On Thu, May 30, 2019 at 02:10:15PM +0300, Kirill A. Shutemov wrote:
> On Wed, May 29, 2019 at 02:20:46PM -0700, Song Liu wrote:
> > @@ -2133,10 +2133,15 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
> > VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
> > VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
> > && !pmd_devmap(*pmd));
> > + /* only file backed vma need preallocate pgtable*/
> > + VM_BUG_ON(vma_is_anonymous(vma) && prealloc_pgtable);
> >
> > count_vm_event(THP_SPLIT_PMD);
> >
> > - if (!vma_is_anonymous(vma)) {
> > + if (prealloc_pgtable) {
> > + pgtable_trans_huge_deposit(mm, pmd, prealloc_pgtable);
> > + mm_inc_nr_pmds(mm);
> > + } else if (!vma_is_anonymous(vma)) {
> > _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
> > /*
> > * We are going to unmap this huge page. So
>
> Nope. This going to leak a page table for architectures where
> arch_needs_pgtable_deposit() is true.
And I don't there's correct handling of dirty bit.
And what about DAX? Will it blow up? I think so.
--
Kirill A. Shutemov
