Re: [RFC] mlock/stack guard interaction fixup

Peter Zijlstra
2010-08-23T19:26:55Z

On Mon, 2010-08-23 at 12:23 -0700, Jeremy Fitzhardinge wrote:
> On 08/23/2010 12:07 PM, Peter Zijlstra wrote:
> > mlock() simply avoids major faults, nothing more.
> >
> > I think both page migration and page-out for shared pages where some
> > maps are !mlocked can cause unmaps and thus minor faults.
> >
> > mlock and dirty do not interact, they will still be cleaned/written out
> > as normal.
>
> So mlock is useless for preventing secret stuff from being written to disk.

Well, if you put your sekrit in a file map, sure.

Use a mmap(MAP_ANONYMOUS|MAP_LOCK) and madvise(MADV_DONTFORK) for your
sekrits.