mm/THP: withdraw the pgtable after pmdp related operations

For architectures like ppc64 we look at deposited pgtable when calling
pmdp_get_and_clear.  So do the pgtable_trans_huge_withdraw after finishing
pmdp related operations.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6b785e17b679..5c4fac2d239e 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1360,9 +1360,15 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
                 struct page *page;
                 pgtable_t pgtable;
                 pmd_t orig_pmd;
-                pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
+                /*
+                 * For architectures like ppc64 we look at deposited pgtable
+                 * when calling pmdp_get_and_clear. So do the
+                 * pgtable_trans_huge_withdraw after finishing pmdp related
+                 * operations.
+                 */
                 orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
                 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
+                pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
                 if (is_huge_zero_pmd(orig_pmd)) {
                         tlb->mm->nr_ptes--;
                         spin_unlock(&tlb->mm->page_table_lock);