Hello,

On Tue, Aug 29, 2017 at 03:33:25PM +0200, Michal Hocko wrote:

Hmm, we have this in should_reclaim_retry
			/*
			 * Memory allocation/reclaim might be called from a WQ
			 * context and the current implementation of the WQ
			 * concurrency control doesn't recognize that
			 * a particular WQ is congested if the worker thread is
			 * looping without ever sleeping. Therefore we have to
			 * do a short sleep here rather than calling
			 * cond_resched().
			 */
			if (current->flags & PF_WQ_WORKER)
				schedule_timeout_uninterruptible(1);

And I thought it would be susfficient for kworkers for concurrency WQ
congestion thingy to jump in. Or do we need something more generic. E.g.
make cond_resched special for kworkers?

I actually think we're hitting a bug somewhere.  Tetsuo's trace with
the patch applies doesn't add up.

Thanks.

-- 
tejun

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