On Fri 20-07-12 17:12:16, Johannes Weiner wrote:
> On Fri, Jul 20, 2012 at 04:38:48PM +0200, Michal Hocko wrote:
> > On Fri 20-07-12 16:16:25, Johannes Weiner wrote:
> > > On Fri, Jul 20, 2012 at 03:53:29PM +0200, Michal Hocko wrote:
> > > > On Thu 19-07-12 16:34:26, Tim Chen wrote:
> > > > [...]
> > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > > > > index 33dc256..aac5672 100644
> > > > > --- a/mm/vmscan.c
> > > > > +++ b/mm/vmscan.c
> > > > > @@ -779,6 +779,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> > > > >
> > > > > cond_resched();
> > > > >
> > > > > + mem_cgroup_uncharge_start();
> > > > > while (!list_empty(page_list)) {
> > > > > enum page_references references;
> > > > > struct address_space *mapping;
> > > >
> > > > Is this safe? We have a scheduling point few lines below. What prevents
> > > > from task move while we are in the middle of the batch?
> > >
> > > The batch is accounted in task_struct, so moving a batching task to
> > > another CPU shouldn't be a problem.
> >
> > But it could also move to a different group, right?
>
> The batch-uncharging task will remember the memcg of the first page it
> processes, then pile every subsequent page belonging to the same memcg
> on top. It doesn't matter which group the task is in.
Ahh, you are right. I have missed if (batch->memcg != memcg) at the end
of mem_cgroup_do_uncharge.
Thanks!
--
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@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>