[ Cc LTP ML ] > On Fri, Mar 20, 2026 at 12:02:24PM +0100, Petr Vorel wrote: > > Hi all,
> > there is a systemd bug [1] which causes vsock_loopback not to be autoloaded > > due > > previous loading vmw_vsock_virtio_transport in an early phase of boot. > > vmw_vsock_virtio_transport requires vmw_vsock_virtio_transport_common and > > vsock, > > vsock_loopback requires vsock. > > Reproducer: [2]. > > Proposed fix in systemd: [3] > > While I think the bug should be fixed in systemd with proposed fix [3] we'd > > like > > to know opinion of the kernel vsock developers in case there is a way to > > improve > > vsock modules autoloading. > The original idea of vsock_loopback was to be used just for > testing/debugging, so maybe even the autoloading when no other transport was > loaded wasn't a great idea, but at the time we thought it might be useful > for testing. Stefano, thanks for info. > In general, therefore, if you want to use the loopback, it's always best to > load vsock_loopback. > What use case is being affected by the fact that vsock_loopback isn't loaded > automatically? It's actually testing. Only LTP test cve-2025-21756.c [1] used it. Reported [2], fixed in systemd [3]. Of course we could call 'modprobe vsock_loopback' in the test, but now not needed as as fixed in systemd. I wonder who else uses the module. Searching in Debian's codesearch I see mostly testing code (+ now systemd :)). Kind regards, Petr [1] https://github.com/linux-test-project/ltp/blob/master/testcases/cve/cve-2025-21756.c [2] https://github.com/systemd/systemd/issues/41100 [3] https://github.com/systemd/systemd/commit/7c1075fb8ff2d3b87fa463d542e2e00ac086cbd3 [4] https://codesearch.debian.net/search?q=vsock_loopback&perpkg=1&page=1 > Thanks, > Stefano
