memcg: fix account leak at failure of memsw acconting

memcg: fix account leak at failure of memsw acconting

Commit 4b53433468 ("memcg: clean up try_charge main loop") removes a
cancel of charge at case: memory charge-> success.  mem+swap charge->
failure.

This leaks usage of memory.  Fix it.

Signed-off-by: KAMEZAWA Hiroyuki <[email protected]>
Reviewed-by: Johannes Weiner <[email protected]>
Acked-by: Daisuke Nishimura <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: <[email protected]>	[2.6.36+]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>