memsw: deprecate noswapaccount kernel parameter and schedule it for removal

noswapaccount couldn't be used to control memsw for both on/off cases so
we have added swapaccount[=0|1] parameter.  This way we can turn the
feature in two ways noswapaccount resp.  swapaccount=0.  We have kept the
original noswapaccount but I think we should remove it after some time as
it just makes more command line parameters without any advantages and also
the code to handle parameters is uglier if we want both parameters.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Requested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/feature-removal-schedule.txt

@@ -603,3 +603,19 @@ Why:	The adm9240, w83792d and w83793 hardware monitoring drivers have
 Who:	Jean Delvare <khali@linux-fr.org>
 
 ----------------------------
+
+What:	noswapaccount kernel command line parameter
+When:	2.6.40
+Why:	The original implementation of memsw feature enabled by
+	CONFIG_CGROUP_MEM_RES_CTLR_SWAP could be disabled by the noswapaccount
+	kernel parameter (introduced in 2.6.29-rc1). Later on, this decision
+	turned out to be not ideal because we cannot have the feature compiled
+	in and disabled by default and let only interested to enable it
+	(e.g. general distribution kernels might need it). Therefore we have
+	added swapaccount[=0|1] parameter (introduced in 2.6.37) which provides
+	the both possibilities. If we remove noswapaccount we will have
+	less command line parameters with the same functionality and we
+	can also cleanup the parameter handling a bit ().
+Who:	Michal Hocko <mhocko@suse.cz>
+
+----------------------------

mm/memcontrol.c

@@ -5034,6 +5034,7 @@ __setup("swapaccount", enable_swap_account);
 
 static int __init disable_swap_account(char *s)
 {
+	printk_once("noswapaccount is deprecated and will be removed in 2.6.40. Use swapaccount=0 instead\n");
 	enable_swap_account("=0");
 	return 1;
 }