On Wed, 14 Apr 2010 10:40:10 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> On Wed, 14 Apr 2010 10:03:08 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
>
> > > > @@ -2563,6 +2565,15 @@ void mem_cgroup_end_migration(struct mem
> > > > */
> > > > if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
> > > > mem_cgroup_uncharge_page(target);
> > > > + else {
> > > > + /*
> > > > + * When a migrated file cache is remapped, it's not charged.
> > > > + * Verify it. Because we're under lock_page(), there are
> > > > + * no race with uncharge.
> > > > + */
> > > > + if (page_mapped(target))
> > > > + mem_cgroup_update_file_mapped(mem, target, 1);
> > > > + }
> > > We cannot rely on page lock, because when we succeeded in page migration,
> > > "target" = "newpage" has already unlocked in move_to_new_page(). So the "target"
> > > can be removed from the radix-tree theoretically(it's not related to this
> > > underflow problem, though).
> > > Shouldn't we call lock_page(target) and check "if (!target->mapping)" to handle
> > > this case(maybe in another patch) ?
> > >
> > Sounds reasonable. I think about that.
> >
>
Thinking again....new page is unlocked here. It means the new page may be
removed from radix-tree before commit_charge().
Haha, it seems totally wrong. please wait..
Thanks,
-Kame
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>