Re: [PATCH 0/4] mm: permit guard regions for file-backed/shmem mappings

[David Hildenbrand]

> > As for compatibility with VM_LOCKONFAULT, do we need a new
> > MADV_GUARD_INSTALL_LOCKED or can we say MADV_GUARD_INSTALL is new enough
> > that it can be just retrofitted (like you retrofit file backed mappings)?
> > AFAIU the only risk would be breaking somebody that already relies on a
> > failure for VM_LOCKONFAULT, and it's unlikely there's such a somebody now.
>
> Hmm yeah I suppose. I guess just to be consistent with the other _LOCKED
> variants? (which seem to be... undocumented at least in man pages :P, and yes I
> realise this is me semi-volunteering to do that obviously...).
>
> But on the other hand, we could also expand this if you and I see also Dave feel
> this makes sense and wouldn't be confusing.

Just my 2 cents: one thing that came to mind: an existing library would 
have to be updated to use the _LOCKED variant if the app would be using 
mlockall(future), which is a bit unfortunate -- and if it could be 
avoided, it would be great.

But yeah, devil is in the detail ...

--
Cheers,

David / dhildenb