[PATCH 4.0 025/220] powerpc/hugetlb: Call mm_dec_nr_pmds() in hugetlb_free_pmd_range()

[Greg Kroah-Hartman]

4.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Scott Wood <scottwood@xxxxxxxxxxxxx>

commit 50c6a665b383cb5839e45d04e36faeeefaffa052 upstream.

Commit dc6c9a35b66b5 ("mm: account pmd page tables to the process")
added a counter that is incremented whenever a PMD is allocated and
decremented whenever a PMD is freed.  For hugepages on PPC, common code
is used to allocated PMDs, but arch-specific code is used to free PMDs.

This results in kernel output such as "BUG: non-zero nr_pmds on freeing
mm: 1" when using hugepages.

Update the PPC hugepage PMD freeing code to decrement the count, just
as the above commit did for free_pmd_range().

Fixes: dc6c9a35b66b5 ("mm: account pmd page tables to the process")
Signed-off-by: Scott Wood <scottwood@xxxxxxxxxxxxx>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/powerpc/mm/hugetlbpage.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -581,6 +581,7 @@ static void hugetlb_free_pmd_range(struc
 	pmd = pmd_offset(pud, start);
 	pud_clear(pud);
 	pmd_free_tlb(tlb, pmd, start);
+	mm_dec_nr_pmds(tlb->mm);
 }
 
 static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,


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