I've been getting on a fairly regular basis the following problem on one of my servers:

------------[ cut here ]------------
kernel BUG at mm/filemap.c:128!
invalid opcode: 0000 [#1] SMP
last sysfs file: /sys/devices/virtual/block/dm-0/dm/name
Modules linked in:

Pid: 6225, comm: emerge Not tainted (2.6.32-hardened-r22 #1) Dimension 3000
EIP: 0060:[<c1055d08>] EFLAGS: 00210002 CPU: 0
EIP is at __remove_from_page_cache+0x44/0x90
EAX: 00000001 EBX: c15d1e20 ECX: c14ba700 EDX: 00000009
ESI: c6901df4 EDI: ffffffff EBP: 00000009 ESP: de1a5df8
DS: 0068 ES: 0068 FS: 00d8 GS: 0033 SS: 0068
Process emerge (pid: 6225, ti=de1a4000 task=df92ab10 task.ti=de1a4000)
Stack:
c6901df4 c15d1e20 c1055d73 c15d1e20 c6901df4 c105bc0f c15d1e20 00000000
<0> c105bcb9 c6901df4 00000009 00000009 ffffffff 00000000 0000000e 00000000
<0> c1644c20 c17bf500 c17bba40 c17bac40 c1832ba0 c184f960 c184dd00 c16b4d00
Call Trace:
[<c1055d73>] ? remove_from_page_cache+0x1f/0x26
[<c105bc0f>] ? truncate_inode_page+0x6c/0x7d
[<c105bcb9>] ? truncate_inode_pages_range+0x99/0x24a
[<c105be73>] ? truncate_inode_pages+0x9/0xc
[<c10f46e6>] ? ext4_delete_inode+0x57/0x21d
[<c10f468f>] ? ext4_delete_inode+0x0/0x21d
[<c1088c3a>] ? generic_delete_inode+0xb2/0x12e
[<c1087fe3>] ? iput+0x48/0x4a
[<c1085ddb>] ? d_kill+0x2a/0x43
[<c108644e>] ? dput+0xfc/0x104
[<c1080e31>] ? sys_renameat+0x1ca/0x22a
[<c1069972>] ? __do_munmap+0x19/0x28f
[<c1080ea2>] ? sys_rename+0x11/0x15
[<c1002bd5>] ? syscall_call+0x7/0xb
Code: ff 4e 30 ba 09 00 00 00 89 d8 e8 ce ba 00 00 8b 03 a9 00 00 10 00 74 0c ba 16 00 00 00 89 d8 e8 b9 ba 00 00 8b 43 08 85 c0 78 04 <0f> 0b eb fe f6 03 10 74 40 8b 46 40 f6 40 18 01 75 37 ba 0a 00
EIP: [<c1055d08>] __remove_from_page_cache+0x44/0x90 SS:ESP 0068:de1a5df8
---[ end trace 5a4f0450df6d364e ]---

This problem was also occurring on a straight gentoo-sources build of the kernel as well. I highly suspect that it is a hardware issue in this particular case but wanted to get any input anyone else might have on this particular error. The machine is x86 with hyperthreading using ext4 as the filesystem.

Thanks in advance,

Alunduil