mm: disable numa migration faults for dax vmas
Mark dax vmas as not migratable to exclude them from task_numa_work().
This is especially relevant for device-dax which wants to ensure
predictable access latency and not incur periodic faults.
[akpm@linux-foundation.org: add comment]
Link: http://lkml.kernel.org/r/147892450132.22062.16875659431109209179.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 5e5b296..5f4d828 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -7,6 +7,7 @@
#include <linux/mmzone.h>
+#include <linux/dax.h>
#include <linux/slab.h>
#include <linux/rbtree.h>
#include <linux/spinlock.h>
@@ -177,6 +178,13 @@
if (vma->vm_flags & (VM_IO | VM_PFNMAP))
return false;
+ /*
+ * DAX device mappings require predictable access latency, so avoid
+ * incurring periodic faults.
+ */
+ if (vma_is_dax(vma))
+ return false;
+
#ifndef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
if (vma->vm_flags & VM_HUGETLB)
return false;