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Subjecthugepage: Fix hugepage logic in free_pgtables() harder
Sigh.  Turns out the hugepage logic in free_pgtables() was doubly
broken. The loop coalescing multiple normal page VMAs into one call
to free_pgd_range() had an off by one error, which could mean it would
coalesce one hugepage VMA into the same bundle (checking 'vma' not
'next' in the loop). I transferred this bug into the new
is_vm_hugetlb_page() based version. Here's the fix.

This one didn't bite on powerpc previously for the same reason the
is_hugepage_only_range() problem didn't: powerpc's
hugetlb_free_pgd_range() is identical to free_pgd_range(). It didn't
bite on ia64 because the hugepage region is distant enough from any
other region that the separated PMD_SIZE distance test would always
prevent coalescing the two together.

No libhugetlbfs testsuite regressions (ppc64, POWER5).

Signed-off-by: David Gibson <dwg@au1.ibm.com>

Index: working-2.6/mm/memory.c
===================================================================
--- working-2.6.orig/mm/memory.c 2006-03-03 11:39:33.000000000 +1100
+++ working-2.6/mm/memory.c 2006-03-03 11:39:50.000000000 +1100
@@ -285,7 +285,7 @@ void free_pgtables(struct mmu_gather **t
* Optimization: gather nearby vmas into one call down
*/
while (next && next->vm_start <= vma->vm_end + PMD_SIZE
- && !is_vm_hugetlb_page(vma)) {
+ && !is_vm_hugetlb_page(next)) {
vma = next;
next = vma->vm_next;
anon_vma_unlink(vma);

--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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