Hugh Dickins wrote on Thursday, March 02, 2006 10:53 AM
> On Thu, 2 Mar 2006, 'David Gibson' wrote:
> > free_pgtables() has special logic to call hugetlb_free_pgd_range()
> > instead of the normal free_pgd_range() on hugepage VMAs. However, the
> > test it uses to do so is incorrect: it calls is_hugepage_only_range on
> > a hugepage sized range at the start of the vma.
> > is_hugepage_only_range() will return true if the given range has any
> > intersection with a hugepage address region, and in this case the
> > given region need not be hugepage aligned. So, for example, this test
> > can return true if called on, say, a 4k VMA immediately preceding a
> > (nicely aligned) hugepage VMA.
> >
> > At present we get away with this because the powerpc version of
> > hugetlb_free_pgd_range() is just a call to free_pgd_range(). On ia64
> > (the only other arch with a non-trivial is_hugepage_only_range()) we
> > get away with it for a different reason; the hugepage area is not
> > contiguous with the rest of the user address space, and VMAs are not
> > permitted in between, so the test can't return a false positive there.
> >
> > Nonetheless this should be fixed. We do that in the patch below by
> > replacing the is_hugepage_only_range() test with an explicit test of
> > the VMA using is_vm_hugetlb_page().
> >
> Yes, okay, you can add my
>
> Acked-by: Hugh Dickins <[email protected]>
>
> (ARCH_HAS... and HAVE_ARCH... have fallen into disfavour, but I
> don't think you're doing wrong by splitting the old one into two.)
>
> But let me emphasize again, in case Andrew wonders, that no current bug
> is fixed by this (as indeed you indicate in your "we get away with this"
> comments).
I've double checked that David's patch is OK for ia64.
> 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.
[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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