On Wed, 12 Oct 2022 20:34:00 -0700 Wei Wang wrote:
> > I pushed this little nugget to one affected machine via KLP:
> >
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 03ffbb255e60..c1ca369a1b77 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -7121,6 +7121,10 @@ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages,
> > return true;
> > }
> >
> > + if (gfp_mask == GFP_NOWAIT) {
> > + try_charge(memcg, gfp_mask|__GFP_NOFAIL, nr_pages);
> > + refill_stock(memcg, nr_pages);
> > + }
> > return false;
> > }
> >
> AFAICT, if you force charge by passing __GFP_NOFAIL to try_charge(),
> you should return true to tell the caller that the nr_pages is
> actually being charged.
Ack - not sure what the best thing to do is, tho. Always pass NOFAIL
in softirq?
It's not clear to me yet why doing the charge/uncharge actually helps,
perhaps try_to_free_mem_cgroup_pages() does more when NOFAIL is passed?
I'll do more digging tomorrow.
> Although I am not very sure what refill_stock() does. Does that
> "uncharge" those pages?
I think so, I copied it from mem_cgroup_uncharge_skmem().
