compiz kernel null pointer mutex_lock

[Joseph Bylund]

First, this bug is similar a bunch of other bugs, but I wasn't sure it was identical to any of the existing ones so I hope someone else can merge it for me if it is in fact a duplicate.
Second, this appears to be a bug in either compiz or the kernel.

I'm using ubuntu 11.10 everything was up to date at the time the crash occurred.

Compiz info:
compiz:
  Installed: (none)
  Candidate: 1:0.9.6+bzr20110929-0ubuntu6
  Version table:
     1:0.9.6+bzr20110929-0ubuntu6 0
        500 http://mirror.cc.columbia.edu/pub/linux/ubuntu/archive/ oneiric-updates/main amd64 Packages
     1:0.9.6+bzr20110929-0ubuntu3 0
        500 http://mirror.cc.columbia.edu/pub/linux/ubuntu/archive/ oneiric/main amd64 Packages

Addressing what I expected to happen and what happened. I'm not actually sure, as I wasn't using the computer at the time. But best I can tell it just quit working on its own. It was displaying the screensaver at the time, glslideshow in xscreensaver, and it was making the image to display (I make a clock display in imagemagick and use glslideshow to display it), but I don't think it was doing anything else. Obviously this might be hard to reproduce. Here's what I got out of /var/log/syslog, from where it starts to look suspicious to where the log ended on that date (I hard restarted the machine a few days later).

Dec 10 06:07:43 poseidon kernel: [1032171.425641] compiz[28802]: segfault at 13460 ip 0000000000013460 sp 00007fff39726f28 error 14 in compiz[400000+7c000]
Dec 10 06:07:43 poseidon kernel: [1032171.427127] BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
Dec 10 06:07:43 poseidon kernel: [1032171.427130] IP: [<ffffffff815e8f10>] mutex_lock+0x20/0x50
Dec 10 06:07:43 poseidon kernel: [1032171.427138] PGD 0
Dec 10 06:07:43 poseidon kernel: [1032171.427139] Oops: 0002 [#1] SMP
Dec 10 06:07:43 poseidon kernel: [1032171.427142] CPU 3
Dec 10 06:07:43 poseidon kernel: [1032171.427143] Modules linked in: parport_pc ppdev nls_iso8859_1 nls_cp437 btrfs libcrc32c ufs qnx4 hfsplus hfs minix ntfs vfat msdos fat jfs xfs reiserfs joydev hidp bnep rfcomm pci_stub vboxpci vboxnetadp vboxnetflt vboxdrv vesafb zfs(P) zcommon(P) znvpair(P) zavl(P) zunicode(P) spl zlib_deflate binfmt_misc snd_hda_codec_hdmi btusb bluetooth snd_seq_midi snd_rawmidi snd_seq_midi_event snd_hda_codec_realtek snd_seq snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_timer arc4 snd_seq_device snd rt61pci crc_itu_t rt2x00pci rt2x00lib mac80211 cfg80211 soundcore snd_page_alloc serio_raw eeprom_93cx6 i7core_edac nvidia(P) edac_core mxm_wmi wmi lp parport usb_storage uas usbhid hid ahci libahci pata_jmicron
Dec 10 06:07:43 poseidon kernel: [1032171.427179]
Dec 10 06:07:43 poseidon kernel: [1032171.427182] Pid: 28802, comm: compiz Tainted: P 3.0.0-13-generic #22-Ubuntu Gigabyte Technology Co., Ltd. EX58-UD3R/EX58-UD3R
Dec 10 06:07:43 poseidon kernel: [1032171.427185] RIP: 0010:[<ffffffff815e8f10>] [<ffffffff815e8f10>] mutex_lock+0x20/0x50
Dec 10 06:07:43 poseidon kernel: [1032171.427188] RSP: 0000:ffff8801c3a03b68 EFLAGS: 00010246
Dec 10 06:07:43 poseidon kernel: [1032171.427190] RAX: 0000000000000000 RBX: 0000000000000040 RCX: ffff8801c2a69ec0
Dec 10 06:07:43 poseidon kernel: [1032171.427191] RDX: ffff8801c3a03fd8 RSI: ffff8801b5e21ee0 RDI: 0000000000000040
Dec 10 06:07:43 poseidon kernel: [1032171.427193] RBP: ffff8801c3a03b78 R08: 00007f9c9af1f000 R09: dead000000100100
Dec 10 06:07:43 poseidon kernel: [1032171.427194] R10: dead000000200200 R11: dead000000100100 R12: 0000000000000040
Dec 10 06:07:43 poseidon kernel: [1032171.427196] R13: ffff8801c2adf600 R14: 0000000000000000 R15: 0000000000000000
Dec 10 06:07:43 poseidon kernel: [1032171.427198] FS: 0000000000000000(0000) GS:ffff8801cfcc0000(0000) knlGS:0000000000000000
Dec 10 06:07:43 poseidon kernel: [1032171.427200] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Dec 10 06:07:43 poseidon kernel: [1032171.427201] CR2: 0000000000000040 CR3: 00000001b632d000 CR4: 00000000000006e0
Dec 10 06:07:43 poseidon kernel: [1032171.427203] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Dec 10 06:07:43 poseidon kernel: [1032171.427204] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Dec 10 06:07:43 poseidon kernel: [1032171.427206] Process compiz (pid: 28802, threadinfo ffff8801c3a02000, task ffff8801a19c5c80)
Dec 10 06:07:43 poseidon kernel: [1032171.427207] Stack:
Dec 10 06:07:43 poseidon kernel: [1032171.427209] ffff88019eb8c210 0000000000000040 ffff8801c3a03ba8 ffffffff81133cbf
Dec 10 06:07:43 poseidon kernel: [1032171.427211] ffff88019eb8c210 ffff88019eb8c160 0000000000000000 ffff8801c3a03c08
Dec 10 06:07:43 poseidon kernel: [1032171.427214] ffff8801c3a03bf8 ffffffff8112cdb4 ffff8801c3a03c70 00007f9c91b18000
Dec 10 06:07:43 poseidon kernel: [1032171.427216] Call Trace:
Dec 10 06:07:43 poseidon kernel: [1032171.427221] [<ffffffff81133cbf>] unlink_file_vma+0x3f/0x70
Dec 10 06:07:43 poseidon kernel: [1032171.427224] [<ffffffff8112cdb4>] free_pgtables+0xb4/0x120
Dec 10 06:07:43 poseidon kernel: [1032171.427227] [<ffffffff811363f6>] exit_mmap+0xc6/0x140
Dec 10 06:07:43 poseidon kernel: [1032171.427230] [<ffffffff8105c572>] mmput.part.21+0x42/0x130
Dec 10 06:07:43 poseidon kernel: [1032171.427232] [<ffffffff8105c689>] mmput+0x29/0x30
Dec 10 06:07:43 poseidon kernel: [1032171.427235] [<ffffffff81062eda>] exit_mm+0x12a/0x160
Dec 10 06:07:43 poseidon kernel: [1032171.427238] [<ffffffff810d86b5>] ? taskstats_exit+0x45/0x240
Dec 10 06:07:43 poseidon kernel: [1032171.427241] [<ffffffff815ea6c5>] ? _raw_spin_lock_irq+0x15/0x20
Dec 10 06:07:43 poseidon kernel: [1032171.427243] [<ffffffff8106308e>] do_exit+0x17e/0x440
Dec 10 06:07:43 poseidon kernel: [1032171.427246] [<ffffffff810634f4>] do_group_exit+0x44/0xa0
Dec 10 06:07:43 poseidon kernel: [1032171.427249] [<ffffffff8107417d>] get_signal_to_deliver+0x27d/0x3f0
Dec 10 06:07:43 poseidon kernel: [1032171.427254] [<ffffffff8100a7e6>] do_signal+0x56/0x180
Dec 10 06:07:43 poseidon kernel: [1032171.427256] [<ffffffff815d4039>] ? printk+0x51/0x53
Dec 10 06:07:43 poseidon kernel: [1032171.427260] [<ffffffff812830b3>] ? security_file_permission+0x93/0xb0
Dec 10 06:07:43 poseidon kernel: [1032171.427263] [<ffffffff81167601>] ? rw_verify_area+0x61/0xf0
Dec 10 06:07:43 poseidon kernel: [1032171.427266] [<ffffffff81167b95>] ? vfs_read+0x165/0x180
Dec 10 06:07:43 poseidon kernel: [1032171.427268] [<ffffffff8100aad5>] do_notify_resume+0x65/0x80
Dec 10 06:07:43 poseidon kernel: [1032171.427270] [<ffffffff815eaa1c>] retint_signal+0x48/0x8c
Dec 10 06:07:43 poseidon kernel: [1032171.427272] Code: 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 48 83 ec 10 48 89 5d f0 4c 89 65 f8 66 66 66 66 90 48 89 fb e8 73 f3 ff ff 48 89 df <f0> ff 0f 79 05 e8 16 03 00 00 65 48 8b 04 25 80 cd 00 00 4c 8b
Dec 10 06:07:43 poseidon kernel: [1032171.427292] RIP [<ffffffff815e8f10>] mutex_lock+0x20/0x50
Dec 10 06:07:43 poseidon kernel: [1032171.427294] RSP <ffff8801c3a03b68>
Dec 10 06:07:43 poseidon kernel: [1032171.427295] CR2: 0000000000000040
Dec 10 06:07:43 poseidon kernel: [1032171.427297] ---[ end trace e2b1d6f073ceb684 ]---
Dec 10 06:07:43 poseidon kernel: [1032171.427299] Fixing recursive fault but reboot is needed!
Dec 10 06:08:48 poseidon kernel: [1032236.205150] INFO: rcu_sched_state detected stall on CPU 4 (t=15000 jiffies)
Dec 10 06:11:48 poseidon kernel: [1032416.193266] INFO: rcu_sched_state detected stall on CPU 4 (t=60030 jiffies)
Dec 10 06:14:48 poseidon kernel: [1032596.181430] INFO: rcu_sched_state detected stall on CPU 4 (t=105060 jiffies)
Dec 10 06:17:48 poseidon kernel: [1032776.169640] INFO: rcu_sched_state detected stall on CPU 4 (t=150090 jiffies)
Dec 10 06:19:42 poseidon kernel: [1032889.685652] ------------[ cut here ]------------
Dec 10 06:19:42 poseidon kernel: [1032889.685657] kernel BUG at /build/buildd/linux-3.0.0/fs/dcache.c:736!
Dec 10 06:19:42 poseidon kernel: [1032889.685659] invalid opcode: 0000 [#2] SMP
Dec 10 06:19:42 poseidon kernel: [1032889.685662] CPU 2
Dec 10 06:19:42 poseidon kernel: [1032889.685663] Modules linked in: parport_pc ppdev nls_iso8859_1 nls_cp437 btrfs libcrc32c ufs qnx4 hfsplus hfs minix ntfs vfat msdos fat jfs xfs reiserfs joydev hidp bnep rfcomm pci_stub vboxpci vboxnetadp vboxnetflt vboxdrv vesafb zfs(P) zcommon(P) znvpair(P) zavl(P) zunicode(P) spl zlib_deflate binfmt_misc snd_hda_codec_hdmi btusb bluetooth snd_seq_midi snd_rawmidi snd_seq_midi_event snd_hda_codec_realtek snd_seq snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_timer arc4 snd_seq_device snd rt61pci crc_itu_t rt2x00pci rt2x00lib mac80211 cfg80211 soundcore snd_page_alloc serio_raw eeprom_93cx6 i7core_edac nvidia(P) edac_core mxm_wmi wmi lp parport usb_storage uas usbhid hid ahci libahci pata_jmicron
Dec 10 06:19:42 poseidon kernel: [1032889.685712]
Dec 10 06:19:42 poseidon kernel: [1032889.685715] Pid: 49, comm: kswapd0 Tainted: P D 3.0.0-13-generic #22-Ubuntu Gigabyte Technology Co., Ltd. EX58-UD3R/EX58-UD3R
Dec 10 06:19:42 poseidon kernel: [1032889.685720] RIP: 0010:[<ffffffff8117e7c5>] [<ffffffff8117e7c5>] __shrink_dcache_sb+0x195/0x1a0
Dec 10 06:19:42 poseidon kernel: [1032889.685728] RSP: 0018:ffff8801c2d31c40 EFLAGS: 00010286
Dec 10 06:19:42 poseidon kernel: [1032889.685730] RAX: 0000000000000000 RBX: ffff8801cf011400 RCX: ffff8801cf0114e0
Dec 10 06:19:42 poseidon kernel: [1032889.685732] RDX: ffff880196b62440 RSI: ffff8801c2d31cdc RDI: ffffffff81a022c0
Dec 10 06:19:42 poseidon kernel: [1032889.685734] RBP: ffff8801c2d31cb0 R08: ffff8801c2d31c68 R09: 0000000000002767
Dec 10 06:19:42 poseidon kernel: [1032889.685737] R10: 0000000000000090 R11: 0000000000000000 R12: ffff880191fc5adc
Dec 10 06:19:42 poseidon kernel: [1032889.685739] R13: ffff8801cf0114e0 R14: 0000000000000008 R15: 000000000000000b
Dec 10 06:19:42 poseidon kernel: [1032889.685741] FS: 000000000Dec 13 23:09:40 poseidon kernel: imklog 5.8.1, log source = /proc/kmsg started.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

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[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Andrey Andreev (andyceo)]

I faced with something similar..

Here is my related dmesg output:

[ 723.041613] show_signal_msg: 15 callbacks suppressed
[ 723.041621] compiz[10514]: segfault at 71 ip 00007f11c6eb0565 sp 00007fff84340770 error 4 in libunityshell.so[7f11c6db4000+225000]
[ 902.798182] compiz[14654]: segfault at 0 ip (null) sp 00007fff26d67b08 error 14 in compiz[400000+7c000]
[ 969.040926] compiz[14789]: segfault at f8 ip 00007fc6ecd4e56c sp 00007fff8772c4d0 error 4 in libunityshell.so[7fc6ecc52000+225000]