Dom0 Xen kernel crashes in the netloop module on Red Hat Enterprise Linux 5.7 or later

Issue

The dom0 kernel of a Xen host may crash with the following (or similar) stack trace in the netloop module:

Unable to handle kernel paging request at ffff8800238a05c0
RIP: [<ffffffff8873c208>] :netloop:loopback_start_xmit+0x123/0x2ea
PGD 105d067 PUD 105e067 PMD 117b067 PTE 0
[...]
Call Trace:
 <IRQ>  [<ffffffff80424b6d>] dev_hard_start_xmit+0x1b7/0x28a
 [<ffffffff80230b81>] dev_queue_xmit+0x31f/0x3ef
 [<ffffffff80233073>] ip_output+0x29a/0x2dd
 [<ffffffff80235783>] ip_queue_xmit+0x42c/0x486
 [<ffffffff8021d32d>] __mod_timer+0xff/0x10e
 [<ffffffff802d269e>] __kmalloc+0x8f/0x9f
 [<ffffffff80222ad2>] tcp_transmit_skb+0x646/0x67e
 [<ffffffff802341b7>] __tcp_push_pending_frames+0x75d/0x849
 [<ffffffff8021c647>] tcp_rcv_established+0x818/0x8bd
 [<ffffffff8023cc5a>] tcp_v4_do_rcv+0x2a/0x2fa
 [<ffffffff8022c1ce>] local_bh_enable+0x9/0x9c
 [<ffffffff8878e164>] :ip_conntrack:ip_confirm+0x33/0x39
 [<ffffffff80227cbe>] tcp_v4_rcv+0xa23/0xa77
 [<ffffffff8044076c>] ip_local_deliver_finish+0x0/0x1eb
 [<ffffffff80258542>] nf_hook_slow+0x58/0xbc
 [<ffffffff8044076c>] ip_local_deliver_finish+0x0/0x1eb
 [<ffffffff8023597c>] ip_local_deliver+0x19f/0x265
 [<ffffffff80236cdc>] ip_rcv+0x539/0x57c
 [<ffffffff80221590>] netif_receive_skb+0x495/0x4c4
 [<ffffffff802319a4>] process_backlog+0x9b/0x104
 [<ffffffff8020d0a1>] net_rx_action+0xb4/0x1c6
 [<ffffffff80212f06>] __do_softirq+0x8d/0x13b
 [<ffffffff8025fda4>] call_softirq+0x1c/0x278
 [<ffffffff8026db69>] do_softirq+0x31/0x90
 [<ffffffff8025f8d6>] do_hypervisor_callback+0x1e/0x2c
 <EOI>  [<ffffffff802063aa>] hypercall_page+0x3aa/0x1000
 [<ffffffff802063aa>] hypercall_page+0x3aa/0x1000
 [<ffffffff8026efa8>] raw_safe_halt+0x87/0xab
 [<ffffffff8026c553>] xen_idle+0x38/0x4a
 [<ffffffff8024ac15>] cpu_idle+0x97/0xba
 [<ffffffff80758b11>] start_kernel+0x21f/0x224
 [<ffffffff807581e5>] _sinittext+0x1e5/0x1eb