bpfilter: write fail messages with 5.15.x and centos 7.9.2009

[Holger Kiehl]

Hello,

I just upgraded the kernel from 5.10.x to 5.15.12 on an old Centos
7.9.2009 server. The kernel is build on a new fedora 35 system
via 'make binrpm-pkg'. With this I see the following errors:

   [  232.140766] bpfilter: Loaded bpfilter_umh pid 6327
   [  232.152144] bpfilter: write fail -32
   [  232.187175] bpfilter: Loaded bpfilter_umh pid 6330
   [  232.198540] bpfilter: write fail -32
   [  232.234604] bpfilter: Loaded bpfilter_umh pid 6332
   [  232.245916] bpfilter: write fail -32
   [  232.281883] bpfilter: Loaded bpfilter_umh pid 6337
   [  232.293222] bpfilter: write fail -32
   [  232.335798] bpfilter: Loaded bpfilter_umh pid 6380
   [  232.347157] bpfilter: write fail -32
   [  244.411821] bpfilter: Loaded bpfilter_umh pid 6712
   [  244.423216] bpfilter: write fail -32

These appear as soon as something is done via iptables (setting
something or just viewing). Is this something I need to worry
about? Under 5.10.81 I did not see these messages.

In Jul 2020 I see a similar report 'bpfilter logging write errors in
dmesg', but could not find a solution.

Any hint what I can do to fix this?

Thanks,
Holger