Re: [PATCH v17 08/10] PM: hibernate: disable when there are active secretmem users

Michal Hocko
2021-02-08T10:52:01Z

On Mon 08-02-21 11:32:11, David Hildenbrand wrote:
> On 08.02.21 11:18, Michal Hocko wrote:
> > On Mon 08-02-21 10:49:18, Mike Rapoport wrote:
> > > From: Mike Rapoport <rppt@linux.ibm.com>
> > >
> > > It is unsafe to allow saving of secretmem areas to the hibernation
> > > snapshot as they would be visible after the resume and this essentially
> > > will defeat the purpose of secret memory mappings.
> > >
> > > Prevent hibernation whenever there are active secret memory users.
> >
> > Does this feature need any special handling? As it is effectivelly
> > unevictable memory then it should behave the same as other mlock, ramfs
> > which should already disable hibernation as those cannot be swapped out,
> > no?
> >
>
> Why should unevictable memory not go to swap when hibernating? We're merely
> dumping all of our system RAM (including any unmovable allocations) to swap
> storage and the system is essentially completely halted.
>
My understanding is that mlock is never really made visible via swap
storage.
--
Michal Hocko
SUSE Labs