Re: [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

Christoph Lameter
2008-02-28T00:14:08Z

On Thu, 28 Feb 2008, Andrea Arcangeli wrote:

> > 3. Keep the refcount elevated until pages are freed in another execution
> > context.
>
> Page refcount is not enough (the mmu_notifier_release will run in
> another cpu the moment after i_mmap_lock is unlocked) but mm_users may
> prevent us to change the i_mmap_lock to a mutex, but it'll slowdown
> truncate as it'll have to drop the lock and restart the radix tree
> walk every time so a change like this better fits as a separate
> CONFIG_XPMEM IMHO.

Erm. This would also be needed by RDMA etc.

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