Commit 6fec10a1 authored Jul 22, 2012 by Tejun Heo

workqueue: fix spurious CPU locality WARN from process_one_work()



25511a47 "workqueue: reimplement CPU online rebinding to handle idle
workers" added CPU locality sanity check in process_one_work().  It
triggers if a worker is executing on a different CPU without UNBOUND
or REBIND set.

This works for all normal workers but rescuers can trigger this
spuriously when they're serving the unbound or a disassociated
global_cwq - rescuers don't have either flag set and thus its
gcwq->cpu can be a different value including %WORK_CPU_UNBOUND.

Fix it by additionally testing %GCWQ_DISASSOCIATED.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
LKML-Refence: <20120721213656.GA7783@linux.vnet.ibm.com>

parent 46f3d976

kernel/workqueue.c

+6 −0

Original line number	Original line	Diff line number	Diff line
	@@ -1949,7 +1949,13 @@ __acquires(&gcwq->lock)

	lockdep_copy_map(&lockdep_map, &work->lockdep_map);		lockdep_copy_map(&lockdep_map, &work->lockdep_map);
	#endif		#endif
			/*
			* Ensure we're on the correct CPU. DISASSOCIATED test is
			* necessary to avoid spurious warnings from rescuers servicing the
			* unbound or a disassociated gcwq.
			*/
	WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND \| WORKER_REBIND)) &&		WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND \| WORKER_REBIND)) &&
			!(gcwq->flags & GCWQ_DISASSOCIATED) &&
	raw_smp_processor_id() != gcwq->cpu);		raw_smp_processor_id() != gcwq->cpu);

	/*		/*