> > Hi, > there were multiple reportes of the similar RCU stalls. Only Boris has > confirmed that this patch helps in his workload. Others might see a > slightly different issue and that should be investigated if it is the > case. As pointed out by Paul [1] cond_resched might be not sufficient > to silence RCU stalls because that would require a real scheduling. > This is a separate problem, though, and Paul is working with Peter [2] > to resolve it. > > Anyway, I believe that this patch should be a good start because it > really seems that nr_taken=0 during the LRU isolation can be triggered > in the real life. All reporters are agreeing to start seeing this issue > when moving on to 4.8 kernel which might be just a coincidence or a > different behavior of some subsystem. Well, MM has moved from zone to > node reclaim but I couldn't have found any direct relation to that > change. > > [1] http://lkml.kernel.org/r/[email protected] > [2] http://lkml.kernel.org/r/[email protected] > > mm/vmscan.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index c05f00042430..c4abf08861d2 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2362,6 +2362,8 @@ static void shrink_node_memcg(struct pglist_data > *pgdat, struct mem_cgroup *memc > } > } > > + cond_resched(); > +
I see a cond_resched_rcu_qs() as a part of linux next inside the while (nr[..]) loop. Do we need this as well? Balbir Singh.
