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I'm running ubuntu-server, 3.2.0-29-generic-pae. Not every time, but enough that it is reproducible, when I cp or mv a large file the kernel panics. I read that changing the scheduler sometimes helps so I'm currently using noop instead of cfq. I've run memtest with no discernible results. And run badblocks on my ide that hosts the operating system. I have two SATA 500gb hard drives attached as well. The crash that is currently documented occurred when transferring from one to the other.

I ran cat /proc/kmsg on an ssh terminal and simulated a crash on my server, giving the following results:

7t:(ul
<4>[ 7486.965231] Disabling lock debugging due to kernel taint
<0>[ 7486.965231] [Hardware Error]: CPU 1: Machine Check Exception: 4 Bank 0: b20000001040080f
<0>[ 7486.965231] [Hardware Error]: RIP !INEXACT! 00:<00000000c1018b5c>
<0>[ 7486.965231] [Hardware Error]: TSC 1649e27da970
<0>[ 7486.965231] [Hardware Error]: PROCESSOR 0:f34 TIME 1358822531 SOCKET 0 APIC 1 microcode 13
<0>[ 7486.965231] [Hardware Error]: Run the above through 'mcelog --ascii'
<0>[ 7486.965231] [Hardware Error]: CPU 0: Machine Check Exception: 4 Bank 0: b20000001040080f
<0>[ 7486.965231] [Hardware Error]: RIP !INEXACT! 00:<00000000c12b7906>
<0>[ 7486.965231] [Hardware Error]: TSC 1649e27daae0
<0>[ 7486.965231] [Hardware Error]: PROCESSOR 0:f34 TIME 1358822531 SOCKET 0 APIC 0 microcode 13
<0>[ 7486.965231] [Hardware Error]: Run the above through 'mcelog --ascii'
<0>[ 7486.965231] [Hardware Error]: Machine check: Processor context corrupt
<0>[ 7486.965231] Kernel panic - not syncing: Fatal Machine check
<4>[ 7486.965231] Pid: 0, comm: swapper/1 Tainted: G   M         3.2.0-29-generic-pae #46-Ubuntu
<4>[ 7486.965231] Call Trace:
<4>[ 7486.965231]  [<c158f812>] ? printk+0x2d/0x2f
<4>[ 7486.965231]  [<c158f6e0>] panic+0x5c/0x161
<4>[ 7486.965231]  [<c10247ef>] mce_panic.part.14+0x13f/0x170
<4>[ 7486.965231]  [<c1024872>] mce_panic+0x52/0x90
<4>[ 7486.965231]  [<c1024a18>] mce_reign+0x168/0x170
<4>[ 7486.965231]  [<c1024bb5>] mce_end+0x105/0x110
<4>[ 7486.965231]  [<c10252db>] do_machine_check+0x32b/0x4f0
<4>[ 7486.965231]  [<c1018b5c>] ? mwait_idle+0x7c/0x1d0
<4>[ 7486.965231]  [<c1024fb0>] ? mce_log+0x120/0x120
<4>[ 7486.965231]  [<c15a5e47>] error_code+0x67/0x6c
<4>[ 7486.965231]  [<c1018b5c>] ? mwait_idle+0x7c/0x1d0
<4>[ 7486.965231]  [<c1010338>] cpu_idle+0xa8/0xe0
<4>[ 7486.965231]  [<c1588923>] start_secondary+0xe8/0xed
<3>[ 7486.965231] panic occurred, switching back to text console

Thanks for you help! curios

P.S. this is my first post, so I apologize in advance for any breaks of etiquette.

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closed as off topic by fossfreedom Jan 22 '13 at 8:26

Questions on Ask Ubuntu are expected to relate to Ubuntu within the scope defined by the community. Consider editing the question or leaving comments for improvement if you believe the question can be reworded to fit within the scope. Read more about reopening questions here.If this question can be reworded to fit the rules in the help center, please edit the question.

    
Welcome to Ask Ubuntu! I recommend bugreporting this. (This question also has good info about bug reporting.) After reading that (at least the first page), you can start the bug report by running ubuntu-bug linux. I recommend reproducing the bug as soon before reporting it as possible (then reboot and report), so it's clear in the logs. This'll probably be closed as off-topic; isee the FAQ and this policy. –  Eliah Kagan Jan 22 '13 at 4:26
    
Thank you for responding Eliah! Your comment suggests that you think my problem is not specific to my set up but rather a bug within ubuntu? How can you tell? In any case, I trust you and will report following your guidance & links asap. Thank you. –  curios Jan 22 '13 at 5:08
    
Unless you're doing something well outside the ordinary realm of normal computer use (e.g., writing a "Hello world!" kernel module) or your hardware is broken, kernel panics should not happen. (Neither should program crashes, but here you have a kernel panic.) Your problem might be specific to your setup in the sense that it might be triggered by something particular to it, but that would still be a bug, and we'd still have not much ability to deal productively with it here. To be fixed, and to help others suffering from the same bug, bugs in Ubuntu must be dealt with on Launchpad. –  Eliah Kagan Jan 22 '13 at 5:44

1 Answer 1

It looks like you've lost some of the log output, but there's some data there that seems to be pertinent:

[ 7486.965231] [Hardware Error]: CPU 1: Machine Check Exception: 4 Bank 0: b20000001040080f
[ 7486.965231] [Hardware Error]: RIP !INEXACT! 00:<00000000c1018b5c>
[ 7486.965231] [Hardware Error]: TSC 1649e27da970
[ 7486.965231] [Hardware Error]: PROCESSOR 0:f34 TIME 1358822531 SOCKET 0 APIC 1 microcode 13

This indicates that a "Machine Check Exception" was reported by the processor; this is generally due hardware issues.

The error code itself (b20000001040080f) seems to indicate an error with the bus or interconnect, perhaps you have a misbehaving PCI device? Can you remove devices and re-test, to see if the results differ?

My guess would be that it's an issue involving the disk controller. To test this hypothesis, we could try to reproduce the problem with and without load on the controller:

  • Can you reproduce the problem with only disk IO, and less memory pressure?
    • Try something like: dd if=/dev/sda of=/dev/null bs=4096,
    • Or, if you have a disk device that you can overwrite: dd if=/dev/zero of=/dev/sdc bs=4096 - but note that this will erase all data on the specified device (/dev/sdc in this example).
  • Can you reproduce this without involving disk IO?
    • You mention you've tried memtest; perhaps try a userspace memory test, like memtester, and keep an eye on dmesg for any MCEs reported?

If it does seem to be only occuring when loading the disk controller, you could then try to reproduce the problem using a different PCI device. Perhaps by putting a lot of data through the network device? This may give you some data on whether the problem is in the device itself, or the bus.

Because this looks like a hardware issue, I'd avoid filing a bug until you've done some more digging.

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It's pretty common for bugs to cause machine check exceptions. (That lists packages and changelogs too; this might be a better indication of frequency.) With that said, if you can expand your answer with specifics on how to do more digging, that would be helpful! Often, though, without investigating the problem as a bug, it's very difficult to know for sure if it is one. (Thus someone else confirming a bug is built into the the process.) –  Eliah Kagan Jan 22 '13 at 7:26
    
I've added a couple of suggested 'next steps' for debugging. –  Jeremy Kerr Jan 22 '13 at 7:41
    
Thanks so much everyone! I can see now that perhaps this wasn't the place to post this question, but nevertheless I'm glad you responded. I've some great ideas. You've saved me two weeks at least in troubleshooting. –  curios Jan 23 '13 at 1:24
    
@curios: this is a perfectly suitable place to ask the question! Even though it's not necessarily a bug in Ubuntu, it's still relevant here. –  Jeremy Kerr Jan 23 '13 at 2:57

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