Re: mm: NULL ptr deref handling mmaping of special mappings

Cyrill Gorcunov
2014-05-15T21:57:28Z

On Thu, May 15, 2014 at 02:42:48PM -0700, Andy Lutomirski wrote:
> >
> > Looking forward the question appear -- will VDSO_PREV_PAGES and rest of variables
> > be kind of immutable constants? If yes, we could calculate where the additional
> > vma lives without requiring any kind of [vdso] mark in proc/pid/maps output.
>
> Please don't!
>
> These might, in principle, even vary between tasks on the same system.
> Certainly the relative positions of the vmas will be different
> between 3.15 and 3.16, since we need almost my entire cleanup series
> to reliably put them into their 3.16 location. And I intend to change
> the number of pages in 3.16 or 3.17.

There are other ways how to find where additional pages are laying but it
would be great if there a straightforward interface for that (ie some mark
in /proc/pid/maps output).