thp: setup huge zero page on non-write page fault

[can-eth-gw-linux.git] / mm / huge_memory.c

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index ea0e23fd69674e4b42f32edd51b2fff9bb077a87..e1b6f4e13b91a8150d7cc8d3546098ab4fb9b82d 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -733,6 +733,16 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
                        return VM_FAULT_OOM;
                if (unlikely(khugepaged_enter(vma)))
                        return VM_FAULT_OOM;
+               if (!(flags & FAULT_FLAG_WRITE)) {
+                       pgtable_t pgtable;
+                       pgtable = pte_alloc_one(mm, haddr);
+                       if (unlikely(!pgtable))
+                               return VM_FAULT_OOM;
+                       spin_lock(&mm->page_table_lock);
+                       set_huge_zero_page(pgtable, mm, vma, haddr, pmd);
+                       spin_unlock(&mm->page_table_lock);
+                       return 0;
+               }
                page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
                                          vma, haddr, numa_node_id(), 0);
                if (unlikely(!page)) {