Re: [RFC] mlock/stack guard interaction fixup

Jeremy Fitzhardinge
2010-08-23T19:54:15Z

On 08/23/2010 12:26 PM, Peter Zijlstra wrote:
> 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.

Won't dirty anonymous pages also get written to swap?

J