Re: [RFC] Track mlock()ed pages

[Christoph Lameter]

On Fri, 26 Jan 2007, Andrew Morton wrote:

> > > > Track mlocked pages via a ZVC
> 
> Why?

Large amounts of mlocked pages may be a problem for 

1. Reclaim behavior.

2. Defragmentation


> You could perhaps go for a walk across all the other vmas which presently
> map this page.  If any of them have VM_LOCKED, don't increment the counter.
> Similar on removal: only decrement the counter when the final mlocked VMA
> is dropping the pte.

For that we would need an additional refcount for vmlocked maps in the 
page struct. Looks too expensive.
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