Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR

[Kirill A. Shutemov]

On Thu, Jan 05, 2017 at 11:13:57AM -0800, Dave Hansen wrote:
> On 12/26/2016 05:54 PM, Kirill A. Shutemov wrote:
> > MM would use min(RLIMIT_VADDR, TASK_SIZE) as upper limit of virtual
> > address available to map by userspace.
> 
> What happens to existing mappings above the limit when this upper limit
> is dropped?

Nothing: we only prevent creating new mappings. All existing are not
affected.

The semantics here the same as with other resource limits.

> Similarly, why do we do with an application running with something
> incompatible with the larger address space that tries to raise the
> limit?  Say, legacy MPX.

It has to know what it does. Yes, it can change limit to the point where
application is unusable. But you can to the same with other limits.

-- 
 Kirill A. Shutemov