I may have spoken too soon.

I'm getting these:

Dec  8 10:33:52 frank kernel: [ 3732.187277] The following is only an harmless informational message.
Dec  8 10:33:52 frank kernel: [ 3732.187282] Unless you get a _continuous_flood_ of these messages it means
Dec  8 10:33:52 frank kernel: [ 3732.187286] everything is working fine. Allocations from irqs cannot be
Dec  8 10:33:52 frank kernel: [ 3732.187290] perfectly reliable and the kernel is designed to handle that.
Dec  8 10:33:52 frank kernel: [ 3732.187296] swapper: page allocation failure. order:1, mode:0x20
Dec  8 10:33:52 frank kernel: [ 3732.187303] Pid: 0, comm: swapper Not tainted 2.6.31.5-0.1-default #1
Dec  8 10:33:53 frank kernel: [ 3732.187307] Call Trace:
Dec  8 10:33:53 frank kernel: [ 3732.187323]  [<ffffffff81011749>] try_stack_unwind+0x189/0x1b0
Dec  8 10:33:53 frank kernel: [ 3732.187335]  [<ffffffff8101013d>] dump_trace+0x9d/0x330
Dec  8 10:33:53 frank kernel: [ 3732.187348]  [<ffffffff81011254>] show_trace_log_lvl+0x64/0x90
Dec  8 10:33:53 frank kernel: [ 3732.187359]  [<ffffffff810112a3>] show_trace+0x23/0x40
Dec  8 10:33:53 frank kernel: [ 3732.187376]  [<ffffffff81554378>] dump_stack+0x81/0x9e
Dec  8 10:33:53 frank kernel: [ 3732.187389]  [<ffffffff811110c2>] __alloc_pages_slowpath+0x572/0x580
Dec  8 10:33:53 frank kernel: [ 3732.187403]  [<ffffffff81111221>] __alloc_pages_nodemask+0x151/0x160
Dec  8 10:33:53 frank kernel: [ 3732.187419]  [<ffffffff8114beac>] kmem_getpages+0x6c/0x190
Dec  8 10:33:53 frank kernel: [ 3732.187431]  [<ffffffff8114cfca>] fallback_alloc+0x1ca/0x290
Dec  8 10:33:53 frank kernel: [ 3732.187442]  [<ffffffff8114cd10>] ____cache_alloc_node+0xb0/0x1a0
Dec  8 10:33:53 frank kernel: [ 3732.187457]  [<ffffffff8114c1a2>] kmem_cache_alloc_node+0xa2/0x220
Dec  8 10:33:53 frank kernel: [ 3732.187474]  [<ffffffff8114c39f>] __kmalloc_node+0x7f/0x110
Dec  8 10:33:53 frank kernel: [ 3732.187489]  [<ffffffff81461cf4>] __alloc_skb+0x84/0x1a0
Dec  8 10:33:53 frank kernel: [ 3732.187500]  [<ffffffff81462150>] __netdev_alloc_skb+0x40/0x80
Dec  8 10:33:53 frank kernel: [ 3732.187524]  [<ffffffffa011eec8>] rtl8169_rx_fill+0xc8/0x280 [r8169]
Dec  8 10:33:53 frank kernel: [ 3732.187552]  [<ffffffffa011f45c>] rtl8169_rx_interrupt+0x3dc/0x590 [r8169]
Dec  8 10:33:53 frank kernel: [ 3732.187577]  [<ffffffffa01209ea>] rtl8169_poll+0x4a/0x298 [r8169]
Dec  8 10:33:53 frank kernel: [ 3732.187609]  [<ffffffff81470b49>] net_rx_action+0x149/0x2e0
Dec  8 10:33:53 frank kernel: [ 3732.187621]  [<ffffffff81076713>] __do_softirq+0xd3/0x240
Dec  8 10:33:53 frank kernel: [ 3732.187633]  [<ffffffff8100d80c>] call_softirq+0x1c/0x30
Dec  8 10:33:53 frank kernel: [ 3732.187643]  [<ffffffff8100f8c5>] do_softirq+0xb5/0x110
Dec  8 10:33:53 frank kernel: [ 3732.187653]  [<ffffffff810763a5>] irq_exit+0xb5/0xd0
Dec  8 10:33:53 frank kernel: [ 3732.187662]  [<ffffffff8100ed1c>] do_IRQ+0x7c/0x100
Dec  8 10:33:53 frank kernel: [ 3732.187679]  [<ffffffff8100d013>] ret_from_intr+0x0/0x11
Dec  8 10:33:53 frank kernel: [ 3732.187692]  [<ffffffff81039766>] native_safe_halt+0x6/0x10
Dec  8 10:33:53 frank kernel: [ 3732.187704]  [<ffffffff810168c2>] default_idle+0x62/0x120
Dec  8 10:33:53 frank kernel: [ 3732.187715]  [<ffffffff81016a42>] c1e_idle+0xc2/0x170
Dec  8 10:33:53 frank kernel: [ 3732.187726]  [<ffffffff8100b44c>] cpu_idle+0xcc/0x120
Dec  8 10:33:53 frank kernel: [ 3732.187741]  [<ffffffff8153da49>] rest_init+0x79/0xa0
Dec  8 10:33:53 frank kernel: [ 3732.187752]  [<ffffffff819e4766>] start_kernel+0x3db/0x3f8
Dec  8 10:33:53 frank kernel: [ 3732.187768]  [<ffffffff819e370d>] x86_64_start_reservations+0x134/0x14f
Dec  8 10:33:53 frank kernel: [ 3732.187780]  [<ffffffff819e3883>] x86_64_start_kernel+0x15b/0x17e
Dec  8 10:33:53 frank kernel: [ 3732.187792] Mem-Info:
Dec  8 10:33:53 frank kernel: [ 3732.187795] Node 0 DMA per-cpu:
Dec  8 10:33:53 frank kernel: [ 3732.187801] CPU    0: hi:    0, btch:   1 usd:   0
Dec  8 10:33:53 frank kernel: [ 3732.187805] CPU    1: hi:    0, btch:   1 usd:   0
Dec  8 10:33:53 frank kernel: [ 3732.187810] CPU    2: hi:    0, btch:   1 usd:   0
Dec  8 10:33:53 frank kernel: [ 3732.187814] CPU    3: hi:    0, btch:   1 usd:   0
Dec  8 10:33:53 frank kernel: [ 3732.187818] Node 0 DMA32 per-cpu:
Dec  8 10:33:53 frank kernel: [ 3732.187823] CPU    0: hi:  186, btch:  31 usd: 182
Dec  8 10:33:53 frank kernel: [ 3732.187828] CPU    1: hi:  186, btch:  31 usd:   0
Dec  8 10:33:53 frank kernel: [ 3732.187832] CPU    2: hi:  186, btch:  31 usd:   0
Dec  8 10:33:53 frank kernel: [ 3732.187837] CPU    3: hi:  186, btch:  31 usd: 128
Dec  8 10:33:53 frank kernel: [ 3732.187845] Active_anon:28848 active_file:30703 inactive_anon:29184
Dec  8 10:33:53 frank kernel: [ 3732.187848]  inactive_file:75282 unevictable:0 dirty:14340 writeback:14482 unstable:0
Dec  8 10:33:53 frank kernel: [ 3732.187855]  free:1323 slab:11348 mapped:23693 pagetables:3764 bounce:0
Dec  8 10:33:53 frank kernel: [ 3732.187860] Node 0 DMA free:2992kB min:68kB low:84kB high:100kB active_anon:0kB inactive_anon:32kB active_file:56kB inactive_file:11904kB unevictable:0kB present:15308kB pages_scanned:0 all_unreclaimable? no
Dec  8 10:33:53 frank kernel: [ 3732.187873] lowmem_reserve[]: 0 740 740 740
Dec  8 10:33:53 frank kernel: [ 3732.187881] Node 0 DMA32 free:2300kB min:3444kB low:4304kB high:5164kB active_anon:115392kB inactive_anon:116704kB active_file:122756kB inactive_file:289224kB unevictable:0kB present:758192kB pages_scanned:0 all_unreclaimable? no
Dec  8 10:33:54 frank kernel: [ 3732.187895] lowmem_reserve[]: 0 0 0 0
Dec  8 10:33:54 frank kernel: [ 3732.187902] Node 0 DMA: 3*4kB 1*8kB 2*16kB 6*32kB 11*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 1*2048kB 0*4096kB = 2996kB
Dec  8 10:33:54 frank kernel: [ 3732.187928] Node 0 DMA32: 413*4kB 1*8kB 0*16kB 0*32kB 0*64kB 1*128kB 0*256kB 1*512kB 0*1024kB 0*2048kB 0*4096kB = 2300kB
Dec  8 10:33:54 frank kernel: [ 3732.187953] 106996 total pagecache pages
Dec  8 10:33:54 frank kernel: [ 3732.187959] 37 pages in swap cache
Dec  8 10:33:54 frank kernel: [ 3732.187964] Swap cache stats: add 149, delete 112, find 38/40
Dec  8 10:33:54 frank kernel: [ 3732.187968] Free swap  = 979420kB
Dec  8 10:33:54 frank kernel: [ 3732.187971] Total swap = 979956kB
Dec  8 10:33:54 frank kernel: [ 3732.191159] 196256 pages RAM
Dec  8 10:33:54 frank kernel: [ 3732.191159] 10398 pages reserved
Dec  8 10:33:54 frank kernel: [ 3732.191159] 178199 pages shared
Dec  8 10:33:54 frank kernel: [ 3732.191159] 78264 pages non-shared


and now this (which may or may not be related):

Dec  8 10:35:13 frank udevd[433]: worker [524] unexpectedly returned with status 0x0100
Dec  8 10:35:13 frank udevd[433]: worker [524] failed while handling '/devices/pci0000:00/0000:00:14.1/host5/target5:0:0/5:0:0:0/block/sdb'


I'll let it run, and maybe it'll hang and maybe it won't.