[ofa-general] Re: [PATCH 01 of 12] Core of mmu notifiers

[Christoph Lameter]

On Wed, 23 Apr 2008, Andrea Arcangeli wrote:

> The only way to avoid failing because of vmalloc space shortage or
> oom, would be to provide a O(N*N) fallback. But one that can't be
> interrupted by sigkill! sigkill interruption was ok in #v12 because we
> didn't rely on mmu_notifier_unregister to succeed. So it avoided any
> DoS but it still can't provide any reliable unregister.

If unregister fails then the driver should not detach from the address
space immediately but wait until -->release is called. That may be
a possible solution. It will be rare that the unregister fails.