Jim Keniston [off-list ref] wrote:

+int kernel_error_event_iov(const struct iovec *iov, unsigned int nseg,
+	u32 groups)
+{
...
+
+	return netlink_broadcast(kerror_nl, skb, 0, ~0, GFP_ATOMIC);

This appears to be deadlocky when called from interrupt handlers.

netlink_broadcast() does read_lock(&nl_table_lock).  But nl_table_lock is
not an irq-safe lock.

Possibly netlink_broadcast() can be made callable from hardirq context, but
it looks to be non trivial.  The various error and delivery handlers need
to be reviewed, the kfree_skb() calls should be thought about, etc.