X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=fs%2Fdax.c;h=43671b68220ed968386f5c1ad9067f236fbab67e;hb=45568625feacf13f1450da6b8cec17bf97c5a3fd;hp=d1e5cb7311a1de295ecd4348360a9a9947e71142;hpb=b84da9fa47cf6e8dfd71d673a2f744ec1cac452c;p=firefly-linux-kernel-4.4.55.git

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;