On 07/27/2017 01:15 PM, 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. Depending upon the order in which CPUs > are added/removed, we may run into problems with the content of the > cpumask used by the workqueues. This patch deals with situations where > the online cpumask for a node is a proper superset of possible cpumask > for the node. It also deals with edge cases where the order in which > CPUs are removed/added from the online cpumask may leave the set for a > node empty, and require execution by CPUs on another node. > > In these and other cases, the patch attempts to ensure that a valid, > usable cpumask is used to set up newly created pools for workqueues. > This patch provides a fix for NUMA systems which can add/subtract > processors dynamically. The patch is expected to be an intermediate > one while developers search for any underlying issues. > > [With additions to the patch provided by Tejun Hao <t...@kernel.org>] > > Signed-off-by: Michael Bringmann <m...@linux.vnet.ibm.com> > --- > Changes in V6: > -- Update descriptive text > --- > kernel/workqueue.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > index c74bf39..6b6d540 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -3577,6 +3577,13 @@ static bool wq_calc_node_cpumask(const struct > workqueue_attrs *attrs, int node, > > /* yeap, return possible CPUs in @node that @attrs wants */ > cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); > + > + if (cpumask_empty(cpumask)) { > + pr_warn_once("WARNING: workqueue cpumask: onl intersect > " ^^^ This message doesn't seem right, or I am missing something, "onl"?
-Nathan > + "possible intersect\n"); > + return false; > + } > + > return !cpumask_equal(cpumask, attrs->cpumask); > > use_dfl: >