Re: [Qemu-devel] [PATCH 07/17] mm: madvise MADV_USERFAULT: prepare vm_flags to allow more than 32bits

[Kirill A. Shutemov]

On Fri, Oct 03, 2014 at 07:07:57PM +0200, Andrea Arcangeli wrote:
> We run out of 32bits in vm_flags, noop change for 64bit archs.
> 
> Signed-off-by: Andrea Arcangeli <address@hidden>
> ---
>  fs/proc/task_mmu.c       | 4 ++--
>  include/linux/huge_mm.h  | 4 ++--
>  include/linux/ksm.h      | 4 ++--
>  include/linux/mm_types.h | 2 +-
>  mm/huge_memory.c         | 2 +-
>  mm/ksm.c                 | 2 +-
>  mm/madvise.c             | 2 +-
>  mm/mremap.c              | 2 +-
>  8 files changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index c341568..ee1c3a2 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -532,11 +532,11 @@ static void show_smap_vma_flags(struct seq_file *m, 
> struct vm_area_struct *vma)
>       /*
>        * Don't forget to update Documentation/ on changes.
>        */
> -     static const char mnemonics[BITS_PER_LONG][2] = {
> +     static const char mnemonics[BITS_PER_LONG+1][2] = {

I believe here and below should be BITS_PER_LONG_LONG instead: it will
catch unknown vmflags. And +1 is not needed un 64-bit systems.

>               /*
>                * In case if we meet a flag we don't know about.
>                */
> -             [0 ... (BITS_PER_LONG-1)] = "??",
> +             [0 ... (BITS_PER_LONG)] = "??",
>  
>               [ilog2(VM_READ)]        = "rd",
>               [ilog2(VM_WRITE)]       = "wr",
-- 
 Kirill A. Shutemov