I copied two files from a USB flash drive plugged into one of the two USB 2.0 ports, unmounted it and got the following error as I unplugged it (I didn't experience this error before): [10019.724987] usb 2-1.1: new high-speed USB device number 5 using ehci_hcd [10019.839068] scsi7 : usb-storage 2-1.1:1.0 [10020.836416] scsi 7:0:0:0: Direct-Access USB DISK 2.0 PMAP PQ: 0 ANSI: 0 CCS [10020.837364] sd 7:0:0:0: Attached scsi generic sg4 type 0 [10021.868949] sd 7:0:0:0: [sdd] 2007040 512-byte logical blocks: (1.02 GB/980 MiB) [10021.869528] sd 7:0:0:0: [sdd] Write Protect is off [10021.869533] sd 7:0:0:0: [sdd] Mode Sense: 23 00 00 00 [10021.870042] sd 7:0:0:0: [sdd] No Caching mode page present [10021.870048] sd 7:0:0:0: [sdd] Assuming drive cache: write through [10021.872521] sd 7:0:0:0: [sdd] No Caching mode page present [10021.872526] sd 7:0:0:0: [sdd] Assuming drive cache: write through [10021.873372] sdd: sdd1 [10021.875263] sd 7:0:0:0: [sdd] No Caching mode page present [10021.875267] sd 7:0:0:0: [sdd] Assuming drive cache: write through [10021.875270] sd 7:0:0:0: [sdd] Attached SCSI removable disk [10145.623944] usb 2-1.1: USB disconnect, device number 5 [10145.624621] scsi 7:0:0:0: killing request [10145.624708] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 [10145.624764] IP: [<ffffffff814a8409>] sd_revalidate_disk+0x39/0x1d00 [10145.624803] PGD 1e0f23067 PUD 1e0f24067 PMD 0 [10145.624844] Oops: 0000 [#1] SMP [10145.624880] CPU 1 [10145.624900] Modules linked in: vboxpci(O) vboxnetadp(O) vboxnetflt(O) vboxdrv(O) radeon ttm iwlwifi r8169 [10145.625018] [10145.625039] Pid: 2140, comm: udisks-daemon Tainted: G W O 3.3.0-rc7-custom #1 Hewlett-Packard HP Pavilion dv7 Notebook PC/3389 [10145.625154] RIP: 0010:[<ffffffff814a8409>] [<ffffffff814a8409>] sd_revalidate_disk+0x39/0x1d00 [10145.625237] RSP: 0018:ffff8801e0f41a38 EFLAGS: 00010246 [10145.625286] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88013c84a280 [10145.625349] RDX: 0000000000000005 RSI: 0000000000000002 RDI: ffff88024bab5000 [10145.625413] RBP: ffff8801e0f41af8 R08: 0000000800000000 R09: 00000008ffffffff [10145.625476] R10: 0000000000000001 R11: 0000000000000000 R12: ffff88024bab5000 [10145.625542] R13: 00000000ffffff85 R14: ffff880251438698 R15: ffff88024bab5000 [10145.625607] FS: 00007f564b9637c0(0000) GS:ffff88025fa40000(0000) knlGS:0000000000000000 [10145.625679] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [10145.625732] CR2: 0000000000000008 CR3: 00000001e0f22000 CR4: 00000000000406e0 [10145.625797] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [10145.625861] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [10145.625927] Process udisks-daemon (pid: 2140, threadinfo ffff8801e0f40000, task ffff8802518d5a80) [10145.625982] Stack: [10145.626001] ffff8801e0f41a88 ffffffff8117e04a ffffffff814671bf ffffffff81198db0 [10145.626060] ffff8801e0f41a98 ffff88024bab5048 0000000000000000 00000000ffffff85 [10145.626106] ffff8801e0f41aa8 ffffffff81166b98 ffff88024bab5000 ffff880251438760 [10145.626151] Call Trace: [10145.626171] [<ffffffff8117e04a>] ? iget5_locked+0x9a/0x1e0 [10145.626203] [<ffffffff814671bf>] ? device_release+0x2f/0xa0 [10145.626235] [<ffffffff81198db0>] ? bdev_test+0x20/0x20 [10145.626264] [<ffffffff81166b98>] ? get_super+0x28/0xd0 [10145.626293] [<ffffffff8117d948>] ? iput+0x48/0x210 [10145.626322] [<ffffffff8132081a>] rescan_partitions+0xaa/0x2d0 [10145.626355] [<ffffffff8119a71e>] __blkdev_get+0x2de/0x440 [10145.626385] [<ffffffff8131365a>] ? freed_request+0x4a/0x70 [10145.626416] [<ffffffff8119a8d3>] blkdev_get+0x53/0x300 [10145.626445] [<ffffffff8119abdd>] blkdev_open+0x5d/0x80 [10145.626475] [<ffffffff81161cd0>] __dentry_open+0x290/0x360 [10145.626505] [<ffffffff8119ab80>] ? blkdev_get+0x300/0x300 [10145.626536] [<ffffffff811703d0>] ? do_lookup+0x50/0x3d0 [10145.626576] [<ffffffff81163161>] nameidata_to_filp+0x71/0x80 [10145.628254] [<ffffffff81172d8c>] do_last+0x26c/0x910 [10145.629929] [<ffffffff81173543>] path_openat+0xd3/0x3c0 [10145.631425] [<ffffffff81827575>] ? __slab_free+0xea/0x23f [10145.633154] [<ffffffff81488044>] ? scsi_device_put+0x44/0x60 [10145.634236] [<ffffffff81173952>] do_filp_open+0x42/0xa0 [10145.635155] [<ffffffff8117fd8f>] ? alloc_fd+0x4f/0x150 [10145.636078] [<ffffffff81163268>] do_sys_open+0xf8/0x1d0 [10145.636994] [<ffffffff81163361>] sys_open+0x21/0x30 [10145.637880] [<ffffffff818382d2>] system_call_fastpath+0x16/0x1b [10145.638749] Code: 81 ec 98 00 00 00 66 66 66 66 90 48 8b 9f 48 03 00 00 65 48 8b 04 25 28 00 00 00 48 89 45 c8 31 c0 8b 05 db eb e6 00 48 89 7d 90 <4c> 8b 7b 08 c1 e8 15 83 e0 07 83 f8 03 0f 87 7a 1b 00 00 41 8b [10145.640785] RIP [<ffffffff814a8409>] sd_revalidate_disk+0x39/0x1d00 [10145.641773] RSP <ffff8801e0f41a38> [10145.642715] CR2: 0000000000000008 [10145.711076] ---[ end trace a7919e7f17c0a727 ]---
I just tried to reproduce the bug several times and with the other USB ports, but it didn't work out.
It should have been fixed between v3.3-rc7 and v3.3 by commit fe316bf2d5847bc5dd975668671a7b1067603bc7 and 9f53d2fe815b4011ff930a7b6db98385d45faa68.
*** This bug has been marked as a duplicate of bug 42783 ***