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Subject[PATCH 02/15] mm,ksm: use new hashtable implementation
Date
Switch ksm to use the new hashtable implementation. This reduces the amount of
generic unrelated code in the ksm module.

This patch depends on d9b482c ("hashtable: introduce a small and naive
hashtable") which was merged in v3.6.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
mm/ksm.c | 31 +++++++++++++------------------
1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 382d930..e888f54 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -33,7 +33,7 @@
#include <linux/mmu_notifier.h>
#include <linux/swap.h>
#include <linux/ksm.h>
-#include <linux/hash.h>
+#include <linux/hashtable.h>
#include <linux/freezer.h>
#include <linux/oom.h>

@@ -156,9 +156,8 @@ struct rmap_item {
static struct rb_root root_stable_tree = RB_ROOT;
static struct rb_root root_unstable_tree = RB_ROOT;

-#define MM_SLOTS_HASH_SHIFT 10
-#define MM_SLOTS_HASH_HEADS (1 << MM_SLOTS_HASH_SHIFT)
-static struct hlist_head mm_slots_hash[MM_SLOTS_HASH_HEADS];
+#define MM_SLOTS_HASH_BITS 10
+static DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);

static struct mm_slot ksm_mm_head = {
.mm_list = LIST_HEAD_INIT(ksm_mm_head.mm_list),
@@ -275,26 +274,21 @@ static inline void free_mm_slot(struct mm_slot *mm_slot)

static struct mm_slot *get_mm_slot(struct mm_struct *mm)
{
- struct mm_slot *mm_slot;
- struct hlist_head *bucket;
struct hlist_node *node;
+ struct mm_slot *slot;
+
+ hash_for_each_possible(mm_slots_hash, slot, node, link, (unsigned long)mm)
+ if (slot->mm == mm)
+ return slot;

- bucket = &mm_slots_hash[hash_ptr(mm, MM_SLOTS_HASH_SHIFT)];
- hlist_for_each_entry(mm_slot, node, bucket, link) {
- if (mm == mm_slot->mm)
- return mm_slot;
- }
return NULL;
}

static void insert_to_mm_slots_hash(struct mm_struct *mm,
struct mm_slot *mm_slot)
{
- struct hlist_head *bucket;
-
- bucket = &mm_slots_hash[hash_ptr(mm, MM_SLOTS_HASH_SHIFT)];
mm_slot->mm = mm;
- hlist_add_head(&mm_slot->link, bucket);
+ hash_add(mm_slots_hash, &mm_slot->link, (unsigned long)mm);
}

static inline int in_stable_tree(struct rmap_item *rmap_item)
@@ -647,7 +641,7 @@ static int unmerge_and_remove_all_rmap_items(void)
ksm_scan.mm_slot = list_entry(mm_slot->mm_list.next,
struct mm_slot, mm_list);
if (ksm_test_exit(mm)) {
- hlist_del(&mm_slot->link);
+ hash_del(&mm_slot->link);
list_del(&mm_slot->mm_list);
spin_unlock(&ksm_mmlist_lock);

@@ -1392,7 +1386,7 @@ next_mm:
* or when all VM_MERGEABLE areas have been unmapped (and
* mmap_sem then protects against race with MADV_MERGEABLE).
*/
- hlist_del(&slot->link);
+ hash_del(&slot->link);
list_del(&slot->mm_list);
spin_unlock(&ksm_mmlist_lock);

@@ -1559,7 +1553,7 @@ void __ksm_exit(struct mm_struct *mm)
mm_slot = get_mm_slot(mm);
if (mm_slot && ksm_scan.mm_slot != mm_slot) {
if (!mm_slot->rmap_list) {
- hlist_del(&mm_slot->link);
+ hash_del(&mm_slot->link);
list_del(&mm_slot->mm_list);
easy_to_free = 1;
} else {
@@ -2035,6 +2029,7 @@ static int __init ksm_init(void)
*/
hotplug_memory_notifier(ksm_memory_callback, 100);
#endif
+
return 0;

out_free:
--
1.8.0


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