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

[Steven Rostedt]

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

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