To concur with comment #37, I speculate that you have a slow EBS volume
or you aren't able to commit things fast enough due to your heavy I/O.
Performance of EBS volumes can vary widely. One thing to remember is
that EBS disks _ARE NETWORK ATTACHED STORAGE_, and with that comes all
the fun that network attached storage bring.

I think that you can do some tuning here and see where you get. Try setting the 
following sysctl settings (these will force uncommitted disks writes to be 
flushed sooner than later). You can play with the settings, as this is a 
delicate balance between performance and being safe.  
vm.dirty_writeback_centisecs = 300 ( force flush after three seconds )
vm.dirty_ratio = 5 ( no more 3% of memory can be dirty pages )

My hunch is that you are using at least a m1.large or c1.meduim (at the
least) and you saturating the network links used to flush the disk
writes, while at the same time pulling more information onto the
disk(s), preventing the flush from completing. The default settings  on
Maverick allow for 20% of memory and 5 seconds when flushing. Reducing
the ratios will affect your performance, but I suspect that it will
stabilize your system to make sure that everything gets to disk.

Another tactic would be use to ephemeral store as a "temp" directory --
push your data to the emphemeral storage and when it is ready for
permance, commit it to the RAIDed EBS volumes.

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https://bugs.launchpad.net/bugs/666211

Title:
  maverick on ec2 64bit ext4 deadlock

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