On Wed, Nov 06, 2013 at 04:30:05PM -0800, David Rientjes wrote:
> On Mon, 4 Nov 2013, Mel Gorman wrote:
>
> > This maybe?
> >
> > ---8<---
> > mm: memcontrol: Release css_set_lock when aborting an OOM scan
> >
> > css_task_iter_start acquires the css_set_lock and it must be released with
> > a call to css_task_iter_end. Commmit 9cbb78bb (mm, memcg: introduce own
> > oom handler to iterate only over its own threads) introduced a loop that
> > was not guaranteed to call css_task_iter_end.
> >
> > Cc: stable <sta...@vger.kernel.org>
> > Signed-off-by: Mel Gorman <mgor...@suse.de>
> >
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 5ef8929..941f67d 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -1795,6 +1795,7 @@ static void mem_cgroup_out_of_memory(struct
> > mem_cgroup *memcg, gfp_t gfp_mask,
> > mem_cgroup_iter_break(memcg, iter);
> > if (chosen)
> > put_task_struct(chosen);
> > + css_task_iter_end(&it);
> > return;
> > case OOM_SCAN_OK:
> > break;
>
> What tree is this?
>
> I'm afraid I don't understand this at all, I thought css_task_iter_end()
> was added to take over for cgroup_task_iter_end() and
> mem_cgroup_out_of_memory() was modified with 72ec7029937f ("cgroup: make
> task iterators deal with cgroup_subsys_state instead of cgroup")
> correctly. Why do we need to call css_task_iter_end() twice with your
> patch?
I screwed up, patch is broken. I'll recheck for imbalances in the
handling of css_set_lock. Sorry for the noise.
--
Mel Gorman
SUSE Labs
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