[RFD][PATCH] memcg: Move Usage at Task Move

[YAMAMOTO Takashi]

> I'm now considering following logic. How do you think ?
> 
> Assume: move TASK from group:CURR to group:DEST.
> 
> == move_task(TASK, CURR, DEST)
> 
> if (DEST's limit is unlimited)
> 	moving TASK
> 	return success.
> 
> usage = check_usage_of_task(TASK).
> 
> /* try to reserve enough room in destionation */
> if (try_to_reserve_enough_room(DEST, usage)) {
> 	move TASK to DEST and move pages AMAP.
> 	/* usage_of_task(TASK) can be changed while we do this.
> 	   Then, we move AMAP. */
> 	return success;
> }
> return failure.
> ==

AMAP means that you might leave some random charges in CURR?

i think that you can redirect new charges in TASK to DEST
so that usage_of_task(TASK) will not grow.

YAMAMOTO Takashi