On Mon, May 23, 2022 at 5:25 AM Yun Lu <luyun_611@xxxxxxx> wrote: > > On 2022/5/20 下午9:52, Willem de Bruijn wrote: > > > On Fri, May 20, 2022 at 2:40 AM Yun Lu <luyun_611@xxxxxxx> wrote: > >> From: luyun <luyun@xxxxxxxxxx> > >> > >> The psock_snd test sends and recievs packets over loopback, but the > >> parameter lo.accept_local is disabled by default, this test will > >> fail with Resource temporarily unavailable: > >> sudo ./psock_snd.sh > >> dgram > >> tx: 128 > >> rx: 142 > >> ./psock_snd: recv: Resource temporarily unavailable > > I cannot reproduce this failure. > > > > Passes on a machine with accept_local 0. > > > > accept_local is defined as > > > > " > > accept_local - BOOLEAN > > Accept packets with local source addresses. In combination > > with suitable routing, this can be used to direct packets > > between two local interfaces over the wire and have them > > accepted properly. > > " > I did this test on my system(Centos 8.3 X86_64): > > [root@localhost net]# sysctl net.ipv4.conf.lo.accept_local > net.ipv4.conf.lo.accept_local = 0 > [root@localhost net]# ./psock_snd -d > tx: 128 > rx: 142 > ./psock_snd: recv: Resource temporarily unavailable > [root@localhost net]# sysctl -w net.ipv4.conf.lo.accept_local=1 > net.ipv4.conf.lo.accept_local = 1 > [root@localhost net]# ./psock_snd -d > tx: 128 > rx: 142 > rx: 100 > OK > > This failure does seem to be related to accept_local. > > Also, it's reported on Ubuntu: > https://bugs.launchpad.net/ubuntu-kernel-tests/+bug/1812618 That is an old kernel, 4.18 derived. I simply am unable to reproduce this on an upstream v4.18 or v5.18. Likely something with either the distro kernel release, or another distro feature that interacts with this. Can you try v5.18 or another clean upstream kernel? Else it requires instrumenting IN_DEV_ACCEPT_LOCAL tests to understand where this sysctl makes a meaningful change for you when running this test.
