Pah, looks like I exceeded the lkml size limit ... resending as a 
bz2'd attatchment ... sorry.

------------------------

I thought this was specific to the -mjb tree for a while, but I can
reproduce it pretty easily on virgin 2.5.70 (but 2.5.69 didn't do
this). Andrew looked and pointed out it seems to be an i_sem (ISTR
some mention of /proc somewhere too?). Got a good sysrq+t trace out
of the virgin kernel (on 16x NUMA-Q) ... below:

Anyone got any clues as to what this might be? I'm stuck ...

Thanks,

M.