Hi, This has just happened to me with -rc7-git1 while trying to use a not sufficiently powered external disk (we should survive that IMO): usb 6-3: new high speed USB device using ehci_hcd and address 9 usb 6-3: device descriptor read/64, error -110 usb 6-3: device descriptor read/64, error -110 usb 6-3: new high speed USB device using ehci_hcd and address 10 usb 6-3: device descriptor read/64, error -110 usb 6-3: device descriptor read/64, error -110 usb 6-3: new high speed USB device using ehci_hcd and address 11 usb 6-3: device not accepting address 11, error -110 usb 6-3: new high speed USB device using ehci_hcd and address 12 usb 6-3: device not accepting address 12, error -110 hub 6-0:1.0: unable to enumerate USB device on port 3 usb 2-1: new full speed USB device using ohci_hcd and address 2 usb 2-1: not running at top speed; connect to a high speed hub usb 2-1: configuration #1 chosen from 1 choice usb 2-1: New USB device found, idVendor=04cf, idProduct=8818 usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 usb 2-1: Product: USB Mass Storage Device usb 2-1: Manufacturer: Myson Century, Inc. usb 2-1: SerialNumber: 100 Initializing USB Mass Storage driver... scsi12 : SCSI emulation for USB Mass Storage devices usb-storage: device found at 2 usb-storage: waiting for device to settle before scanning usbcore: registered new interface driver usb-storage USB Mass Storage support registered. scsi 12:0:0:0: Direct-Access IC25N060 ATMR04-0 MO3O PQ: 0 ANSI: 0 CCS sd 12:0:0:0: [sdc] 117210240 512-byte hardware sectors (60012 MB) sd 12:0:0:0: [sdc] Write Protect is off sd 12:0:0:0: [sdc] Mode Sense: 00 14 00 00 sd 12:0:0:0: [sdc] Assuming drive cache: write through sd 12:0:0:0: [sdc] 117210240 512-byte hardware sectors (60012 MB) sd 12:0:0:0: [sdc] Write Protect is off sd 12:0:0:0: [sdc] Mode Sense: 00 14 00 00 sd 12:0:0:0: [sdc] Assuming drive cache: write through sdc:<6>usb 2-1: USB disconnect, address 2 sd 12:0:0:0: [sdc] Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 0 Buffer I/O error on device sdc, logical block 0 sd 12:0:0:0: [sdc] Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 0 Buffer I/O error on device sdc, logical block 0 unable to read partition table sd 12:0:0:0: [sdc] Attached SCSI disk sd 12:0:0:0: Attached scsi generic sg3 type 0 BUG: unable to handle kernel NULL pointer dereference at 0000000000000004 IP: [<ffffffffa038e6f1>] :usb_storage:slave_alloc+0x41/0x80 PGD 1260ff067 PUD 119076067 PMD 0 Oops: 0000 [1] SMP CPU 3 Modules linked in: usb_storage parport_pc lp parport usblp nfsd lockd auth_rpcgss sunrpc exportfs iptable_filter ip_tables ip6table_filter ip6_tables x_tables ipv6 cpufreq_conservative cpufreq_ondemand cpufreq_userspace cpufreq_powersave powernow_k8 freq_table snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device reiserfs dm_mod ohci1394 sr_mod cdrom floppy ieee1394 serio_raw rtc_cmos sky2 wmi snd_hda_intel rtc_core sg rtc_lib joydev snd_pcm snd_timer snd_page_alloc snd_hwdep snd evdev button soundcore raid456 async_xor async_memcpy async_tx xor raid0 usbhid ff_memless ehci_hcd ohci_hcd sd_mod edd raid1 ext3 jbd fan pata_marvell pata_atiixp thermal processor Pid: 9319, comm: usb-stor-scan Not tainted 2.6.26-rc7 #196 RIP: 0010:[<ffffffffa038e6f1>] [<ffffffffa038e6f1>] :usb_storage:slave_alloc+0x41/0x80 RSP: 0018:ffff8100a20cdb60 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff810087d828d0 RCX: 0000000000000003 RDX: ffff8101275f08e0 RSI: ffff810086cc49d0 RDI: ffff810124144b90 RBP: ffff8100a20cdb70 R08: 0000000000000001 R09: 0000000000000000 R10: ffffffff807fe7e0 R11: 0000000000000000 R12: ffff810087499000 R13: ffff810124953678 R14: ffff810087d82000 R15: 0000000000000000 FS: 00007f22f6561700(0000) GS:ffff810127c997c0(0000) knlGS:00000000eeb1db90 CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b CR2: 0000000000000004 CR3: 0000000122089000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process usb-stor-scan (pid: 9319, threadinfo ffff8100a20cc000, task ffff810086cc4300) Stack: ffff810087499000 ffff810124953650 ffff8100a20cdbb0 ffffffff803ea940 ffff8100a20cdbb0 ffff810087d82000 0000000000000000 0000000000000000 ffff810124953678 0000000000000000 ffff8100a20cdcf0 ffffffff803eac9a Call Trace: [<ffffffff803ea940>] scsi_alloc_sdev+0x1e0/0x250 [<ffffffff803eac9a>] scsi_probe_and_add_lun+0x12a/0xc20 [<ffffffff803ebd4f>] __scsi_scan_target+0x3bf/0x6c0 [<ffffffff8025db46>] ? mark_held_locks+0x56/0xa0 [<ffffffff804ebbe9>] ? mutex_lock_nested+0x1b9/0x290 [<ffffffff8025dcdf>] ? trace_hardirqs_on+0xbf/0x150 [<ffffffff803ec0da>] scsi_scan_channel+0x8a/0xa0 [<ffffffff803ec1e8>] scsi_scan_host_selected+0xf8/0x160 [<ffffffff803ec2ce>] do_scsi_scan_host+0x7e/0x80 [<ffffffff803ec850>] scsi_scan_host+0x190/0x1d0 [<ffffffffa0390f3d>] :usb_storage:usb_stor_scan_thread+0x6d/0x1c0 [<ffffffff8024f790>] ? autoremove_wake_function+0x0/0x40 [<ffffffffa0390ed0>] ? :usb_storage:usb_stor_scan_thread+0x0/0x1c0 [<ffffffff8024f33d>] kthread+0x4d/0x80 [<ffffffff8020c608>] child_rip+0xa/0x12 [<ffffffff8020bd1f>] ? restore_args+0x0/0x30 [<ffffffff8024f2f0>] ? kthread+0x0/0x80 [<ffffffff8020c5fe>] ? child_rip+0x0/0x12 Code: 1f c6 87 c3 00 00 00 24 48 8b 7f 08 48 81 c3 d0 08 00 00 8b 83 9c 00 00 00 48 8b 53 78 c1 e8 0f 83 e0 0f 48 8b 84 c2 e8 03 00 00 <0f> b7 70 04 ff ce e8 44 d9 fb df 80 bb c4 00 00 00 04 75 12 49 RIP [<ffffffffa038e6f1>] :usb_storage:slave_alloc+0x41/0x80 RSP <ffff8100a20cdb60> CR2: 0000000000000004 ---[ end trace 2077f860f94c5bf3 ]--- sd 12:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 0 Buffer I/O error on device sdc, logical block 0 Buffer I/O error on device sdc, logical block 1 Buffer I/O error on device sdc, logical block 2 Buffer I/O error on device sdc, logical block 3 sd 12:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 0 Buffer I/O error on device sdc, logical block 0 sd 12:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 117210112 Buffer I/O error on device sdc, logical block 14651264 sd 12:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 117210112 Buffer I/O error on device sdc, logical block 14651264 sd 12:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 117210112 Buffer I/O error on device sdc, logical block 14651264 sd 12:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 0 sd 12:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 0 sd 12:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 0 sd 12:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK end_request: I/O error, dev sdc, sector 117210232 It resulted in usb-storage being unusable and a system reboot. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html