On Wed 26-01-11 14:06:18, Andrew Morton wrote: > On Wed, 26 Jan 2011 16:21:58 +0100 > Michal Hocko <mhocko@xxxxxxx> wrote: > > > I am sorry but the patch which added swapaccount parameter is not > > correct (we have discussed it https://lkml.org/lkml/2010/11/16/103). > > I didn't get the way how __setup parameters are handled correctly. > > The patch bellow fixes that. > > > > I am CCing stable as well because the patch got into .37 kernel. > > > > --- > > >From 144c2e8aed27d82d48217896ee1f58dbaa7f1f84 Mon Sep 17 00:00:00 2001 > > From: Michal Hocko <mhocko@xxxxxxx> > > Date: Wed, 26 Jan 2011 14:12:41 +0100 > > Subject: [PATCH] memsw: handle swapaccount kernel parameter correctly > > > > __setup based kernel command line parameters handled in > > obsolete_checksetup provides the parameter value including = (more > > precisely everything right after the parameter name) so we have to check > > for =0 resp. =1 here. If no value is given then we get an empty string > > rather then NULL. > > This doesn't provide a description of the bug which just got fixed. > > From reading the code I think the current behaviour is > > "swapaccount": works OK Not really because the original test was !s || s="1" but as I am writing in the commit message we are getting an empty string rather than NULL in no parameter value case.. So noswapaccount is actually the only thing that is working. > "noswapaccount": works OK > "swapaccount=0": doesn't do anything > "swapaccount=1": doesn't do anything > > but I might be wrong about that. Please send a changelog update to > clarify all this. Sorry for not being specific enough. What about somthing like this: --- >From 317dec3d13ef7f11e8f2699331bc32fcd6a8ea0e Mon Sep 17 00:00:00 2001 From: Michal Hocko <mhocko@xxxxxxx> Date: Wed, 26 Jan 2011 14:12:41 +0100 Subject: [PATCH] memsw: handle swapaccount kernel parameter correctly __setup based kernel command line parameters handlers which are handled in obsolete_checksetup are provided with the parameter value including = (more precisely everything right after the parameter name). This means that the current implementation of swapaccount[=1|0] doesn't work at all because if there is a value for the parameter then we are testing for "0" resp. "1" but we are getting "=0" resp. "=1" and if there is no parameter value we are getting an empty string rather than NULL. The original noswapccount parameter, which doesn't care about the value, works correctly. Signed-off-by: Michal Hocko <mhocko@xxxxxxx> --- mm/memcontrol.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index db76ef7..cea2be48 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5013,9 +5013,9 @@ struct cgroup_subsys mem_cgroup_subsys = { static int __init enable_swap_account(char *s) { /* consider enabled if no parameter or 1 is given */ - if (!s || !strcmp(s, "1")) + if (!(*s) || !strcmp(s, "=1")) really_do_swap_account = 1; - else if (!strcmp(s, "0")) + else if (!strcmp(s, "=0")) really_do_swap_account = 0; return 1; } @@ -5023,7 +5023,7 @@ __setup("swapaccount", enable_swap_account); static int __init disable_swap_account(char *s) { - enable_swap_account("0"); + enable_swap_account("=0"); return 1; } __setup("noswapaccount", disable_swap_account); -- 1.7.2.3 -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>