kit memory use ...

[Michael Meeks]

Hi Gabriel,

	As discussed, this is a fun one =)

	We have to open the /proc/self/smaps file just after we fork the 
loolkit worker, and just before we drop capabilities - cf. kit/Kit.cpp.

	Any attempts to open it after that, or from wsd will not succeed due to 
kernel paranoia: fair enough.

	In a unipoll world - we could have a second local thread to read that 
data from the kit and send it to wsd / Admin code.

	But - that's painful around making our existing (rather pleasant) 
single-threaded, easy to reason about lock-free poll loop far more complex.

	The approach I'd love to see here is a simpler one:

	* we pass the fd across the unix socket the kit has
	  to WSD using:

https://stackoverflow.com/questions/28003921/sending-file-descriptor-by-linux-socket?answertab=votes#tab-top

	* then move the memory polling magic from the Kit
  	  process to the Admin socket poll - which is where
	  it belongs. Then we can kill bad guys based
	  on policy from the Admin poll.

	That should be beautiful, simplify the IPC logging we have 
significantly, make logs shorter, cleaner, and prettier.

	And life should be cleaner & prettier =)

	Sounds good ?

		Michael.

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