On Thu, Mar 20, 2014 at 09:40:20PM -0700, Hugh Dickins wrote: > On Thu, 20 Mar 2014, Greg KH wrote: > > On Wed, Mar 19, 2014 at 10:59:27PM -0700, Hugh Dickins wrote: > > > On Wed, 19 Mar 2014, [email protected] wrote: > > > > > > > > The patch below does not apply to the 3.13-stable tree. > > > > If someone wants it applied there, or to any other stable or longterm > > > > tree, then please email the backport, including the original git commit > > > > id to <[email protected]>. > > > > > > > > thanks, > > > > > > > > greg k-h > > > > > > > ------------------ version for 3.13.7 ------------------ > > > > Thanks, now applied. > > Thanks for including this in the 3.13.7-stable review series, Greg. > But I notice there wasn't one in the 3.10.34-stable review series: > I now think that I should have interpreted your FAILED on 3.13 mail > as a prompt to send equivalents for the earlier releases too, sorry. > > The version for Jiri's 3.12.15 would be the same as that for 3.13.7. > > But the version for 3.10.34 (or perhaps now 3.10.35) is this below. > Yes, more differences, and the old mem_cgroup_reparent_charges line > is intentionally left in for 3.10 whereas it was removed for 3.12+: > that's because the css/cgroup iterator changed in between, it used > not to supply the root of the subtree, but nowadays it does. > > Thanks, > Hugh > > ------------------ version for 3.10.34 ------------------ > > From 4fb1a86fb5e4209a7d4426d4e586c58e9edc74ac Mon Sep 17 00:00:00 2001 > From: Filipe Brandenburger <[email protected]> > Date: Mon, 3 Mar 2014 15:38:25 -0800 > Subject: [PATCH] memcg: reparent charges of children before processing parent > > Sometimes the cleanup after memcg hierarchy testing gets stuck in > mem_cgroup_reparent_charges(), unable to bring non-kmem usage down to 0. > > There may turn out to be several causes, but a major cause is this: the > workitem to offline parent can get run before workitem to offline child; > parent's mem_cgroup_reparent_charges() circles around waiting for the > child's pages to be reparented to its lrus, but it's holding > cgroup_mutex which prevents the child from reaching its > mem_cgroup_reparent_charges(). > > Further testing showed that an ordered workqueue for cgroup_destroy_wq > is not always good enough: percpu_ref_kill_and_confirm's call_rcu_sched > stage on the way can mess up the order before reaching the workqueue. > > Instead, when offlining a memcg, call mem_cgroup_reparent_charges() on > all its children (and grandchildren, in the correct order) to have their > charges reparented first. > > Fixes: e5fca243abae ("cgroup: use a dedicated workqueue for cgroup > destruction") > Signed-off-by: Filipe Brandenburger <[email protected]> > Signed-off-by: Hugh Dickins <[email protected]> > Reviewed-by: Tejun Heo <[email protected]> > Acked-by: Michal Hocko <[email protected]> > Cc: Johannes Weiner <[email protected]> > Cc: <[email protected]> [v3.10+] > Signed-off-by: Andrew Morton <[email protected]> > Signed-off-by: Linus Torvalds <[email protected]> > > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -6326,9 +6326,23 @@ static void mem_cgroup_invalidate_reclai > static void mem_cgroup_css_offline(struct cgroup *cont) > { > struct mem_cgroup *memcg = mem_cgroup_from_cont(cont); > + struct cgroup *iter; > > mem_cgroup_invalidate_reclaim_iterators(memcg); > + > + /* > + * This requires that offlining is serialized. Right now that is > + * guaranteed because css_killed_work_fn() holds the cgroup_mutex. > + */ > + rcu_read_lock(); > + cgroup_for_each_descendant_post(iter, cont) { > + rcu_read_unlock(); > + mem_cgroup_reparent_charges(mem_cgroup_from_cont(iter)); > + rcu_read_lock(); > + } > + rcu_read_unlock(); > mem_cgroup_reparent_charges(memcg);
Is this correct? ^^^ I may be missing something, but I believe this call to mem_cgroup_reparent_charges() should be dropped (as in the original commit and in your 3.13 backport). Cheers, -- Luís > + > mem_cgroup_destroy_all_caches(memcg); > } > > -- > To unsubscribe from this list: send the line "unsubscribe stable" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
