[openib-general] Re: madvise MADV_DONTFORK/MADV_DOFORK

[Hugh Dickins]

On Tue, 14 Feb 2006, Michael S. Tsirkin wrote:
> Quoting r. Hugh Dickins <hugh at veritas.com>:
> 
> > Comments much better, thanks.  I didn't get your point about mlock'd
> > memory, but I'm content to believe you're thinking of an issue that
> > hasn't occurred to me.
> 
> I'm referring to the follwing, from man mlock(2):
> 
> "Cryptographic  security  software often handles critical bytes like passwords
> or secret keys as data structures. As a result of paging, these secrets could
> be  transfered  onto  a persistent swap store medium, where they might be
> accessible to the enemy long after the security  software  has erased the
> secrets in RAM and terminated."

Ah, I get it, thanks: once parent and child have distinct pages,
the child's is not locked in memory and might go out to swap.
Yes, a valid point, and a relevant use for MADV_DONTFORK.

Hugh