Re: [RFC][PATCH 4/6] memcg: swap cgroup for remembering account

KAMEZAWA Hiroyuki
2008-11-12T04:23:12Z

On Wed, 12 Nov 2008 13:17:01 +0900
Daisuke Nishimura <d-nishimura@mtf.biglobe.ne.jp> wrote:

> > +/**
> > + * lookup_swap_cgroup - lookup mem_cgroup tied to swap entry
> > + * @ent: swap entry to be looked up.
> > + *
> > + * Returns pointer to mem_cgroup at success. NULL at failure.
> > + */
> > +struct mem_cgroup *lookup_swap_cgroup(swp_entry_t ent)
> > +{
> > + int type = swp_type(ent);
> > + unsigned long flags;
> > + unsigned long offset = swp_offset(ent);
> > + unsigned long idx = offset / SC_PER_PAGE;
> > + unsigned long pos = offset & SC_POS_MASK;
> > + struct swap_cgroup_ctrl *ctrl;
> > + struct page *mappage;
> > + struct swap_cgroup *sc;
> > + struct mem_cgroup *ret;
> > +
> > + if (!do_swap_account)
> > + return NULL;
> > +
> > + ctrl = &swap_cgroup_ctrl[type];
> > +
> > + mappage = ctrl->map[idx];
> > +
> > + spin_lock_irqsave(&ctrl->lock, flags);
> > + sc = kmap_atomic(mappage, KM_USER0);
> > + sc += pos;
> > + ret = sc->val;
> > + kunmap_atomic(mapppage, KM_USER0);
> s/mapppage/mappage
>
> I don't know why I didn't notice this while testing previous version.
>
Ah...kmap_atomic() doesn't check its argument if HIGHMEM=n.
and mapppage disappears by macro.

I'm now preparing x86-32 test enviroment before goint further.

Thanks,
-Kame

>
> Thanks,
> Daisuke Nishimura.
>
> > + spin_unlock_irqrestore(&ctrl->lock, flags);
> > + return ret;
> > +}
> > +