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SubjectRe: [PATCH] hugetlb: powerpc: Actively close unused htlb regions on vma close
On Fri, 2 Jun 2006, Adam Litke wrote:

> The following patch introduces a architecture-specific vm_ops.close()
> hook. For all architectures besides powerpc, this is a no-op. On
> powerpc, the low and high segments are scanned to locate empty hugetlb
> segments which can be made available for normal mappings. Comments?

IA64 has similar issues and uses the hook suggested by Hugh. However, we
have a permanently reserved memory area. I am a bit surprised about the
need to make address space available for normal mappings. Is this for 32
bit powerpc support?

void hugetlb_free_pgd_range(struct mmu_gather **tlb,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
/*
* This is called to free hugetlb page tables.
*
* The offset of these addresses from the base of the hugetlb
* region must be scaled down by HPAGE_SIZE/PAGE_SIZE so that
* the standard free_pgd_range will free the right page tables.
*
* If floor and ceiling are also in the hugetlb region, they
* must likewise be scaled down; but if outside, left unchanged.
*/
addr = htlbpage_to_page(addr);
end = htlbpage_to_page(end);
if (REGION_NUMBER(floor) == RGN_HPAGE)
floor = htlbpage_to_page(floor);
if (REGION_NUMBER(ceiling) == RGN_HPAGE)
ceiling = htlbpage_to_page(ceiling);
free_pgd_range(tlb, addr, end, floor, ceiling);
}
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