Re: [PATCH] memcg: fix hotplugged memory zone oops

Michal Hocko
2012-11-03T07:00:06Z

On Fri 02-11-12 16:37:37, Hugh Dickins wrote:
> On Fri, 2 Nov 2012, Michal Hocko wrote:
> > On Fri 02-11-12 11:21:59, Michal Hocko wrote:
> > > On Thu 01-11-12 18:28:02, Hugh Dickins wrote:
> > [...]
> >
> > And I forgot to mention that the following hunk will clash with
> > "memcg: Simplify mem_cgroup_force_empty_list error handling" which is in
> > linux-next already (via Tejun's tree).
>
> Oh, via Tejun's tree. Right, when I checked mmotm there was no problem.

Yeah, whole that thing goes through Tejun's tree because there are many
follow up clean ups depending on that change.

> > Would it be easier to split the patch into the real fix and the hunk
> > bellow? That one doesn't have to go into stable anyway and we would save
> > some merging conflicts. The updated fix on top of -mm tree is bellow for
> > your convinience.
>
> I'd prefer to leave it as one patch, so even the "future proof" part
> of the fix goes into 3.7 and stable. But your point is that you have
> already seen the future, and it forks in a slightly different direction!
>
> Well, I don't want to be obstructive, but it doesn't look difficult
> to resolve.

True.

> Perhaps if I hold off on splitting them, and see if akpm barks at me
> or not :)
>
> Hugh
>
> > > > /**
> > > > @@ -3688,17 +3712,17 @@ unsigned long mem_cgroup_soft_limit_recl
> > > > static bool mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
> > > > int node, int zid, enum lru_list lru)
> > > > {
> > > > - struct mem_cgroup_per_zone *mz;
> > > > + struct lruvec *lruvec;
> > > > unsigned long flags, loop;
> > > > struct list_head *list;
> > > > struct page *busy;
> > > > struct zone *zone;
> > > >
> > > > zone = &NODE_DATA(node)->node_zones[zid];
> > > > - mz = mem_cgroup_zoneinfo(memcg, node, zid);
> > > > - list = &mz->lruvec.lists[lru];
> > > > + lruvec = mem_cgroup_zone_lruvec(zone, memcg);
> > > > + list = &lruvec->lists[lru];
> > > >
> > > > - loop = mz->lru_size[lru];
> > > > + loop = mem_cgroup_get_lru_size(lruvec, lru);
> > > > /* give some margin against EBUSY etc...*/
> > > > loop += 256;
> > > > busy = NULL;

--
Michal Hocko
SUSE Labs