[PATCH v2 1/2] mm/mm_slot.h: add a helper function mm_slot_remove

[xu.xin16]

From: xu xin <xu.xin16@xxxxxxxxxx>

Both THP and KSM manage per-mm scanning slots using the mm_slot
structure. The slot is kept in a hash table and a list, and removal from
both containers requires the same two operations: hash_del() and
list_del().

Introduce mm_slot_remove() to abstract the common hash_del() + list_del()
sequence used in both khugepaged and KSM.

No functional change is intended.

Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx>
---
 mm/khugepaged.c | 6 ++----
 mm/ksm.c        | 9 +++------
 mm/mm_slot.h    | 5 +++++
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 58e14d1543ec..5f6eb1bd9a67 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -606,8 +606,7 @@ void __khugepaged_exit(struct mm_struct *mm)
 	spin_lock(&khugepaged_mm_lock);
 	slot = mm_slot_lookup(mm_slots_hash, mm);
 	if (slot && khugepaged_scan.mm_slot != slot) {
-		hash_del(&slot->hash);
-		list_del(&slot->mm_node);
+		mm_slot_remove(slot);
 		free = 1;
 	}
 	spin_unlock(&khugepaged_mm_lock);
@@ -1802,8 +1801,7 @@ static void collect_mm_slot(struct mm_slot *slot)

 	if (collapse_test_exit(mm)) {
 		/* free mm_slot */
-		hash_del(&slot->hash);
-		list_del(&slot->mm_node);
+		mm_slot_remove(slot);

 		/*
 		 * Not strictly needed because the mm exited already.
diff --git a/mm/ksm.c b/mm/ksm.c
index 2791ce5bd44b..443dab513da6 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1257,8 +1257,7 @@ static int unmerge_and_remove_all_rmap_items(void)
 				  struct mm_slot, mm_node);
 		ksm_scan.mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot);
 		if (ksm_test_exit(mm)) {
-			hash_del(&mm_slot->slot.hash);
-			list_del(&mm_slot->slot.mm_node);
+			mm_slot_remove(&mm_slot->slot);
 			spin_unlock(&ksm_mmlist_lock);

 			mm_slot_free(mm_slot_cache, mm_slot);
@@ -2772,8 +2771,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page)
 		 * or when all VM_MERGEABLE areas have been unmapped (and
 		 * mmap_lock then protects against race with MADV_MERGEABLE).
 		 */
-		hash_del(&mm_slot->slot.hash);
-		list_del(&mm_slot->slot.mm_node);
+		mm_slot_remove(&mm_slot->slot);
 		spin_unlock(&ksm_mmlist_lock);

 		mm_slot_free(mm_slot_cache, mm_slot);
@@ -3116,8 +3114,7 @@ void __ksm_exit(struct mm_struct *mm)
 	if (ksm_scan.mm_slot == mm_slot)
 		goto unlock;
 	if (!mm_slot->rmap_list) {
-		hash_del(&slot->hash);
-		list_del(&slot->mm_node);
+		mm_slot_remove(slot);
 		easy_to_free = 1;
 	} else {
 		list_move(&slot->mm_node,
diff --git a/mm/mm_slot.h b/mm/mm_slot.h
index 83f18ed1c4bd..5de3e91d86b4 100644
--- a/mm/mm_slot.h
+++ b/mm/mm_slot.h
@@ -52,4 +52,9 @@ static inline void mm_slot_free(struct kmem_cache *cache, void *objp)
 	hash_add(_hashtable, &_mm_slot->hash, (unsigned long)_mm);	       \
 })

+static inline void mm_slot_remove(struct mm_slot *slot)
+{
+	hash_del(&slot->hash);
+	list_del(&slot->mm_node);
+}
 #endif /* _LINUX_MM_SLOT_H */
-- 
2.25.1