Merge branch 'vsock-virtio-fix-skb-overhead-accounting-to-preserve-full-buf_alloc'

Merge branch 'vsock-virtio-fix-skb-overhead-accounting-to-preserve-full-buf_alloc'

Stefano Garzarella says:

====================
vsock/virtio: fix skb overhead accounting to preserve full buf_alloc

Patch 1 resets the connection when we can no longer queue packets,
this prevents silent data loss, and both peers are notified.

Patch 2 increases the total budget to `buf_alloc * 2` for payload
plus skb overhead similar to how SO_RCVBUF is doubled to reserve
space for sk_buff metadata. This preserves the full buf_alloc for
payload under normal operation, while still bounding the skb queue
growth.

In the future, we plan to improve how we handle the merging of packets
to minimize overhead and avoid closing connections.

v3: https://lore.kernel.org/netdev/20260513105417.56761-1-sgarzare@redhat.com/
v2: https://lore.kernel.org/netdev/20260512080737.36787-1-sgarzare@redhat.com/
v1: https://lore.kernel.org/netdev/20260508092330.69690-1-sgarzare@redhat.com/
====================

Link: https://patch.msgid.link/20260518090656.134588-1-sgarzare@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>