else
len = iov_iter_zero(max - pos, iter);
- if (!len)
+ if (!len) {
+ retval = -EFAULT;
break;
+ }
pos += len;
addr += len;
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;