[RFC 6/8] mm: Make VM_CDM marked VMAs non migratable

[Anshuman Khandual <khandual@linux.vnet.ibm.com>]

Auto NUMA does migratability check on any given VMA before scanning it for
marking purpose. For now if the coherent device memory has been faulted in
or migrated into a process VMA, it should not be part of the auto NUMA
migration scheme. The check is based on VM_CDM flag.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
---
 include/linux/mempolicy.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 5e5b296..09d4b70 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -171,9 +171,26 @@ extern int mpol_parse_str(char *str, struct mempolicy **mpol);
 
 extern void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol);
 
+#ifdef CONFIG_COHERENT_DEVICE
+static bool is_cdm_vma(struct vm_area_struct *vma)
+{
+	if (vma->vm_flags & VM_CDM)
+		return true;
+	return false;
+}
+#else
+static bool is_cdm_vma(struct vm_area_struct *vma)
+{
+	return false;
+}
+#endif
+
 /* Check if a vma is migratable */
 static inline bool vma_migratable(struct vm_area_struct *vma)
 {
+	if (is_cdm_vma(vma))
+		return false;
+
 	if (vma->vm_flags & (VM_IO | VM_PFNMAP))
 		return false;
 
-- 
2.1.0