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I have out-of-the box Debian Lenny with non-custom kernel 2.6.26-2-amd64. Brand new server that is used to 5% of it's potential, CPU and Disk-wise. Meaning it probably not crashing because of overload.

every few days it freezes with hundreds of these messages in console log:

: [284847.828428] INFO: task apache2:12473 blocked for more than 120 seconds.
: [284847.868468] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
: [284847.912759] apache2       D ffff8101bc6b7ab0     0 12473  14358
: [284847.912763]  ffff810160d5bc50 0000000000000082 ffff8101c0002e40 0000000000000000
: [284847.912766]  ffff8101a7c42950 ffff810327d92810 ffff8101a7c42bd8 0000000400000044
: [284847.912770]  ffff8101c0002e40 00000000000612d0 0000000000000000 00000040000612d0
: [284847.912773] Call Trace:
: [284847.912786]  [<ffffffff80429b0d>] __mutex_lock_slowpath+0x64/0x9b
: [284847.912790]  [<ffffffff80429972>] mutex_lock+0xa/0xb
: [284847.912794]  [<ffffffff802a20b9>] do_lookup+0x82/0x1c1
: [284847.912800]  [<ffffffff802a4271>] __link_path_walk+0x87a/0xd19
: [284847.912805]  [<ffffffff80295844>] kmem_getpages+0x96/0x15f
: [284847.912808]  [<ffffffff80295fb7>] ____cache_alloc_node+0x6d/0x106
: [284847.912814]  [<ffffffff802a4756>] path_walk+0x46/0x8b
: [284847.912819]  [<ffffffff802a4a82>] do_path_lookup+0x158/0x1cf
: [284847.912822]  [<ffffffff802a3879>] getname+0x140/0x1a7
: [284847.912827]  [<ffffffff802a53f1>] __user_walk_fd+0x37/0x4c
: [284847.912831]  [<ffffffff8029e381>] vfs_lstat_fd+0x18/0x47
: [284847.912840]  [<ffffffff8029e3c9>] sys_newlstat+0x19/0x31
: [284847.912848]  [<ffffffff8020beda>] system_call_after_swapgs+0x8a/0x8f

Almost all traces has __mutex_lock_slowpath as top-level.

Only some has different trace:

: [284847.737386] INFO: task apache2:12472 blocked for more than 120 seconds.
: [284847.777551] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
: [284847.824881] apache2       D ffff8101bc6b7ab0     0 12472  14358
: [284847.824886]  ffff8101b9cc1c50 0000000000000086 ffffffffa0131e0a 0000000000000002
: [284847.824889]  ffff8102e7454300 ffff810324c6cad0 ffff8102e7454588 0000000000000000
: [284847.824893]  0000000000000001 0000000000000296 0000000000000003 ffff8101b9cc1c58
: [284847.824896] Call Trace:
: [284847.828403]  [<ffffffffa0131e0a>] :ext3:__ext3_journal_dirty_metadata+0x1e/0x46
: [284847.828412]  [<ffffffff80429b0d>] __mutex_lock_slowpath+0x64/0x9b
: [284847.828418]  [<ffffffff80429972>] mutex_lock+0xa/0xb
: [284847.828421]  [<ffffffff802a20b9>] do_lookup+0x82/0x1c1
: [284847.828427]  [<ffffffff802a4271>] __link_path_walk+0x87a/0xd19
: [284847.828428]  [<ffffffff80271296>] find_lock_page+0x1f/0x8a
: [284847.828428]  [<ffffffff80273182>] filemap_fault+0x1c2/0x33c
: [284847.828428]  [<ffffffff802a4756>] path_walk+0x46/0x8b
: [284847.828428]  [<ffffffff802a4a82>] do_path_lookup+0x158/0x1cf
: [284847.828428]  [<ffffffff802a3879>] getname+0x140/0x1a7
: [284847.828428]  [<ffffffff802a53f1>] __user_walk_fd+0x37/0x4c
: [284847.828428]  [<ffffffff8029e381>] vfs_lstat_fd+0x18/0x47
: [284847.828428]  [<ffffffff8029e3c9>] sys_newlstat+0x19/0x31
: [284847.828428]  [<ffffffff8020beda>] system_call_after_swapgs+0x8a/0x8f
 kernel: [1912668.466347] INFO: task apache2:17984 blocked for more than 120 seconds.
  [1912668.507035] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
: [1912668.555165] apache2       D ffff8101c5637ba0     0 17984  17282
: [1912668.596752]  ffff810166a7dd30 0000000000000086 0000000000000000 ffff810166a7dcd8
: [1912668.643341]  ffff8101c563c880 ffff81024505f000 0000000000000002 ffff810166a7dd68
: [1912668.699566]  0000000000000086 00000000000cb1a0 0000000000000000 ffff81017f344d60
: [1912668.744773] Call Trace:
: [1912668.761754]  [<ffffffff8022a3ed>] pick_next_task_fair+0x6e/0x7a
: [1912668.829311]  [<ffffffff802be0e2>] bio_alloc_bioset+0x89/0xd9
: [1912668.861930]  [<ffffffff8024ac3a>] getnstimeofday+0x39/0x98
: [1912668.897005]  [<ffffffff802710f6>] sync_page+0x0/0x41
: [1912668.927868]  [<ffffffff80429487>] io_schedule+0x5c/0x9e
: [1912668.960286]  [<ffffffff80271132>] sync_page+0x3c/0x41
: [1912668.991756]  [<ffffffff804295fa>] __wait_on_bit_lock+0x36/0x66
: [1912669.031757]  [<ffffffff802710e3>] __lock_page+0x5e/0x64
: [1912669.064191]  [<ffffffff802461d3>] wake_bit_function+0x0/0x23
: [1912669.100100]  [<ffffffff80281bc5>] handle_mm_fault+0x5e4/0x8de
: [1912669.134531]  [<ffffffff802461a5>] autoremove_wake_function+0x0/0x2e
: [1912669.174623]  [<ffffffff802aa108>] fcntl_setlk+0x1cf/0x291
: [1912669.210623]  [<ffffffff802461a5>] autoremove_wake_function+0x0/0x2e
: [1912669.246923]  [<ffffffff802a677f>] sys_fcntl+0x280/0x2f7

After googling for "mutex_lock_slowpath" I can only find the Kernel mailing list discussions that this issue was introduced in some commit. Wthout reference to verison. Discussions as recent as Jan 25, 2011. The Kernel I am using is form Debian Lenny, year ago.

What should I do? Is this bug even fixed in kernel? if it's such obvious bug why it happens so rarely?

  • Should I download latest kernel from kernel.org and upgrade?
  • Should I use Debian backports to install new "Approved" kernel?

Am I missing something? What to do?

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2 Answers 2

Are you using an SSD drive by any chance?

I've seen these errors on my Ubuntu 10.10 system. What would happen was that there would be a SATA glitch that would completely mess up the disk subsystem. Subsequent attempts at disk I/O would result in 120-second timeouts similar to yours (the stack trace varied.)

I've documented the original problem here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/707583

The (somewhat lame) question I asked about the timeouts is here: Mystery stack traces in /var/log/messages

I was using a P55-based motherboard and Crucial SSD drives. However, I've seen this reported with other chipsets, other makes of SSD drives, and other Linux kernels.

As far as I can tell, the only thing in common was the use of SSD drives.

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I am using Adaptec RAID controller –  Roddick Feb 24 '11 at 7:22
    
I would carefully look through the logs to see if there's any evidence of disk trouble before these messages show up. In my case these were caused by a very specific problem with the disk subsystem. Fixing the root cause made the timeouts go away. –  NPE Feb 25 '11 at 11:37
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I saw that problem in one or two of my servers some time ago (Ubuntu 8.0.4 LTS). I would recommend the following:

  • Check that you don't have any hardware issue (in my case, there was disks and potentially memory issues)
  • Check the load (CPU, IOs, memory, swap)
  • Consider upgrading your Linux kernel (2.6.26 is pretty old)
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