Ask Ubuntu is a question and answer site for Ubuntu users and developers. It's 100% free.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Got this on my machine. I was just browsing the web on Chrome and my computer froze. I recently just built this machine. I have a feeling it is a hardware problem... Possibly one of my parts arrived broken in some way....

    Starting anac(h)ronistic cron
Stopping anac(h)ronistic cron
Stopping cold plug devices
Stopping log initial device creation
Starting enable remaining boot-time encrypted block devices
Starting configure network device security
Starting configure virtual network devices
Starting save udev log and update rules
Stopping configure virtual network devices
Stopping save udev log and update rules
Checking battery state...
Stopping System V runlevel compatibility
Stopping enable remaining boot-time encrypted block devices

Stopping Mount filesystems on boot

91.573384] BUG: unable to handle kernel NULL pointer dereference at    (null)
91.573437] IP: [<ffffffff81313514>] strcmp+0x14/0x30
91.573470] PGD 1f7822067 PUD 1ed7a6067 PMD 0
91.573498] Oops: 0000 [#1] SMP
91.573519] CPU 3
91.573531] Modules linked in: dm_crypt bnep snd_hda_codec_realtek rfcomm bluetooth parport_pc ppdev arc4 fglrx(P) rt2800usb rt2800lib crc_ccitt rt2x00usb rt2x00lib mac0021 cfg80211 psmouse snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq snd_timer send_seq_device snd joydev mac_hid mei(C) soundcore serio_raw snd_page_alloc lp parport ses enclosure usbhid hid i915 drm_kms_helper drm i2c_algo_bit mxm_umi tg_video wmi usb_storage
91.573837] Pid: 2297, comm: update-notifier Tainted: P       C O 3.2.0-29-generic #46-Ubuntu To Be Filled By O.E.M. To Be Filled By O.E.M./Z77 Extreme4
91.573912] RIP: 0010:[<ffffffff81313514>]  [<ffffffff81313514>] strcmp+0x14/0x30
91.573954] RSP: 0018:ffff8801f83f5bb8  EFLAGS: 00010246
91.573982] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
91.574019] RDX: 0000000000000069 RSI: 0000000000000000 RDI: ffff88021adb26f8
91.574056] RBP: ffff8801f83f5bb8 R08: ffff88022f2d6e80 R09: 0000000000000000
91.574093] R10: ffff88021e7dbf00 R11: 0000000000000003 R12: ffff88021c10eb40
91.574130] R13: 0000000000000000 R14: ffff88021adb26f8 R15: ffff8801f83f5d40
91.574168] FS: 00007f958cf53940(0000) GS:ffff88022f2c0000(0000) kn1GS:0000000000000000
91.574210] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
91.574240] CR2: 0000000000000000 CR3: 000000021f6d7000 CR4: 00000000000406e0
91.574277] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
91.574314] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000000
91.574351] Process update-notifier (pid: 2297, threadinfo ffff801f83f4000, task ffff880208fe2e00)
91.574397] Stack:
91.574409]  ffff8801f83f5be8 ffffffff811ed509 ffff88021adb26c0 ffff88021b8b7020
91.574453]  ffff88021b461c60 fffffffffffffffe ffff8801f83f5c18 ffffffff811ed61f
91.574496]  ffff88021adb26c0 ffff88021b8b7020 ffff8801f83f5dc8 0000000000000001
91.574539] Call Trace:
91.574558]  [<ffffffff811ed509] sysfs_find_dirent+0x59/0x110
91.574591]  [<ffffffff811ed61f] sysfs_lookup+0x5f/0x110
91.574621]  [<ffffffff81182745] d_alloc_and_lookup+0x45/0x90
91.574654]  [<ffffffff8118fe65] ? d_lookup+0x35/0x60
91.574683]  [<ffffffff811848d2] do_lookup+0x202/0x310
91.574712]  [<ffffffff8118660c] path_lookupat+0x11c/0x750
91.574744]  [<ffffffff81318db7] ? __strncpy_from_user+0x27/0x60
91.574778]  [<ffffffff81186c71] do_path_lookup+0x31/0xc0
91.574809]  [<ffffffff81187779] user_path_at_empty+0x59/0xa0
91.574842]  [<ffffffff81187822] ? do_filp_open+0x42/0xa0
91.574872]  [<ffffffff811877d1] user_path_at+0x11/0x20
91.574902]  [<ffffffff8117c80a] vfs_fstatat+0x3a/0x70
91.574933]  [<ffffffff81161cff] ? kmem_cache_free+0x2f/0x110
91.574965]  [<ffffffff8117c85e] vfs_lstat+-x31/0x70
91.574993]  [<ffffffff8117c9fa] sys_newlstat+0x1a/0x40
91.575022]  [<ffffffff81176ee1] ? do_sys_open+0x171/0x220
91.575053]  [<ffffffff8117cb1a] ? sys_readlinkat+0x7a/0xb0
91.575086]  [<ffffffff81661ec2] system_call_fastpath+0x16/0x1b
91.575118] Code: 83 c1 01 40 84 ff 75 ef 5d c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 00 55 31 c0 48 89 e5 66 2e 0f 1f 84 00 00 00 00 00 0f b6 14 07 <3a> 14 06 75 0f 48 83 c0 01 84 d2 75 ef 31 c0 5d c3 0f 1f 00 19
91.577243] RIP  [<ffffffff81313514>] strcmp+0x14/0x30
91.579314]  RSP <ffff8801f83f5bb8>
91.581385] CR2: 0000000000000000
share|improve this question

Boot off the LiveCD and run memtest86 overnight. How much memory is in the machine, and how many sticks?

A Null pointer crash is not normal or a good thing, obviously. Just in case, try Firefox instead.

Check the CPU core temperatures in case it's a CPU overheating problem. If the machine locks up during memtest it can indicate a problem with the lowest memory registers, or a problem with the CPU itself.

Motherboards can be damaged during installation by overstressing them during installation, or you occasionally get a bad one for no apparent reason.

It's a good idea to run memtest overnight on all new builds to check for any obvious reliability problems.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.