Hello, Michael. On Thu, May 25, 2017 at 09:55:10AM -0500, Michael Bringmann wrote: > On NUMA systems with dynamic processors, the content of the cpumask > may change over time. As new processors are added via DLPAR operations, > workqueues are created for them. This patch ensures that the pools > created for new workqueues will be initialized with a cpumask before > the first worker is created, attached, and woken up. If the mask is > not set up, then the kernel will crash when 'wakeup_process' is unable > to find a valid CPU to which to assign the new worker. > > Signed-off-by: Michael Bringmann <[email protected]> > --- > Changes in V2: > -- Only fill in empty cpumasks. > --- > kernel/workqueue.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > index c74bf39..1b16ac4 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -3366,6 +3366,9 @@ static struct worker_pool *get_unbound_pool(const > struct workqueue_attrs *attrs) > copy_workqueue_attrs(pool->attrs, attrs); > pool->node = target_node; > > + if (!cpumask_weight(pool->attrs->cpumask)) > + cpumask_copy(pool->attrs->cpumask, > cpumask_of(smp_processor_id())); > +
So, the problem is that control is reaching here with empty mask. Filling it with an arbitrary cpu id doesn't really fix the bug. I think I just messed up wq_calc_node_cpumask(). Will send a fix soon. Thanks. -- tejun
