Can we change this to active/inactive? I think there is potential for
reusing this functionality to even larger degrees and that name would
fit better and would still make sense in this context.
ie: vma_mark_active() and vma_mark_inactive() ?
* Suren Baghdasaryan <surenb@xxxxxxxxxx> [230216 00:18]:
> Per-vma locking mechanism will search for VMA under RCU protection and
> then after locking it, has to ensure it was not removed from the VMA
> tree after we found it. To make this check efficient, introduce a
> vma->detached flag to mark VMAs which were removed from the VMA tree.
>
> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> ---
> include/linux/mm.h | 11 +++++++++++
> include/linux/mm_types.h | 3 +++
> mm/mmap.c | 2 ++
> 3 files changed, 16 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index f4f702224ec5..3f98344f829c 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -693,6 +693,14 @@ static inline void vma_assert_write_locked(struct vm_area_struct *vma)
> VM_BUG_ON_VMA(vma->vm_lock_seq != READ_ONCE(vma->vm_mm->mm_lock_seq), vma);
> }
>
> +static inline void vma_mark_detached(struct vm_area_struct *vma, bool detached)
> +{
> + /* When detaching vma should be write-locked */
> + if (detached)
> + vma_assert_write_locked(vma);
> + vma->detached = detached;
> +}
> +
> #else /* CONFIG_PER_VMA_LOCK */
>
> static inline void vma_init_lock(struct vm_area_struct *vma) {}
> @@ -701,6 +709,8 @@ static inline bool vma_start_read(struct vm_area_struct *vma)
> static inline void vma_end_read(struct vm_area_struct *vma) {}
> static inline void vma_start_write(struct vm_area_struct *vma) {}
> static inline void vma_assert_write_locked(struct vm_area_struct *vma) {}
> +static inline void vma_mark_detached(struct vm_area_struct *vma,
> + bool detached) {}
>
> #endif /* CONFIG_PER_VMA_LOCK */
>
> @@ -712,6 +722,7 @@ static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm)
> vma->vm_mm = mm;
> vma->vm_ops = &dummy_vm_ops;
> INIT_LIST_HEAD(&vma->anon_vma_chain);
> + vma_mark_detached(vma, false);
> vma_init_lock(vma);
> }
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index e268723eaf44..939f4f5a1115 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -511,6 +511,9 @@ struct vm_area_struct {
> #ifdef CONFIG_PER_VMA_LOCK
> int vm_lock_seq;
> struct rw_semaphore lock;
> +
> + /* Flag to indicate areas detached from the mm->mm_mt tree */
> + bool detached;
> #endif
>
> /*
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 801608726be8..adf40177e68f 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -593,6 +593,7 @@ static inline void vma_complete(struct vma_prepare *vp,
>
> if (vp->remove) {
> again:
> + vma_mark_detached(vp->remove, true);
> if (vp->file) {
> uprobe_munmap(vp->remove, vp->remove->vm_start,
> vp->remove->vm_end);
> @@ -2267,6 +2268,7 @@ static inline int munmap_sidetree(struct vm_area_struct *vma,
> if (mas_store_gfp(mas_detach, vma, GFP_KERNEL))
> return -ENOMEM;
>
> + vma_mark_detached(vma, true);
> if (vma->vm_flags & VM_LOCKED)
> vma->vm_mm->locked_vm -= vma_pages(vma);
>
> --
> 2.39.1
>
