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

From Michal Hocko <mhocko@kernel.org>
Newsgroups linux.kernel
Subject Re: INFO: rcu_sched detected stalls on CPUs/tasks with `kswapd` and `mem_cgroup_shrink_node`
Date 2016-12-02 18:10 +0100
Message-ID <sJZvs-6Fu-21@gated-at.bofh.it> (permalink)
References (5 earlier) <sJE7D-85V-33@gated-at.bofh.it> <sJE7D-85V-35@gated-at.bofh.it> <sJE7D-85V-13@gated-at.bofh.it> <sJZc5-6jb-15@gated-at.bofh.it> <sJZc5-6jb-13@gated-at.bofh.it>
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On Fri 02-12-16 08:44:08, Paul E. McKenney wrote:
> On Fri, Dec 02, 2016 at 07:39:24PM +0300, Boris Zhmurov wrote:
> > 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.
> 
> Very good!  I have these two patches queued for 4.11.

FWIW I have posted the cond_resched patch to Andrew [1]. I didn't CC you
Paul to save you from emails as this is more MM than anything else
related ;)

[1] http://lkml.kernel.org/r/20161202095841.16648-1-mhocko@kernel.org
-- 
Michal Hocko
SUSE Labs

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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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