On Tue, Feb 07, 2017 at 10:42:49AM +0000, Mel Gorman wrote: > On Tue, Feb 07, 2017 at 10:23:31AM +0100, Vlastimil Babka wrote: > > > cpu offlining. I have to check the code but my impression was that WQ > > > code will ignore the cpu requested by the work item when the cpu is > > > going offline. If the offline happens while the worker function already > > > executes then it has to wait as we run with preemption disabled so we > > > should be safe here. Or am I missing something obvious? > > > > Tejun suggested an alternative solution to avoiding get_online_cpus() in > > this thread: > > https://lkml.kernel.org/r/<20170123170329.GA7820@xxxxxxxxxxxxxxx> > > But it would look like the following as it could be serialised against > pcpu_drain_mutex as the cpu hotplug teardown callback is allowed to sleep. > Bah, this is obviously unsafe. It's guaranteed to deadlock. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
