Re: [PATCH v2 1/5] userfaultfd: introduce uffd_flags

[David Hildenbrand <david@redhat.com>]

On 18.07.22 13:47, Nadav Amit wrote:
> From: Nadav Amit <namit@vmware.com>
> 
> As the next patches are going to introduce more information that needs
> to be propagated regarding handled user requests, introduce uffd_flags
> that would be used to propagate this information.
> 
> Remove the unused UFFD_FLAGS_SET to avoid confusion in the constant
> names.
> 
> Introducing uffd flags also allows to avoid mm/userfaultfd from being
> using uapi (e.g., UFFDIO_COPY_MODE_WP).
> 
> Cc: Mike Kravetz <mike.kravetz@oracle.com>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Axel Rasmussen <axelrasmussen@google.com>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Mike Rapoport <rppt@linux.ibm.com>
> Acked-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Nadav Amit <namit@vmware.com>

[...]

>  
>  int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start,
> -			unsigned long len, bool enable_wp,
> -			atomic_t *mmap_changing)
> +			unsigned long len,
> +			atomic_t *mmap_changing, uffd_flags_t uffd_flags)
>  {
> +	bool enable_wp = uffd_flags & UFFD_FLAGS_WP;

Could be that this will trigger a sparse warnings, but I haven't fully
understood yet when/how sparse will start to complain. If so, this would
have to be

bool enable_wp = !!(uffd_flags & UFFD_FLAGS_WP);

I stumbled into something like that in
https://lore.kernel.org/lkml/202202252038.ij1YGn0d-lkp@intel.com/T/


Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb