linux-kernel - [PATCH] mm: disable numa migration faults for dax vmas

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Date:   Fri, 11 Nov 2016 20:21:41 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     akpm@...ux-foundation.org
Cc:     Michal Hocko <mhocko@...e.com>, linux-nvdimm@...ts.01.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: [PATCH] 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.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 include/linux/mempolicy.h |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 5e5b2969d931..d72c691afaa6 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 +178,9 @@ static inline bool vma_migratable(struct vm_area_struct *vma)
 	if (vma->vm_flags & (VM_IO | VM_PFNMAP))
 		return false;
 
+	if (vma_is_dax(vma))
+		return false;
+
 #ifndef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
 	if (vma->vm_flags & VM_HUGETLB)
 		return false;