I'm seeing the same thing that Peter Wahlman reports. Here's the output from one of my servers:


Jan 19 16:23:13  kernel: [640271.778354] ------------[ cut here ]------------
Jan 19 16:23:13  kernel: [640271.783516] kernel BUG at /build/buildd/linux-2.6.32/kernel
/cred.c:168!
Jan 19 16:23:13  kernel: [640271.788785] invalid opcode: 0000 [#1] SMP 
Jan 19 16:23:13  kernel: [640271.794625] last sysfs file: /sys/devices/pci0000:00/0000:0
0:1c.4/0000:02:00.1/irq
Jan 19 16:23:13  kernel: [640271.806738] CPU 2 
Jan 19 16:23:13  kernel: [640271.813323] Modules linked in: nfp kvm_intel kvm bridge stp
 fbcon lp tileblit font bitblit softcursor vga16fb vgastate bnx2 power_meter parport dell_wmi shpchp 
dcdbas xfs exportfs mptsas mptscsih mptbase scsi_transport_sas
Jan 19 16:23:13  kernel: [640271.839128] Pid: 22152, comm: sudo Not tainted 2.6.32-27-se
rver #49-Ubuntu PowerEdge R310
Jan 19 16:23:13  kernel: [640271.857099] RIP: 0010:[<ffffffff8108a7ae>]  [<ffffffff8108a
7ae>] __put_cred+0x3e/0x50
Jan 19 16:23:13  kernel: [640271.877475] RSP: 0018:ffff8800b187df08  EFLAGS: 00010202
Jan 19 16:23:13  kernel: [640271.888184] RAX: 0000000000000001 RBX: ffff88010300f980 RCX
: 00000000ffffffff
Jan 19 16:23:13  kernel: [640271.911071] RDX: 00000000ffffffff RSI: ffff88010300f980 RDI
: ffff88010300f980
Jan 19 16:23:13  kernel: [640271.935858] RBP: ffff8800b187df08 R08: 0000000000000000 R09
: ffff8800b1b60040
Jan 19 16:23:13  kernel: [640271.962432] R10: 00007ffc5d188f98 R11: 0000000000000246 R12
: ffff88010300f5c0
Jan 19 16:23:13  kernel: [640271.989093] R13: ffff880232e044a0 R14: ffff88010300f980 R15
: 0000000000000001
Jan 19 16:23:13  kernel: [640272.016052] FS:  00007ffc5d7b0700(0000) GS:ffff880008e40000
(0000) knlGS:0000000000000000
Jan 19 16:23:13  kernel: [640272.043282] CS:  0010 DS: 0000 ES: 0000 CR0: 00000000800500
33
Jan 19 16:23:13  kernel: [640272.057416] CR2: 00007ffc5d710000 CR3: 00000000a334a000 CR4
: 00000000000026e0
Jan 19 16:23:13  kernel: [640272.085660] DR0: 0000000000000000 DR1: 0000000000000000 DR2
: 0000000000000000
Jan 19 16:23:13  kernel: [640272.114818] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7
: 0000000000000400
Jan 19 16:23:13  kernel: [640272.144811] Process sudo (pid: 22152, threadinfo ffff8800b1
87c000, task ffff880232e044a0)
Jan 19 16:23:13  kernel: [640272.176015] Stack:
Jan 19 16:23:13  kernel: [640272.191270]  ffff8800b187df38 ffffffff8108ae21 ffff8800b187
df38 ffff88010300f5c0
Jan 19 16:23:13  kernel: [640272.206914] <0> 0000000000000000 00000000ffffffff ffff8800b
187df78 ffffffff8107c9e6
Jan 19 16:23:13  kernel: [640272.237830] <0> ffff8800b187df78 0000000000000004 000000000
0000004 00007fff476ba6a0
Jan 19 16:23:13  kernel: [640272.283543] Call Trace:
Jan 19 16:23:13  kernel: [640272.298684]  [<ffffffff8108ae21>] commit_creds+0x121/0x1e0
Jan 19 16:23:13  kernel: [640272.313701]  [<ffffffff8107c9e6>] sys_setregid+0xe6/0x140
Jan 19 16:23:13  kernel: [640272.328061]  [<ffffffff810121b2>] system_call_fastpath+0x16
/0x1b
Jan 19 16:23:13  kernel: [640272.342596] Code: 8b 04 25 c0 cb 00 00 48 3b b8 48 04 00 00
 74 23 48 3b b8 40 04 00 00 74 16 48 83 ef 80 48 c7 c6 10 a8 08 81 e8 a4 e8 03 00 c9 c3 <0f> 0b eb fe
 0f 0b eb fe 0f 0b eb fe 66 0f 1f 44 00 00 55 48 89 
Jan 19 16:23:13  kernel: [640272.392551] RIP  [<ffffffff8108a7ae>] __put_cred+0x3e/0x50
Jan 19 16:23:13  kernel: [640272.407411]  RSP <ffff8800b187df08>
Jan 19 16:23:13  kernel: [640272.430084] ---[ end trace 05fe241944174e79 ]---


Sudo version is version 1.7.2p1, kernel version is 2.6.32-27-server running on a Dell R310 with a Xeon 3440 2.53 Ghz CPU.