Messages in this thread | | | Date | Sat, 26 Jan 2008 05:56:39 -0600 | From | Robin Holt <> | Subject | Re: [patch 1/4] mmu_notifier: Core code |
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> > > 1. invalidate_all() > > > > That will be fine as long as we can unregister the ops notifier and free > > the structure. Otherwise, we end up being called needlessly. > > 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.
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?
> > > > 2. invalidate_range() for each vma > > > > > > 3. release() > > > > > > We cannot simply move the call up because there will be future range > > > callbacks on vma invalidation. > > > > I am not sure what this means. Right now, if you were to notify XPMEM > > the process is exiting, we would take care of all the recalling of pages > > exported by this process, clearing those pages cache lines from cache, > > and raising memory protections. I would assume that moving the callout > > earlier would expect the same of every driver. > > 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.
Thanks, Robin
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