Issues dropping vm fs caches with kernel 3.5.2 + bcache master

Hi,

I've recently set up a software RAID5 + bcache.

I'm using kernel 3.5.2 merged with bcache master branch. I'm quite
happy with the performance but
there is an important issue. I can't drop caches. Writing any number
to /proc/sys/vm/drop_caches
makes the system hungs.

Furthermore, so far I've been unable to curb bcache's memory
consumption using the available
sysctl knobs.

Is this problem known?


-- 
Javier Marcet [off-list ref]