Re: [PATCH -v5][RFC]: mutex: implement adaptive spinning

Steven Rostedt
2009-01-08T02:33:58Z

On Wed, 7 Jan 2009, Linus Torvalds wrote:
> > Should that be:
> >
> > #if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_MEMORY_HOTPLUG)
>
> Well, probably CONFIG_MEMORY_HOTREMOVE, no? And I'd actually suggest that
> unplugging should have a stop-machine if it doesn't already, just because
> it's such a special case - like module removal.

I do not think stop-machine will help, unless that spinning is protected
by preempt-disable. If the task gets preempted after grabbing the owner
thread_info, and then stop-machine runs, the memory disappears, the task
is scheduled back, accesses the owner thread_info and then page-fault.

-- Steve