[RFC PATCH 1/4] mm/mempolicy: Expose policy_nodemask() in include/linux/mempolicy.h

[Bijan Tabatabai <bijan311@gmail.com>]

From: Bijan Tabatabai <bijantabatab@micron.com>

This patch is to allow DAMON to call policy_nodemask() so it can
determine where to place a page for interleaving.

Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
---
 include/linux/mempolicy.h | 9 +++++++++
 mm/mempolicy.c            | 4 +---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 0fe96f3ab3ef..e96bf493ff7a 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -133,6 +133,8 @@ struct mempolicy *__get_vma_policy(struct vm_area_struct *vma,
 struct mempolicy *get_vma_policy(struct vm_area_struct *vma,
 		unsigned long addr, int order, pgoff_t *ilx);
 bool vma_policy_mof(struct vm_area_struct *vma);
+nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *pol,
+		pgoff_t ilx, int *nid);
 
 extern void numa_default_policy(void);
 extern void numa_policy_init(void);
@@ -232,6 +234,13 @@ static inline struct mempolicy *get_vma_policy(struct vm_area_struct *vma,
 	return NULL;
 }
 
+static inline nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *pol,
+				pgoff_t ilx, int *nid)
+{
+	*nid = NUMA_NO_NODE;
+	return NULL;
+}
+
 static inline int
 vma_dup_policy(struct vm_area_struct *src, struct vm_area_struct *dst)
 {
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 3b1dfd08338b..54f539497e20 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -596,8 +596,6 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
 
 static bool migrate_folio_add(struct folio *folio, struct list_head *foliolist,
 				unsigned long flags);
-static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *pol,
-				pgoff_t ilx, int *nid);
 
 static bool strictly_unmovable(unsigned long flags)
 {
@@ -2195,7 +2193,7 @@ static unsigned int interleave_nid(struct mempolicy *pol, pgoff_t ilx)
  * Return a nodemask representing a mempolicy for filtering nodes for
  * page allocation, together with preferred node id (or the input node id).
  */
-static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *pol,
+nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *pol,
 				   pgoff_t ilx, int *nid)
 {
 	nodemask_t *nodemask = NULL;
-- 
2.43.5