Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and `mem_cgroup_shrink_node`

From	Boris Zhmurov <bb@kernelpanic.ru>
Newsgroups	linux.kernel
Subject	Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and `mem_cgroup_shrink_node`
Date	2016-12-02 17:50 +0100
Message-ID	<sJZc5-6jb-15@gated-at.bofh.it> (permalink)
References	(7 earlier) <sJE7D-85V-29@gated-at.bofh.it> <sJE7D-85V-31@gated-at.bofh.it> <sJE7D-85V-33@gated-at.bofh.it> <sJE7D-85V-35@gated-at.bofh.it> <sJE7D-85V-13@gated-at.bofh.it>
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Paul E. McKenney Thu Dec 01 2016 - 14:39:21 EST:

>> Well, I can confirm, that replacing cond_resched_rcu_qs in 
>> shrink_node_memcg by cond_resched also makes dmesg clean from RCU 
>> CPU stall warnings.
>> 
>> I've attached patch (just modification of Paul's patch), that
>> fixes RCU stall messages in situations, when all memory is used by
>>  couchbase/memcached + fs cache and linux starts to use swap.

> Nice! Just to double-check, could you please also test your patch
> above with these two commits from -rcu?
> 
> d2db185bfee8 ("rcu: Remove short-term CPU kicking") f8f127e738e3
> ("rcu: Add long-term CPU kicking")
> 
> Thanx, Paul


Looks like patches d2db185bfee8 and f8f127e738e3 change nothing.

With cond_resched() in shrink_node_memcg and these two patches dmesg is
clean. No any RCU CPU stall messages.

Thanks.

-- 
Boris Zhmurov
mailto: bb@kernelpanic.ru
"wget http://kernelpanic.ru/bb_public_key.pgp -O - | gpg --import"

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Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and  `mem_cgroup_shrink_node` Boris Zhmurov <bb@kernelpanic.ru> - 2016-12-01 19:20 +0100
  Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and  `mem_cgroup_shrink_node` "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-01 20:40 +0100
  Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and  `mem_cgroup_shrink_node` Michal Hocko <mhocko@kernel.org> - 2016-12-02 10:40 +0100
    Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and  `mem_cgroup_shrink_node` "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-02 15:00 +0100
  Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and  `mem_cgroup_shrink_node` "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-02 17:50 +0100
    Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and  `mem_cgroup_shrink_node` Michal Hocko <mhocko@kernel.org> - 2016-12-02 18:10 +0100
      Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and  `mem_cgroup_shrink_node` "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-12-02 18:20 +0100
  Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and  `mem_cgroup_shrink_node` Boris Zhmurov <bb@kernelpanic.ru> - 2016-12-02 17:50 +0100

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