1 files changed, 4 insertions, 0 deletions

diff --git a/fs/dax.c b/fs/dax.c
index d1e5cb7311a1..43671b68220e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -541,6 +541,10 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
         unsigned long pfn;
         int result = 0;
 
+        /* dax pmd mappings are broken wrt gup and fork */
+        if (!IS_ENABLED(CONFIG_FS_DAX_PMD))
+                return VM_FAULT_FALLBACK;
+
         /* Fall back to PTEs if we're going to COW */
         if (write && !(vma->vm_flags & VM_SHARED))
                 return VM_FAULT_FALLBACK;