Re: [PATCH] mm: memcontrol: reclaim and OOM kill when shrinking memory.max below usage

Vladimir Davydov
2016-03-11T09:20:03Z

On Fri, Mar 11, 2016 at 09:18:25AM +0100, Michal Hocko wrote:
> On Thu 10-03-16 15:50:14, Johannes Weiner wrote:
...
> > @@ -5037,9 +5040,36 @@ static ssize_t memory_max_write(struct kernfs_open_file *of,
> > if (err)
> > return err;
> >
> > - err = mem_cgroup_resize_limit(memcg, max);
> > - if (err)
> > - return err;
> > + xchg(&memcg->memory.limit, max);
> > +
> > + for (;;) {
> > + unsigned long nr_pages = page_counter_read(&memcg->memory);
> > +
> > + if (nr_pages <= max)
> > + break;
> > +
> > + if (signal_pending(current)) {
>
> Didn't you want fatal_signal_pending here? At least the changelog
> suggests that.

I suppose the user might want to interrupt the write by hitting CTRL-C.

Come to think of it, shouldn't we restore the old limit and return EBUSY
if we failed to reclaim enough memory?

>
> > + err = -EINTR;
> > + break;
> > + }