Le 01/09/2022 à 19:35, Suren Baghdasaryan a écrit :
> Mark VMAs as locked before isolating them and clear their tree node so
> that isolated VMAs are easily identifiable. In the later patches page
> fault handlers will try locking the found VMA and will check whether
> the VMA was isolated. Locking VMAs before isolating them ensures that
> page fault handlers don't operate on isolated VMAs.
Found another place where the VMA should probably mark locked:
*** drivers/gpu/drm/drm_vma_manager.c:
drm_vma_node_revoke[338] rb_erase(&entry->vm_rb, &node->vm_files);
There are 2 others entries in nommu.c but I guess this is not supported,
isn't it?
> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> ---
> mm/mmap.c | 2 ++
> mm/nommu.c | 2 ++
> 2 files changed, 4 insertions(+)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 094678b4434b..b0d78bdc0de0 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -421,12 +421,14 @@ static inline void vma_rb_insert(struct vm_area_struct *vma,
>
> static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
> {
> + vma_mark_locked(vma);
> /*
> * Note rb_erase_augmented is a fairly large inline function,
> * so make sure we instantiate it only once with our desired
> * augmented rbtree callbacks.
> */
> rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
> + RB_CLEAR_NODE(&vma->vm_rb);
> }
>
> static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
> diff --git a/mm/nommu.c b/mm/nommu.c
> index e819cbc21b39..ff9933e57501 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -622,6 +622,7 @@ static void delete_vma_from_mm(struct vm_area_struct *vma)
> struct mm_struct *mm = vma->vm_mm;
> struct task_struct *curr = current;
>
> + vma_mark_locked(vma);
> mm->map_count--;
> for (i = 0; i < VMACACHE_SIZE; i++) {
> /* if the vma is cached, invalidate the entire cache */
> @@ -644,6 +645,7 @@ static void delete_vma_from_mm(struct vm_area_struct *vma)
>
> /* remove from the MM's tree and list */
> rb_erase(&vma->vm_rb, &mm->mm_rb);
> + RB_CLEAR_NODE(&vma->vm_rb);
>
> __vma_unlink_list(mm, vma);
> }
