diff options
Diffstat (limited to 'mm/userfaultfd.c')
| -rw-r--r-- | mm/userfaultfd.c | 30 |
1 files changed, 23 insertions, 7 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 48ac81bbfee6..fbf2cf62ab9f 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -85,8 +85,12 @@ static struct vm_area_struct *uffd_lock_vma(struct mm_struct *mm, mmap_read_lock(mm); vma = find_vma_and_prepare_anon(mm, address); - if (!IS_ERR(vma)) - vma_start_read_locked(vma); + if (!IS_ERR(vma)) { + bool locked = vma_start_read_locked(vma); + + if (!locked) + vma = ERR_PTR(-EAGAIN); + } mmap_read_unlock(mm); return vma; @@ -1555,12 +1559,24 @@ static int uffd_move_lock(struct mm_struct *mm, mmap_read_lock(mm); err = find_vmas_mm_locked(mm, dst_start, src_start, dst_vmap, src_vmap); - if (!err) { - vma_start_read_locked(*dst_vmap); - if (*dst_vmap != *src_vmap) - vma_start_read_locked_nested(*src_vmap, - SINGLE_DEPTH_NESTING); + if (err) + goto out; + + if (!vma_start_read_locked(*dst_vmap)) { + err = -EAGAIN; + goto out; } + + /* Nothing further to do if both vmas are locked. */ + if (*dst_vmap == *src_vmap) + goto out; + + if (!vma_start_read_locked_nested(*src_vmap, SINGLE_DEPTH_NESTING)) { + /* Undo dst_vmap locking if src_vmap failed to lock */ + vma_end_read(*dst_vmap); + err = -EAGAIN; + } +out: mmap_read_unlock(mm); return err; } |