On Sun, May 21, 2017 at 08:31:47PM +0200, Thomas Gleixner wrote: > On Fri, 19 May 2017, Christoph Hellwig wrote: > > - /* Stabilize the cpumasks */ > > - get_online_cpus(); > > How is that protected against physical CPU hotplug? Physical CPU hotplug > manipulates the present mask. It does indeed seem to. Documentation/core-api/cpu_hotplug.rst claims there are no locking rules for manipulations of cpu_present_mask, maybe it needs and update to mention get/put_online_cpus() ? Or maybe I should just switch to possible_cpu mask here like a lot of code seems to do to avoid the hot plug issues, but that might be a bit of a waste.
