Re: [patch 1/6] mmu_notifier: Core code

Christoph Lameter
2008-02-05T18:19:41Z

On Tue, 5 Feb 2008, Andy Whitcroft wrote:

> > + if (unlikely(!hlist_empty(&mm->mmu_notifier.head))) {
> > + rcu_read_lock();
> > + hlist_for_each_entry_safe_rcu(mn, n, t,
> > + &mm->mmu_notifier.head, hlist) {
> > + if (mn->ops->release)
> > + mn->ops->release(mn, mm);
>
> Does this ->release actually release the 'nm' and its associated hlist?
> I see in this thread that this ordering is deemed "use after free" which
> implies so.

Right that was fixed in a later release and discussed extensively later.
See V5.

> I am not sure it makes sense to add a _safe_rcu variant. As I understand
> things an _safe variant is used where we are going to remove the current

It was dropped in V5.