Hi,

I'm seeing a similar problem on my system with frequent soft lockup messages and machine check events logged.

Distributor ID:	Ubuntu
Description:	Ubuntu 8.10
Release:	8.10
Codename:	intrepid

Errors with linux-image-2.6.27-11-server (64-bit).  It's not clear if there are specific activities triggering the bug. Rolling back to Hardy kernel (linux-image-2.6.24-23-server) seems to have addressed the problem  - no error messages in last 12 hours of heavy system activity.

System has 2 x Western Digital WDC WD10EADS-00L5B1 drives (1TB) in RAID1 config (for both root partition and swap partition).

smulcahy@dev:/var/log$ sudo mdadm --misc -D /dev/md1 
/dev/md1:
        Version : 00.90
  Creation Time : Mon Feb  9 11:59:43 2009
     Raid Level : raid1
     Array Size : 974808064 (929.65 GiB 998.20 GB)
  Used Dev Size : 974808064 (929.65 GiB 998.20 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Tue Feb 24 12:18:54 2009
          State : active
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           UUID : c8cf85b7:a96d5ddf:b32eea70:c5f0704e
         Events : 0.25

    Number   Major   Minor   RaidDevice State
       0       8        2        0      active sync   /dev/sda2
       1       8       18        1      active sync   /dev/sdb2

smulcahy@dev:/var/log$ sudo mdadm --misc -D /dev/md2
/dev/md2:
        Version : 00.90
  Creation Time : Mon Feb  9 12:29:38 2009
     Raid Level : raid1
     Array Size : 1951744 (1906.32 MiB 1998.59 MB)
  Used Dev Size : 1951744 (1906.32 MiB 1998.59 MB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 2
    Persistence : Superblock is persistent

    Update Time : Tue Feb 24 12:08:02 2009
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           UUID : 8957636b:79f79a80:9069ef6b:43c30843
         Events : 0.8

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1



Log file excerpt,

Feb 20 10:07:20 dev kernel: [933002.012531] Machine check events logged
Feb 20 11:23:39 dev kernel: [937580.632507] BUG: soft lockup - CPU#1 stuck for 61s! [kswapd1:185]
Feb 20 11:23:39 dev kernel: [937580.632507] Modules linked in: af_packet ipv6 iptable_filter ip_tables x_tables parport_pc lp parport loop joydev evdev pcspkr container isp1760 amd_rng button i2c_amd756 k8temp shpchp i2c_amd8111 pci_hotplug i2c_core ext3 jbd mbcache sr_mod cdrom pata_acpi sd_mod crc_t10dif sg usbhid hid ata_generic tg3 libphy sata_sil ohci_hcd usbcore pata_amd libata scsi_mod dock raid10 raid456 async_xor async_memcpy async_tx xor raid1 raid0 multipath linear md_mod thermal processor fan fbcon tileblit font bitblit softcursor fuse
Feb 20 11:23:39 dev kernel: [937580.632507] CPU 1:
Feb 20 11:23:39 dev kernel: [937580.632507] Modules linked in: af_packet ipv6 iptable_filter ip_tables x_tables parport_pc lp parport loop joydev evdev pcspkr container isp1760 amd_rng button i2c_amd756 k8temp shpchp i2c_amd8111 pci_hotplug i2c_core ext3 jbd mbcache sr_mod cdrom pata_acpi sd_mod crc_t10dif sg usbhid hid ata_generic tg3 libphy sata_sil ohci_hcd usbcore pata_amd libata scsi_mod dock raid10 raid456 async_xor async_memcpy async_tx xor raid1 raid0 multipath linear md_mod thermal processor fan fbcon tileblit font bitblit softcursor fuse
Feb 20 11:23:39 dev kernel: [937580.632507] Pid: 185, comm: kswapd1 Tainted: G   M      2.6.27-11-server #1
Feb 20 11:23:39 dev kernel: [937580.632507] RIP: 0010:[<ffffffff802abeb7>]  [<ffffffff802abeb7>] find_get_pages+0x77/0x110
Feb 20 11:23:39 dev kernel: [937580.632507] RSP: 0018:ffff88007d5b1bc0  EFLAGS: 00000293
Feb 20 11:23:39 dev kernel: [937580.632507] RAX: ffff880070fd4ae8 RBX: ffff88007d5b1c00 RCX: ffff880070fd4ae8
Feb 20 11:23:39 dev kernel: [937580.632507] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffe2000061b300
Feb 20 11:23:39 dev kernel: [937580.632507] RBP: 000000018031371c R08: 0000000000000000 R09: 0000000000000001
Feb 20 11:23:39 dev kernel: [937580.632507] R10: 0000000000000000 R11: 0000000000000040 R12: 0000000000000001
Feb 20 11:23:39 dev kernel: [937580.632507] R13: ffffffff802b6ba9 R14: ffffe2000061b2c0 R15: 0000000000000246
Feb 20 11:23:39 dev kernel: [937580.632507] FS:  000000004020a950(0000) GS:ffff88013f40b300(0000) knlGS:00000000f7bb56b0
Feb 20 11:23:39 dev kernel: [937580.632507] CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
Feb 20 11:23:39 dev kernel: [937580.632507] CR2: 00007fa35c00b000 CR3: 0000000000201000 CR4: 00000000000006e0
Feb 20 11:23:39 dev kernel: [937580.632507] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Feb 20 11:23:39 dev kernel: [937580.632507] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Feb 20 11:23:39 dev kernel: [937580.632507] 
Feb 20 11:23:39 dev kernel: [937580.632507] Call Trace:
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff802b6a04>] ? pagevec_lookup+0x24/0x30
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff802b825b>] ? __invalidate_mapping_pages+0x8b/0x1a0
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff802fe1dc>] ? prune_one_dentry+0x4c/0x100
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff802fe4fd>] ? __shrink_dcache_sb+0x26d/0x2b0
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff803024ae>] ? generic_forget_inode+0x4e/0x190
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff802b8380>] ? invalidate_mapping_pages+0x10/0x20
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff803022ed>] ? prune_icache+0x27d/0x290
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff8030233f>] ? shrink_icache_memory+0x3f/0x50
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff802b8d45>] ? shrink_slab+0x135/0x190
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff802bac97>] ? balance_pgdat+0x3b7/0x4c0
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff802b9120>] ? isolate_pages_global+0x0/0x50
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff802bae9e>] ? kswapd+0xfe/0x150
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff80266fd0>] ? autoremove_wake_function+0x0/0x40
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff802bada0>] ? kswapd+0x0/0x150
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff80266b9e>] ? kthread+0x4e/0x90
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff80213c99>] ? child_rip+0xa/0x11
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff80266b50>] ? kthread+0x0/0x90
Feb 20 11:23:39 dev kernel: [937580.632507]  [<ffffffff80213c8f>] ? child_rip+0x0/0x11
Feb 20 11:23:39 dev kernel: [937580.632507] 
Feb 20 11:24:44 dev kernel: [937646.122507] BUG: soft lockup - CPU#1 stuck for 61s! [kswapd1:185]
Feb 20 11:24:44 dev kernel: [937646.122507] Modules linked in: af_packet ipv6 iptable_filter ip_tables x_tables parport_pc lp parport loop joydev evdev pcspkr container isp1760 amd_rng button i2c_amd756 k8temp shpchp i2c_amd8111 pci_hotplug i2c_core ext3 jbd mbcache sr_mod cdrom pata_acpi sd_mod crc_t10dif sg usbhid hid ata_generic tg3 libphy sata_sil ohci_hcd usbcore pata_amd libata scsi_mod dock raid10 raid456 async_xor async_memcpy async_tx xor raid1 raid0 multipath linear md_mod thermal processor fan fbcon tileblit font bitblit softcursor fuse
Feb 20 11:24:44 dev kernel: [937646.122507] CPU 1:
Feb 20 11:24:44 dev kernel: [937646.122507] Modules linked in: af_packet ipv6 iptable_filter ip_tables x_tables parport_pc lp parport loop joydev evdev pcspkr container isp1760 amd_rng button i2c_amd756 k8temp shpchp i2c_amd8111 pci_hotplug i2c_core ext3 jbd mbcache sr_mod cdrom pata_acpi sd_mod crc_t10dif sg usbhid hid ata_generic tg3 libphy sata_sil ohci_hcd usbcore pata_amd libata scsi_mod dock raid10 raid456 async_xor async_memcpy async_tx xor raid1 raid0 multipath linear md_mod thermal processor fan fbcon tileblit font bitblit softcursor fuse
Feb 20 11:24:44 dev kernel: [937646.122507] Pid: 185, comm: kswapd1 Tainted: G   M      2.6.27-11-server #1
Feb 20 11:24:44 dev kernel: [937646.122507] RIP: 0010:[<ffffffff802abec0>]  [<ffffffff802abec0>] find_get_pages+0x80/0x110
Feb 20 11:24:44 dev kernel: [937646.122507] RSP: 0018:ffff88007d5b1bc0  EFLAGS: 00000246
Feb 20 11:24:44 dev kernel: [937646.122507] RAX: ffff880070fd4ae8 RBX: ffff88007d5b1c00 RCX: ffff880070fd4ae8
Feb 20 11:24:44 dev kernel: [937646.122507] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffe2000061b300
Feb 20 11:24:44 dev kernel: [937646.122507] RBP: 000000018031371c R08: 0000000000000000 R09: 0000000000000001
Feb 20 11:24:44 dev kernel: [937646.122507] R10: 0000000000000000 R11: 0000000000000040 R12: 0000000000000001
Feb 20 11:24:44 dev kernel: [937646.122507] R13: ffffffff802b6ba9 R14: ffffe2000061b2c0 R15: 0000000000000246
Feb 20 11:24:44 dev kernel: [937646.122507] FS:  000000004020a950(0000) GS:ffff88013f40b300(0000) knlGS:00000000f7bb56b0
Feb 20 11:24:44 dev kernel: [937646.122507] CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
Feb 20 11:24:44 dev kernel: [937646.122507] CR2: 00007fa35c00b000 CR3: 0000000000201000 CR4: 00000000000006e0
Feb 20 11:24:44 dev kernel: [937646.122507] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Feb 20 11:24:44 dev kernel: [937646.122507] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Feb 20 11:24:44 dev kernel: [937646.122507] 
Feb 20 11:24:44 dev kernel: [937646.122507] Call Trace:
.....