[PATCH] hugepage: Fix hugepage logic in free_pgtables() harder

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>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/memory.c b/mm/memory.c
index f6e3be9..80c3fb3 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -285,7 +285,7 @@ void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
                         * 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);