On Tue, Sep 6, 2022 at 7:43 AM Laurent Dufour <ldufour@xxxxxxxxxxxxx> wrote: > > Le 01/09/2022 à 19:34, Suren Baghdasaryan a écrit : > > Protect VMA from concurrent page fault handler while modifying it in > > collapse_huge_page. > > Is the goal to protect changes in the anon_vma structure? > > AFAICS, the vma it self is not impacted here, only the anon_vma and the > PMD/PTE are touched, and they have their own protection mechanism, isn't it? Yes, I think you are right about not needing to lock VMA here as all modified components are already protected. Thanks! > > > > > Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> > > --- > > mm/khugepaged.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > > index 01f71786d530..030680633989 100644 > > --- a/mm/khugepaged.c > > +++ b/mm/khugepaged.c > > @@ -1072,6 +1072,7 @@ static void collapse_huge_page(struct mm_struct *mm, > > if (mm_find_pmd(mm, address) != pmd) > > goto out_up_write; > > > > + vma_mark_locked(vma); > > anon_vma_lock_write(vma->anon_vma); > > > > mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, >
