Merge tag 'arc-4.4-rc7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

[cascardo/linux.git] / fs / dax.c

diff --git a/fs/dax.c b/fs/dax.c
index d1e5cb7..43671b6 100644 (file)
--- 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;