[rpms/systemd] rawhide: test: work around a kernel bug in virtio/vsock

[Frantisek Sumsal <frantisek@sumsal.cz>]

            A new commit has been pushed.

            Repo   : rpms/systemd
            Branch : rawhide
            Commit : 9d4edaa576e609413cdc987e6127e5f228c62ac6
            Author : Frantisek Sumsal <frantisek@sumsal.cz>
            Date   : 2026-07-06T17:26:40+00:00
            Stats  : +8/-0 in 1 file(s)
            URL    : https://src.fedoraproject.org/rpms/systemd/c/9d4edaa576e609413cdc987e6127e5f228c62ac6?branch=rawhide

            Log:
            test: work around a kernel bug in virtio/vsock

There's a virtio/vsock bug in kernel 7.1-rc where a patch for a
potential overflow inadvertently shrunk the receive buffer's effective
size below what was configured, which eventually causes the vsock
connection to get reset with ENOBUFS, that kills the journal forwarding
over vsock:

read(7, ..., 16392): No buffer space available
Entry too big, skipped
read(8, ..., 16392): No buffer space available
Entry too big, skipped
read(12, ..., 16392): No buffer space available
Entry too big, skipped
Finishing after writing 6685 entries

This then affects other systemd components that try to write to the now
broken journal, causing them to fail as well.

Let's just bump the default vsock buffer size to work around this until
the kernel fix lands.

Pending fix: https://lore.kernel.org/netdev/20260518090656.134588-3-sgarzare@redhat.com/

[skip changelog]

---
diff --git a/plans/run-integration-tests.sh b/plans/run-integration-tests.sh
index d9edd5d..dab8525 100755
--- a/plans/run-integration-tests.sh
+++ b/plans/run-integration-tests.sh
@@ -94,6 +94,14 @@ if [[ "$NPROC" -gt 4 ]]; then
     NPROC=4
 fi
 
+# Workaround for a kernel 7.x virtio/vsock bug, where a patch for a potential overflow inadvertently shrunk
+# the receive buffer's effective size below what was configured, which eventually causes the vsock connection
+# to get reset with ENOBUFS, that kills the journal forwarding over vsock
+#
+# Pending fix: https://lore.kernel.org/netdev/20260518090656.134588-3-sgarzare@redhat.com/
+sysctl -w net.core.rmem_max=16777216
+sysctl -w net.core.wmem_max=16777216
+
 # This test is only really useful if we're building with sanitizers and takes a long time, so let's skip it
 # for now.
 export TEST_SKIP="TEST-21-DFUZZER ${TEST_SKIP:-}"