thp: introduce pmdp_invalidate()

On s390, a valid page table entry must not be changed while it is attached
to any CPU.  So instead of pmd_mknotpresent() and set_pmd_at(), an IDTE
operation would be necessary there.  This patch introduces the
pmdp_invalidate() function, to allow architecture-specific
implementations.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 12 insertions, 2 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9ea6d1953765..bec6243b6965 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1361,8 +1361,7 @@ static int __split_huge_page_map(struct page *page,
                  * SMP TLB and finally we write the non-huge version
                  * of the pmd entry with pmd_populate.
                  */
-                set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd));
-                flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+                pmdp_invalidate(vma, address, pmd);
                 pmd_populate(mm, pmd, pgtable);
                 ret = 1;
         }
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 29867e083d37..e642627da6b7 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -159,3 +159,14 @@ pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm)
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 #endif
+
+#ifndef __HAVE_ARCH_PMDP_INVALIDATE
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
+                     pmd_t *pmdp)
+{
+        set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(*pmdp));
+        flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif