Re: [PATCH] mmu notifiers #v5

[Christoph Lameter]

On Thu, 31 Jan 2008, Robin Holt wrote:

> > Mutex locking? Could you be more specific?
> 
> I think he is talking about the external locking that xpmem will need
> to do to ensure we are not able to refault pages inside of regions that
> are undergoing recall/page table clearing.  At least that has been my
> understanding to this point.

Right this has to be something like rw spinlock. Its needed for both 
GRU/XPmem. Not sure about KVM.

Take the read lock for invalidate operations. These can occur 
concurrently. (Or a simpler implementation for the GRU may just use a 
spinlock).

The write lock must be held for populate operations.

Lock can be refined as needed by the notifier driver. F.e. locking could 
be restricted to certain ranges.

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