On Thu, Jun 16, 2016 at 02:45:48PM +0200, Peter Zijlstra wrote: > Subject: workqueue: Fix setting affinity of unbound worker threads > From: Peter Zijlstra <pet...@infradead.org> > Date: Thu Jun 16 14:38:42 CEST 2016 > > With commit e9d867a67fd03ccc ("sched: Allow per-cpu kernel threads to > run on online && !active"), __set_cpus_allowed_ptr() expects that only > strict per-cpu kernel threads can have affinity to an online CPU which > is not yet active. > > This assumption is currently broken in the CPU_ONLINE notification > handler for the workqueues where restore_unbound_workers_cpumask() > calls set_cpus_allowed_ptr() when the first cpu in the unbound > worker's pool->attr->cpumask comes online. Since > set_cpus_allowed_ptr() is called with pool->attr->cpumask in which > only one CPU is online which is not yet active, we get the following > WARN_ON during an CPU online operation.
Applied to wq/for-4.7-fixes. Thanks. -- tejun