Re: [PATCH v1 2/2] mm/hugetlb: fix hugetlb vs. core-mm PT locking

[David Hildenbrand]

> > > +     *
> > > +     * If that does not hold for an architecture, then that architecture
> > > +     * must disable split PT locks such that all *_lockptr() functions
> > > +     * will give us the same result: the per-MM PT lock.
> > > +     */
> > > +    if (huge_page_size(h) < PMD_SIZE)
> > > +        return pte_lockptr(mm, pte);
> > > +    else if (huge_page_size(h) < PUD_SIZE)
> > >            return pmd_lockptr(mm, (pmd_t *) pte);
> >
> > IIUC, as I said above, this change doesn't fix the inconsistent lock for
> > cont-PMD size hugetlb for GUP, and it will also break the lock rule for
> > unmapping/migrating a cont-PMD size hugetlb (use mm->page_table_lock
> > before for cont-PMD size hugetlb before).
>
> After more thinking, I realized I confused the PMD table with the PMD
> entry. Therefore, using the PMD table's lock is safe for cont-PMD size
> hugetlb. This change looks good to me. Sorry for noise.

Thanks for the review, highly appreciated!

--
Cheers,

David / dhildenb