On Thu, Jul 27, 2017 at 04:27:14PM -0500, Michael Bringmann wrote: > > There is an underlying assumption/trade-off in many layers of the Linux > system that CPU <-> node mapping is static. This is despite the presence > of features like NUMA and 'hotplug' that support the dynamic addition/ > removal of fundamental system resources like CPUs and memory. PowerPC > systems, however, do provide extensive features for the dynamic change > of resources available to a system. > > Currently, there is little or no synchronization protection around the > updating of the CPU <-> node mapping, and the export/update of this > information for other layers / modules. In systems which can change > this mapping during 'hotplug', like PowerPC, the information is changing > underneath all layers that might reference it. > > This patch attempts to ensure that a valid, usable cpumask attribute is > used by the workqueue infrastructure when setting up new resource pools. > It prevents a crash that has been observed when an 'empty' cpumask is > passed along to the worker/task scheduling code. It is intended as an > intermediate fix until a more fundamental review and correction of the > issue can be done. > > [With additions to the patch provided by Tejun Hao <t...@kernel.org>] > > Signed-off-by: Michael Bringmann <m...@linux.vnet.ibm.com>
Applied to wq/for-4.13-fixes with "fix" replaced with "workaround". Thanks. -- tejun
