Re: [RFC] Track mlock()ed pages

Nick Piggin
2007-01-26T12:00:22Z

Andrew Morton wrote:
> On Thu, 25 Jan 2007 22:36:17 -0800 (PST)
> Christoph Lameter <clameter@sgi.com> wrote:
>

>>>I can't think of an easy way to do this without per-page state. ie.
>>>another page flag.
>>
>>Thats what I am trying to avoid.
>
>
> 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.

Can't do with un-racily because you can't get that information
atomically, AFAIKS. When / if we ever lock the page in fault handler,
this could become easier... but that seems nasty to do in fault path,
even if only for VM_LOCKED vmas.

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SUSE Labs, Novell Inc.
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