On Thu, 2 Mar 2006, Chen, Kenneth W wrote:
> Hugh Dickins wrote on Thursday, March 02, 2006 10:53 AM
>
> > Whereas there's still a real ia64 get_unmapped_area bug to be fixed,
> > arising from the same confusion, that is_hugepage_only_range needs
> > to mean overlaps_hugepage_only_range (as on PowerPC) rather than
> > within_hugepage_only_range (as on IA64). Is Ken fixing that one?
>
> Yes, I'm fixing it. See patch below.
Great, thanks. The second part, using REGION_NUMBER instead of
is_hugepage_only_range in the ia64 hugetlb_free_pgd_range, looks nice.
But the first part, || instead of && in is_hugepage_only_range, looks
insufficient: the start and end of the range might each fall in a
non-huge region, but the range still cross a huge region.
Ah, does RGN_HPAGE nestle up against the TASK_SIZE roof, so any range
already tested against TASK_SIZE (as get_unmapped_area has) cannot
cross RGN_HPAGE? If so, perhaps it deserves a comment there. And
if that is so, and can be relied upon, is_hugepage_only_range need
only be testing REGION_NUMBER(addr+len-1) - but it does seem fragile.
Hugh
>
> [patch] ia64: fix is_hugepage_only_range() definition to be overlaps
> instead of within architectural restricted hugetlb address
> range. Fix all affected usages.
>
> Signed-off-by: Ken Chen <[email protected]>
>
> --- ./include/asm-ia64/page.h.orig 2006-03-02 12:16:00.636688455 -0800
> +++ ./include/asm-ia64/page.h 2006-03-02 12:23:30.151331386 -0800
> @@ -147,7 +147,7 @@ typedef union ia64_va {
> | (REGION_OFFSET(x) >> (HPAGE_SHIFT-PAGE_SHIFT)))
> # define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
> # define is_hugepage_only_range(mm, addr, len) \
> - (REGION_NUMBER(addr) == RGN_HPAGE && \
> + (REGION_NUMBER(addr) == RGN_HPAGE || \
> REGION_NUMBER((addr)+(len)-1) == RGN_HPAGE)
> extern unsigned int hpage_shift;
> #endif
> --- ./arch/ia64/mm/hugetlbpage.c.orig 2006-03-02 12:31:12.020466353 -0800
> +++ ./arch/ia64/mm/hugetlbpage.c 2006-03-02 12:31:02.944294589 -0800
> @@ -112,8 +112,7 @@ void hugetlb_free_pgd_range(struct mmu_g
> unsigned long floor, unsigned long ceiling)
> {
> /*
> - * This is called only when is_hugepage_only_range(addr,),
> - * and it follows that is_hugepage_only_range(end,) also.
> + * 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
> @@ -125,9 +124,9 @@ void hugetlb_free_pgd_range(struct mmu_g
>
> addr = htlbpage_to_page(addr);
> end = htlbpage_to_page(end);
> - if (is_hugepage_only_range(tlb->mm, floor, HPAGE_SIZE))
> + if (REGION_NUMBER(floor) == RGN_HPAGE)
> floor = htlbpage_to_page(floor);
> - if (is_hugepage_only_range(tlb->mm, ceiling, HPAGE_SIZE))
> + if (REGION_NUMBER(ceiling) == RGN_HPAGE)
> ceiling = htlbpage_to_page(ceiling);
>
> free_pgd_range(tlb, addr, end, floor, ceiling);
-
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