Re: [PATCH 5/6] userfaultfd: decouple fault reason from VMA flags

[David Hildenbrand (Arm)]

On 8/23/26 14:17, Mike Rapoport (Microsoft) wrote:
> Introduce enum uffd_reason to define reasons for user faults rather than
> overload VM_UFFD_* VMA flags for that.
> 
> Using a dedicated enum makes the code clearer and decoupling the fault
> reason from VMA flags clears the way for moving the uffd mode bits out
> of VMA namespace.
> 
> No functional change.
> 
> Assisted-by: copilot:claude-opus-4.6
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
> ---
>  include/linux/userfaultfd_k.h    | 16 ++++++++++++++--
>  include/uapi/linux/userfaultfd.h |  6 +++---
>  mm/huge_memory.c                 |  6 +++---
>  mm/hugetlb.c                     | 10 +++++-----
>  mm/memory.c                      | 10 +++++-----
>  mm/shmem.c                       |  4 ++--
>  mm/userfaultfd.c                 | 30 +++++++++++++++---------------
>  7 files changed, 47 insertions(+), 35 deletions(-)
> 
> diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
> index 45355bdb4ec7..f401623f315d 100644
> --- a/include/linux/userfaultfd_k.h
> +++ b/include/linux/userfaultfd_k.h
> @@ -9,6 +9,18 @@
>  #ifndef _LINUX_USERFAULTFD_K_H
>  #define _LINUX_USERFAULTFD_K_H
>  
> +#include <linux/bits.h>
> +
> +/* Fault reason #PF handler passes to handle_userfault() */
> +enum uf_reason {

Can we just call this "userfault_reason" or "uffd_reason" ? Maybe the latter is
actually what we want?

-- 
Cheers,

David