Re: [PATCH 6/6] mm: Forbid splitting special mappings

[Will Deacon]

On Tue, Oct 13, 2020 at 02:34:16AM +0100, Dmitry Safonov wrote:
> Don't allow splitting of vm_special_mapping's.
> It affects vdso/vvar areas. Uprobes have only one page in xol_area so
> they aren't affected.
> 
> Those restrictions were enforced by checks in .mremap() callbacks.
> Restrict resizing with generic .split() callback.
> 
> Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
> ---
>  arch/arm/kernel/vdso.c    |  9 ---------
>  arch/arm64/kernel/vdso.c  | 41 +++------------------------------------
>  arch/mips/vdso/genvdso.c  |  4 ----
>  arch/s390/kernel/vdso.c   | 11 +----------
>  arch/x86/entry/vdso/vma.c | 17 ----------------
>  mm/mmap.c                 | 12 ++++++++++++
>  6 files changed, 16 insertions(+), 78 deletions(-)

For arm64:

Acked-by: Will Deacon <will@xxxxxxxxxx>

Will