mm: move vma_is_anonymous check within pmd_move_must_withdraw

Independent of whether the vma is for anonymous memory, some arches like
ppc64 would like to override pmd_move_must_withdraw().

One option is to encapsulate the vma_is_anonymous() check for general
architectures inside pmd_move_must_withdraw() so that is always called
and architectures that need unconditional overriding can override this
function.  ppc64 needs to override the function when the MMU is
configured to use hash PTE's.

[bsingharora@gmail.com: reworked changelog]
Link: http://lkml.kernel.org/r/20161113150025.17942-1-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 16 insertions, 2 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 26fd1161ca85..b54044c21076 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1429,6 +1429,21 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
         return 1;
 }
 
+#ifndef pmd_move_must_withdraw
+static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
+                                         spinlock_t *old_pmd_ptl,
+                                         struct vm_area_struct *vma)
+{
+        /*
+         * With split pmd lock we also need to move preallocated
+         * PTE page table if new_pmd is on different PMD page table.
+         *
+         * We also don't deposit and withdraw tables for file pages.
+         */
+        return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
+}
+#endif
+
 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
                   unsigned long new_addr, unsigned long old_end,
                   pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush)
@@ -1466,8 +1481,7 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
                         force_flush = true;
                 VM_BUG_ON(!pmd_none(*new_pmd));
 
-                if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
-                                vma_is_anonymous(vma)) {
+                if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
                         pgtable_t pgtable;
                         pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
                         pgtable_trans_huge_deposit(mm, new_pmd, pgtable);