Re: [PATCH] hugetlb: Fix pool resizing corner case

From: Ken Chen
Date: Wed Oct 03 2007 - 15:09:21 EST


On 10/3/07, Dave Hansen <haveblue@xxxxxxxxxx> wrote:
> > Not quite. Count can never go below the number of reserved pages plus
> > pages allocated to MAP_PRIVATE mappings. That number is computed by:
> > (resv + (total - free)).
>
> So, (total - free) equals the number of MAP_PRIVATE pages? Does that
> imply that all reserved pages are shared and that all shared pages are
> reserved?

no, not quite. In-use huge page (total - free) can be both private or
shared. resv_huge_pages counts number of pages that is committed for
shared mapping, but not yet faulted in.

What the equation does essentially is: resv_huge_pages + nr-huge-pages-in-use.

- Ken
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