Just wanted to confirm this bug for another HP server:

Kernel: 2.6.18-6-686 #1 SMP Fri Jun 6 22:22:11 UTC 2008 i686 GNU/Linux
Package: linux-image-2.6.18-6-686_2.6.18.dfsg.1-18etch6_i386.deb

Ifenslave: ifenslave-2.6_1.1.0-6_i386.deb

Exact same bonding config (except the IP's)

Note: The bonding works with mode: 0,2,3 but kernel panics on
balance-alb (mode 6)

The server is a HP Proliant GL360 g4 with 2 ethernet cards built-in:
eth0: Tigon3 [partno(349321-001) rev 2100 PHY(5704)] (PCIX:66MHz:64-bit)
10/100/1000BaseT Ethernet 00:11:85:5c:3e:d3
eth1: Tigon3 [partno(349321-001) rev 2100 PHY(5704)] (PCIX:66MHz:64-bit)
10/100/1000BaseT Ethernet 00:11:85:5c:3e:d2