I have a similar issue, though I've so far only seen it once. I plugged in two separate HDD's into two separate USB3 ports and neither worked. The syslog is below. Rebooting the system cleared up the issue and they both work ok afterwards. Kernel: 3.13.0-62-generic Linux Mint 17 qiana ASUS P8H61-I Motherboard Oct 7 08:41:01 server kernel: [246482.379384] usb 4-1: new SuperSpeed USB device number 2 using xhci_hcd Oct 7 08:41:01 server kernel: [246482.392411] usb 4-1: Parent hub missing LPM exit latency info. Power management will be impacted. Oct 7 08:41:03 server kernel: [246484.150227] usb 4-1: New USB device found, idVendor=174c, idProduct=5106 Oct 7 08:41:03 server kernel: [246484.150234] usb 4-1: New USB device strings: Mfr=2, Product=3, SerialNumber=1 Oct 7 08:41:03 server kernel: [246484.150237] usb 4-1: Product: AS2105 Oct 7 08:41:03 server kernel: [246484.150240] usb 4-1: Manufacturer: ASMedia Oct 7 08:41:03 server kernel: [246484.150242] usb 4-1: SerialNumber: TF755AY9KZXWGM Oct 7 08:41:03 server kernel: [246484.231617] usb-storage 4-1:1.0: USB Mass Storage device detected Oct 7 08:41:03 server kernel: [246484.231831] scsi6 : usb-storage 4-1:1.0 Oct 7 08:41:03 server kernel: [246484.232051] usbcore: registered new interface driver usb-storage Oct 7 08:41:04 server kernel: [246485.231633] scsi 6:0:0:0: Direct-Access HGST HTS 725050A7E630 GH2Z PQ: 0 ANSI: 0 Oct 7 08:41:04 server kernel: [246485.232021] sd 6:0:0:0: Attached scsi generic sg3 type 0 Oct 7 08:41:04 server kernel: [246485.232283] sd 6:0:0:0: [sdc] 976773168 512-byte logical blocks: (500 GB/465 GiB) Oct 7 08:41:04 server kernel: [246485.232674] sd 6:0:0:0: [sdc] Write Protect is off Oct 7 08:41:04 server kernel: [246485.232678] sd 6:0:0:0: [sdc] Mode Sense: 23 00 00 00 Oct 7 08:41:04 server kernel: [246485.233944] sd 6:0:0:0: [sdc] No Caching mode page found Oct 7 08:41:04 server kernel: [246485.233948] sd 6:0:0:0: [sdc] Assuming drive cache: write through Oct 7 08:41:04 server kernel: [246485.235344] sd 6:0:0:0: [sdc] No Caching mode page found Oct 7 08:41:04 server kernel: [246485.235349] sd 6:0:0:0: [sdc] Assuming drive cache: write through Oct 7 08:41:04 server kernel: [246485.271401] sdc: sdc1 Oct 7 08:41:04 server kernel: [246485.272560] sd 6:0:0:0: [sdc] No Caching mode page found Oct 7 08:41:04 server kernel: [246485.272563] sd 6:0:0:0: [sdc] Assuming drive cache: write through Oct 7 08:41:04 server kernel: [246485.272566] sd 6:0:0:0: [sdc] Attached SCSI disk Oct 7 08:41:11 server kernel: [246492.384511] usb 3-2: new high-speed USB device number 4 using xhci_hcd Oct 7 08:41:27 server kernel: [246497.388741] xhci_hcd 0000:04:00.0: Timeout while waiting for address device command Oct 7 08:41:27 server kernel: [246508.406142] usb 3-2: Device not responding to set address. Oct 7 08:41:27 server kernel: [246508.610298] usb 3-2: device not accepting address 4, error -71 Oct 7 08:41:48 server kernel: [246513.614556] xhci_hcd 0000:04:00.0: Timeout while waiting for a slot Oct 7 08:41:48 server kernel: [246524.820348] ------------[ cut here ]------------ Oct 7 08:41:48 server kernel: [246524.820356] WARNING: CPU: 0 PID: 25 at /build/linux-HLTJOz/linux-3.13.0/kernel/watchdog.c:245 watchdog_overflow_callback+0xac/0xd0() Oct 7 08:41:48 server kernel: [246524.820358] Watchdog detected hard LOCKUP on cpu 0 Oct 7 08:41:48 server kernel: [246524.820359] Modules linked in: usb_storage snd_seq_dummy cuse snd_atiixp_modem snd_via82xx_modem snd_intel8x0m snd_ac97_codec ac97_bus dm_crypt snd_hda_codec_hdmi rfcomm bnep bluetooth eeepc_wmi asus_wmi sparse_keymap snd_hda_codec_via snd_hda_intel snd_usb_audio snd_usbmidi_lib snd_hda_codec snd_hwdep binfmt_misc snd_pcm nfsd auth_rpcgss nfs_acl intel_rapl nfs lockd snd_page_alloc sunrpc fscache x86_pkg_temp_thermal snd_seq_midi intel_powerclamp snd_seq_midi_event snd_rawmidi snd_seq kvm snd_seq_device crc32_pclmul snd_timer serio_raw joydev snd lirc_xbox(OX) lirc_dev(OX) nvidia(POX) lpc_ich drm soundcore mac_hid parport_pc ppdev mei_me mei vhba(OX) shpchp wmi it87 hwmon_vid coretemp lp parport hid_generic usbhid hid psmouse video ahci r8169 libahci mii Oct 7 08:41:48 server kernel: [246524.820408] CPU: 0 PID: 25 Comm: khubd Tainted: P OX 3.13.0-62-generic #102-Ubuntu Oct 7 08:41:48 server kernel: [246524.820409] Hardware name: System manufacturer System Product Name/P8H61-I, BIOS 0605 09/30/2011 Oct 7 08:41:48 server kernel: [246524.820411] 00000000 00000000 f064fb64 c165878f f064fba4 f064fb94 c1056b3e c183e098 Oct 7 08:41:48 server kernel: [246524.820416] f064fbc0 00000019 c183e0c0 000000f5 c10e845c c10e845c c10e83b0 000000c8 Oct 7 08:41:48 server kernel: [246524.820420] f040ec00 f064fbac c1056b93 00000009 f064fba4 c183e098 f064fbc0 f064fbc4 Oct 7 08:41:48 server kernel: [246524.820425] Call Trace: Oct 7 08:41:48 server kernel: [246524.820430] [] dump_stack+0x41/0x52 Oct 7 08:41:48 server kernel: [246524.820435] [] warn_slowpath_common+0x7e/0xa0 Oct 7 08:41:48 server kernel: [246524.820438] [] ? watchdog_overflow_callback+0xac/0xd0 Oct 7 08:41:48 server kernel: [246524.820441] [] ? watchdog_overflow_callback+0xac/0xd0 Oct 7 08:41:48 server kernel: [246524.820444] [] ? restart_watchdog_hrtimer+0x50/0x50 Oct 7 08:41:48 server kernel: [246524.820447] [] warn_slowpath_fmt+0x33/0x40 Oct 7 08:41:48 server kernel: [246524.820450] [] watchdog_overflow_callback+0xac/0xd0 Oct 7 08:41:48 server kernel: [246524.820453] [] __perf_event_overflow+0xad/0x350 Oct 7 08:41:48 server kernel: [246524.820457] [] ? vsnprintf+0x193/0x3d0 Oct 7 08:41:48 server kernel: [246524.820460] [] perf_event_overflow+0x15/0x20 Oct 7 08:41:48 server kernel: [246524.820464] [] intel_pmu_handle_irq+0x214/0x410 Oct 7 08:41:48 server kernel: [246524.820468] [] ? msg_print_text+0xcd/0x190 Oct 7 08:41:48 server kernel: [246524.820472] [] ? irq_work_queue+0x5b/0xa0 Oct 7 08:41:48 server kernel: [246524.820475] [] ? console_unlock+0x287/0x460 Oct 7 08:41:48 server kernel: [246524.820479] [] perf_event_nmi_handler+0x2c/0x50 Oct 7 08:41:48 server kernel: [246524.820483] [] nmi_handle.isra.2+0x57/0x1a0 Oct 7 08:41:48 server kernel: [246524.820486] [] ? dev_vprintk_emit+0x66/0x90 Oct 7 08:41:48 server kernel: [246524.820490] [] do_nmi+0x1e7/0x3d0 Oct 7 08:41:48 server kernel: [246524.820494] [] ? del_timer_sync+0x41/0x50 Oct 7 08:41:48 server kernel: [246524.820498] [] nmi_stack_correct+0x2f/0x34 Oct 7 08:41:48 server kernel: [246524.820503] [] ? xhci_handshake+0x32/0x60 Oct 7 08:41:48 server kernel: [246524.820506] [] xhci_cancel_cmd+0x17c/0x250 Oct 7 08:41:48 server kernel: [246524.820509] [] xhci_alloc_dev+0x162/0x260 Oct 7 08:41:48 server kernel: [246524.820512] [] ? usb_alloc_dev+0x29/0x2b0 Oct 7 08:41:48 server kernel: [246524.820515] [] usb_alloc_dev+0x59/0x2b0 Oct 7 08:41:48 server kernel: [246524.820518] [] ? kobject_put+0x25/0x60 Oct 7 08:41:48 server kernel: [246524.820520] [] ? xhci_free_dev+0x121/0x130 Oct 7 08:41:48 server kernel: [246524.820524] [] hub_port_connect_change+0x35e/0xaa0 Oct 7 08:41:48 server kernel: [246524.820527] [] hub_events+0x458/0xa80 Oct 7 08:41:48 server kernel: [246524.820531] [] ? __schedule+0x358/0x770 Oct 7 08:41:48 server kernel: [246524.820534] [] ? finish_wait+0x44/0x60 Oct 7 08:41:48 server kernel: [246524.820537] [] hub_thread+0x25/0x140 Oct 7 08:41:48 server kernel: [246524.820540] [] ? prepare_to_wait_event+0xd0/0xd0 Oct 7 08:41:48 server kernel: [246524.820543] [] ? hub_events+0xa80/0xa80 Oct 7 08:41:48 server kernel: [246524.820546] [] kthread+0xa1/0xc0 Oct 7 08:41:48 server kernel: [246524.820550] [] ret_from_kernel_thread+0x1b/0x28 Oct 7 08:41:48 server kernel: [246524.820552] [] ? kthread_create_on_node+0x140/0x140 Oct 7 08:41:48 server kernel: [246524.820555] ---[ end trace a9957dfe9cb266c2 ]--- Oct 7 08:41:48 server kernel: [246524.820557] perf samples too long (6030 > 5000), lowering kernel.perf_event_max_sample_rate to 25000 Oct 7 08:41:48 server kernel: [246529.563106] xhci_hcd 0000:04:00.0: Stopped the command ring failed, maybe the host is dead Oct 7 08:41:48 server kernel: [246529.563120] xhci_hcd 0000:04:00.0: Abort command ring failed