Messages in this thread | | | Date | Mon, 28 Jan 2008 10:51:03 -0800 (PST) | From | Christoph Lameter <> | Subject | Re: [patch 1/4] mmu_notifier: Core code |
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On Sat, 26 Jan 2008, Robin Holt wrote:
> > No you cannot do that because there are still callbacks that come later. > > The invalidate_all may lead to invalidate_range() doing nothing for this > > mm. The ops notifier and the freeing of the structure has to wait until > > release(). > > Could you be a little more clear here? If you are saying that the other > callbacks will need to do work? I can assure you we will clean up those > pages and raise memory protections. It will also be done in a much more > efficient fashion than the individual callouts.
No the other callbacks need to work in the sense that they can be called. You could have them do nothing after an invalidate_all(). But you cannot release the allocated structs needed for list traversal etc.
> If, on the other hand, you are saying we can not because of the way > we traverse the list, can we return a result indicating to the caller > we would like to be unregistered and then the mmu_notifier code do the > remove followed by a call to the release notifier?
You would need to release the resources when the release notifier is called.
> > That does not sync with the current scheme of the invalidate_range() > > hooks. We would have to do a global invalidate early and then place the > > other invalidate_range hooks in such a way that none is called in later in > > process exit handling. > > But if the notifier is removed from the list following the invalidate_all > callout, there would be no additional callouts.
Hmmm.... Okay did not think about that. Then you would need to do a synchronize_rcu() in invalidate_all()?
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