I had the following happen last night while running while running Con's 
Interbench. Looking back through my log, I do see one other case where 
the same BUG triggered from running updatedb (2.6.12-RT-V0.7.51-31), but 
it didn't have all of the ext3 errors that followed this one. I really 
don't have any idea if this is a problem with RT or upstream.

Dell Precision 620 or 630
Dual 933 w/ 512MB ram

[kr@porky ~]$ /sbin/lspci
00:00.0 Host bridge: Intel Corp. 82840 840 (Carmel) Chipset Host Bridge 
(Hub A)(rev 02)
00:01.0 PCI bridge: Intel Corp. 82840 840 (Carmel) Chipset AGP Bridge 
(rev 02)
00:02.0 PCI bridge: Intel Corp. 82840 840 (Carmel) Chipset PCI Bridge 
(Hub B) (rev 02)
00:1e.0 PCI bridge: Intel Corp. 82801AA PCI Bridge (rev 02)
00:1f.0 ISA bridge: Intel Corp. 82801AA ISA Bridge (LPC) (rev 02)
00:1f.1 IDE interface: Intel Corp. 82801AA IDE (rev 02)
00:1f.2 USB Controller: Intel Corp. 82801AA USB (rev 02)
00:1f.3 SMBus: Intel Corp. 82801AA SMBus (rev 02)
01:00.0 VGA compatible controller: nVidia Corporation NV10GL [Quadro] 
(rev 10)
02:1f.0 PCI bridge: Intel Corp. 82806AA PCI64 Hub PCI Bridge (rev 03)
03:00.0 PIC: Intel Corp. 82806AA PCI64 Hub Advanced Programmable 
Interrupt Controller (rev 01)
04:04.0 Multimedia audio controller: Cirrus Logic CS 4614/22/24 
[CrystalClear SoundFusion Audio Accelerator] (rev 01)
04:05.0 SCSI storage controller: Adaptec AIC-7899P U160/m (rev 01)
04:05.1 SCSI storage controller: Adaptec AIC-7899P U160/m (rev 01)
04:0a.0 Ethernet controller: Digital Equipment Corporation DECchip 21140 
[FasterNet] (rev 20)

#######################################
Relevant portion of the log:

Jul 19 23:16:34 porky kernel: (         pdflush-81   |#1): new 62 us 
maximum-latency wakeup.
Jul 19 23:16:34 porky kernel: (      interbench-5583 |#1): new 76 us 
maximum-latency wakeup.
Jul 19 23:16:34 porky kernel: VFS: brelse: Trying to free free buffer
Jul 19 23:16:34 porky kernel: swapper/0[CPU#0]: BUG in __brelse at 
fs/buffer.c:1295
Jul 19 23:16:34 porky kernel:  [<c0104143>] dump_stack+0x23/0x30 (20)
Jul 19 23:16:34 porky kernel:  [<c011f03b>] __WARN_ON+0x6b/0x90 (52)
Jul 19 23:16:34 porky kernel:  [<c016f86a>] __brelse+0x4a/0x50 (20)
Jul 19 23:16:34 porky kernel:  [<c016fcaf>] invalidate_bh_lru+0x3f/0x80 (20)
Jul 19 23:16:34 porky kernel:  [<c0110688>] 
smp_call_function_interrupt+0x48/0x70 (24)
Jul 19 23:16:34 porky kernel:  [<c0103c2c>] 
call_function_interrupt+0x1c/0x24 (60)
Jul 19 23:16:34 porky kernel:  [<c0100da2>] cpu_idle+0x62/0xe0 (40)
Jul 19 23:16:34 porky kernel:  [<c045cab6>] start_kernel+0x1a6/0x220 (32)
Jul 19 23:16:34 porky kernel:  [<c010020e>] 0xc010020e (1099694095)
Jul 19 23:16:34 porky kernel: ---------------------------
Jul 19 23:16:34 porky kernel: | preempt count: 00010003 ]
Jul 19 23:16:34 porky kernel: | 3-level deep critical section nesting:
Jul 19 23:16:34 porky kernel: ----------------------------------------
Jul 19 23:16:34 porky kernel: .. [<c013fa8c>] .... 
add_preempt_count+0x1c/0x20
Jul 19 23:16:34 porky kernel: .....[<c016fc89>] ..   ( <= 
invalidate_bh_lru+0x19/0x80)
Jul 19 23:16:34 porky kernel: .. [<c013fa8c>] .... 
add_preempt_count+0x1c/0x20
Jul 19 23:16:34 porky kernel: .....[<c011eff7>] ..   ( <= 
__WARN_ON+0x27/0x90)
Jul 19 23:16:34 porky kernel: .. [<c013fa8c>] .... 
add_preempt_count+0x1c/0x20
Jul 19 23:16:34 porky kernel: .....[<c0140b8b>] ..   ( <= 
print_traces+0x1b/0x50)
Jul 19 23:16:34 porky kernel:
Jul 19 23:16:34 porky kernel: ------------------------------
Jul 19 23:16:34 porky kernel: | showing all locks held by: |  (swapper/0 
[c037fe80, 140]):
Jul 19 23:16:34 porky kernel: ------------------------------
Jul 19 23:16:34 porky kernel:
Jul 19 23:16:34 porky kernel: EXT3-fs error (device sdb1): 
ext3_free_blocks_sb: bit already cleared for block 1440927
Jul 19 23:16:34 porky kernel: Aborting journal on device sdb1.
Jul 19 23:16:34 porky kernel: EXT3-fs error (device sdb1): 
ext3_free_blocks_sb: bit already cleared for block 1440928
Jul 19 23:16:34 porky kernel: EXT3-fs error (device sdb1): 
ext3_free_blocks_sb: bit already cleared for block 1440929
Jul 19 23:16:34 porky kernel: EXT3-fs error (device sdb1): 
ext3_free_blocks_sb: bit already cleared for block 1440930

<snip repetative>

Jul 19 23:17:03 porky kernel: EXT3-fs error (device sdb1) in 
ext3_free_blocks_sb: Journal has aborted
Jul 19 23:17:03 porky kernel: EXT3-fs error (device sdb1) in 
ext3_free_blocks_sb: Journal has aborted
Jul 19 23:17:03 porky kernel: EXT3-fs error (device sdb1) in 
ext3_reserve_inode_write: Journal has aborted
Jul 19 23:17:03 porky kernel: EXT3-fs error (device sdb1) in 
ext3_truncate: Journal has aborted
Jul 19 23:17:03 porky kernel: EXT3-fs error (device sdb1) in 
ext3_reserve_inode_write: Journal has aborted
Jul 19 23:17:03 porky kernel: EXT3-fs error (device sdb1) in 
ext3_orphan_del: Journal has aborted
Jul 19 23:17:03 porky kernel: EXT3-fs error (device sdb1) in 
ext3_reserve_inode_write: Journal has aborted



-- 
    kr