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

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:

quoted

Paul E. McKenney Thu Dec 01 2016 - 14:39:21 EST:

quoted

quoted

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.

quoted

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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