Le 01/09/2022 à 19:34, Suren Baghdasaryan a écrit :
> Protect VMA from concurrent page fault handler while performing VMA
> protection policy changes.
>
> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> ---
> mm/mempolicy.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index b73d3248d976..6be1e5c75556 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -383,8 +383,10 @@ void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
> struct vm_area_struct *vma;
>
> mmap_write_lock(mm);
> - for (vma = mm->mmap; vma; vma = vma->vm_next)
> + for (vma = mm->mmap; vma; vma = vma->vm_next) {
> + vma_mark_locked(vma);
> mpol_rebind_policy(vma->vm_policy, new);
> + }
> mmap_write_unlock(mm);
> }
>
> @@ -632,6 +634,7 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
> struct mmu_gather tlb;
> int nr_updated;
>
> + vma_mark_locked(vma);
If I understand that corretly, the VMA itself is not impacted, only the
PMDs/PTEs, and they are protected using the page table locks.
Am I missing something?
> tlb_gather_mmu(&tlb, vma->vm_mm);
>
> nr_updated = change_protection(&tlb, vma, addr, end, PAGE_NONE,
> @@ -765,6 +768,7 @@ static int vma_replace_policy(struct vm_area_struct *vma,
> if (IS_ERR(new))
> return PTR_ERR(new);
>
> + vma_mark_locked(vma);
> if (vma->vm_ops && vma->vm_ops->set_policy) {
> err = vma->vm_ops->set_policy(vma, new);
> if (err)
