"WARNING: Kernel Errors Present"

Maybe. What's the rest of the error? (It'll be in the log file itself.)

Feb 13 08:47:35 localhost kernel: mysqld: page allocation failure: order:5, mode:0x20 Feb 13 08:47:35 localhost kernel: Pid: 25092, comm: mysqld Not tainted 3.0.18-linode43 #1 Feb 13 08:47:35 localhost kernel: Call Trace: Feb 13 08:47:35 localhost kernel: [<c01962b8>] ? warn_alloc_failed+0x98/0x100 Feb 13 08:47:35 localhost kernel: [<c0196b40>] ? __alloc_pages_nodemask+0x410/0x680 Feb 13 08:47:35 localhost kernel: [<c01be243>] ? T.837+0xb3/0x2e0 Feb 13 08:47:35 localhost kernel: [<c01be6b6>] ? cache_alloc_refill+0x246/0x290 Feb 13 08:47:35 localhost kernel: [<c01be7bd>] ? __kmalloc+0xbd/0xd0 Feb 13 08:47:35 localhost kernel: [<c055027e>] ? pskb_expand_head+0x12e/0x210 Feb 13 08:47:35 localhost kernel: [<c05507dd>] ? __pskb_pull_tail+0x4d/0x2b0 Feb 13 08:47:35 localhost kernel: [<c061d9c3>] ? ipv4_confirm+0xf3/0x1b0 Feb 13 08:47:35 localhost kernel: [<c05591bd>] ? dev_hard_start_xmit+0x1dd/0x3e0 Feb 13 08:47:35 localhost kernel: [<c05dde70>] ? ip_finish_output2+0x260/0x260 Feb 13 08:47:35 localhost kernel: [<c05dde70>] ? ip_finish_output2+0x260/0x260 Feb 13 08:47:35 localhost kernel: [<c056d582>] ? sch_direct_xmit+0xb2/0x170 Feb 13 08:47:35 localhost kernel: [<c05594b9>] ? dev_queue_xmit+0xf9/0x320 Feb 13 08:47:35 localhost kernel: [<c05ddfab>] ? ip_finish_output+0x13b/0x300 Feb 13 08:47:35 localhost kernel: [<c05de21a>] ? ip_output+0xaa/0xe0 Feb 13 08:47:35 localhost kernel: [<c05dd3b8>] ? ip_local_out+0x18/0x20 Feb 13 08:47:35 localhost kernel: [<c05f0d85>] ? tcp_transmit_skb+0x385/0x670 Feb 13 08:47:35 localhost kernel: [<c05f37c5>] ? tcp_write_xmit+0x1e5/0x4f0 Feb 13 08:47:35 localhost kernel: [<c05f3b34>] ? __tcp_push_pending_frames+0x24/0x90 Feb 13 08:47:35 localhost kernel: [<c05efb52>] ? tcp_rcv_established+0x3d2/0x610 Feb 13 08:47:35 localhost kernel: [<c059567c>] ? nf_iterate+0x6c/0x90 Feb 13 08:47:35 localhost kernel: [<c05f666e>] ? tcp_v4_do_rcv+0xce/0x1a0 Feb 13 08:47:35 localhost kernel: [<c05f6df9>] ? tcp_v4_rcv+0x6b9/0x7a0 Feb 13 08:47:35 localhost kernel: [<c05d8df7>] ? ip_local_deliver_finish+0x97/0x220 Feb 13 08:47:35 localhost kernel: [<c05d8d60>] ? ip_rcv+0x320/0x320 Feb 13 08:47:35 localhost kernel: [<c05d87bb>] ? ip_rcv_finish+0xfb/0x380 Feb 13 08:47:35 localhost kernel: [<c055688e>] ? __netif_receive_skb+0x2fe/0x370 Feb 13 08:47:35 localhost kernel: [<c0558077>] ? netif_receive_skb+0x67/0x70 Feb 13 08:47:35 localhost kernel: [<c04f8dcc>] ? handle_incoming_queue+0x17c/0x250 Feb 13 08:47:35 localhost kernel: [<c04f90bc>] ? xennet_poll+0x21c/0x540 Feb 13 08:47:35 localhost kernel: [<c055880a>] ? net_rx_action+0xea/0x190 Feb 13 08:47:35 localhost kernel: [<c013c43c>] ? __do_softirq+0x7c/0x110 Feb 13 08:47:35 localhost kernel: [<c013c3c0>] ? irq_enter+0x60/0x60 Feb 13 08:47:35 localhost kernel: <irq> [<c0109920>] ? math_state_restore+0x50/0x50 Feb 13 08:47:35 localhost kernel: [<c013c21e>] ? irq_exit+0x6e/0xa0 Feb 13 08:47:35 localhost kernel: [<c048d96d>] ? xen_evtchn_do_upcall+0x1d/0x30 Feb 13 08:47:35 localhost kernel: [<c06d6ec7>] ? xen_do_upcall+0x7/0xc Feb 13 08:47:35 localhost kernel: [<c0109920>] ? math_state_restore+0x50/0x50 Feb 13 08:47:35 localhost kernel: [<c0101227>] ? hypercall_page+0x227/0x1000 Feb 13 08:47:35 localhost kernel: [<c0105c27>] ? xen_force_evtchn_callback+0x17/0x30 Feb 13 08:47:35 localhost kernel: [<c0109920>] ? math_state_restore+0x50/0x50 Feb 13 08:47:35 localhost kernel: [<c0106404>] ? check_events+0x8/0xc Feb 13 08:47:35 localhost kernel: [<c01063c3>] ? xen_irq_enable_direct_reloc+0x4/0x4 Feb 13 08:47:35 localhost kernel: [<c0109934>] ? do_device_not_available+0x14/0x20 [b]Feb 13 08:47:35 localhost kernel: [<c06d6676>] ? error_code+0x5a/0x60[/b] Feb 13 08:47:35 localhost kernel: [<c06d0000>] ? init_intel+0xa6/0x294 Feb 13 08:47:35 localhost kernel: [<c0109920>] ? math_state_restore+0x50/0x50 Feb 13 08:47:35 localhost kernel: Mem-Info: Feb 13 08:47:35 localhost kernel: DMA per-cpu: Feb 13 08:47:35 localhost kernel: CPU 0: hi: 0, btch: 1 usd: 0 Feb 13 08:47:35 localhost kernel: CPU 1: hi: 0, btch: 1 usd: 0 Feb 13 08:47:35 localhost kernel: CPU 2: hi: 0, btch: 1 usd: 0 Feb 13 08:47:35 localhost kernel: CPU 3: hi: 0, btch: 1 usd: 0 Feb 13 08:47:35 localhost kernel: Normal per-cpu: Feb 13 08:47:35 localhost kernel: CPU 0: hi: 186, btch: 31 usd: 37 Feb 13 08:47:35 localhost kernel: CPU 1: hi: 186, btch: 31 usd: 100 Feb 13 08:47:35 localhost kernel: CPU 2: hi: 186, btch: 31 usd: 158 Feb 13 08:47:35 localhost kernel: CPU 3: hi: 186, btch: 31 usd: 180 Feb 13 08:47:35 localhost kernel: active_anon:4021 inactive_anon:11211 isolated_anon:0 Feb 13 08:47:35 localhost kernel: active_file:48143 inactive_file:46050 isolated_file:0 Feb 13 08:47:35 localhost kernel: unevictable:0 dirty:101 writeback:0 unstable:0 Feb 13 08:47:35 localhost kernel: free:7881 slab_reclaimable:3630 slab_unreclaimable:2271 Feb 13 08:47:35 localhost kernel: mapped:3641 shmem:64 pagetables:395 bounce:0 Feb 13 08:47:35 localhost kernel: DMA free:5992kB min:84kB low:104kB high:124kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15808kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:996kB slab_unreclaimable:212kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes Feb 13 08:47:35 localhost kernel: lowmem_reserve[]: 0 500 500 500 Feb 13 08:47:35 localhost kernel: Normal free:25656kB min:2816kB low:3520kB high:4224kB active_anon:16084kB inactive_anon:44844kB active_file:192572kB inactive_file:184200kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:512064kB mlocked:0kB dirty:404kB writeback:0kB mapped:14564kB shmem:256kB slab_reclaimable:13524kB slab_unreclaimable:8872kB kernel_stack:984kB pagetables:1580kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:16 all_unreclaimable? no Feb 13 08:47:35 localhost kernel: lowmem_reserve[]: 0 0 0 0 Feb 13 08:47:35 localhost kernel: DMA: 192*4kB 137*8kB 88*16kB 37*32kB 18*64kB 1*128kB 1*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 5992kB Feb 13 08:47:35 localhost kernel: Normal: 2424*4kB 1761*8kB 94*16kB 11*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 25640kB Feb 13 08:47:35 localhost kernel: 95892 total pagecache pages Feb 13 08:47:35 localhost kernel: 1673 pages in swap cache Feb 13 08:47:35 localhost kernel: Swap cache stats: add 36736, delete 35063, find 2717305/2719935 Feb 13 08:47:35 localhost kernel: Free swap = 248284kB Feb 13 08:47:35 localhost kernel: Total swap = 262140kB Feb 13 08:47:35 localhost kernel: 133104 pages RAM Feb 13 08:47:35 localhost kernel: 0 pages HighMem Feb 13 08:47:35 localhost kernel: 6385 pages reserved Feb 13 08:47:35 localhost kernel: 66407 pages shared Feb 13 08:47:35 localhost kernel: 72263 pages non-shared</c0109920></c06d0000></c06d6676></c0109934></c01063c3></c0106404></c0109920></c0105c27></c0101227></c0109920></c06d6ec7></c048d96d></c013c21e></c0109920></irq></c013c3c0></c013c43c></c055880a></c04f90bc></c04f8dcc></c0558077></c055688e></c05d87bb></c05d8d60></c05d8df7></c05f6df9></c05f666e></c059567c></c05efb52></c05f3b34></c05f37c5></c05f0d85></c05dd3b8></c05de21a></c05ddfab></c05594b9></c056d582></c05dde70></c05dde70></c05591bd></c061d9c3></c05507dd></c055027e></c01be7bd></c01be6b6></c01be243></c0196b40></c01962b8>

Ah, that one. There's a thread on it elsewhere. It seems to be a kernel bug, and is harmless in practice. I believe setting "vm.minfreekbytes = 16384" in /etc/sysctl.conf (which essentially does 'echo 16384 > /proc/sys/vm/minfreekbytes' on boot) will get it to shut up.

That's a relief. Thanks hoopycat!