bpfilter_umh" Cheers, Olivier Brunel (2): umh: Add command line to user mode helpers net: bpfilter: Set user mode helper's command line include/linux/umh.h | 1 + kernel/umh.c | 16 ++++++++++++++-- net/bpfilter/bpfilter_kern.c | 1 + 3 files changed, 16 insertions(+), 2 deletions(-) -- 2.19.0