static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm,
					    unsigned long dst_start,
					    unsigned long src_start,
					    unsigned long len,
					    atomic_t *mmap_changing,
					    uffd_flags_t flags)
static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx,
					    unsigned long dst_start,
					    unsigned long src_start,
					    unsigned long len,
					    uffd_flags_t flags)