ksm: cleanup for mm_slots_hash

Use compile-allocated memory instead of dynamic allocated memory for
mm_slots_hash.

Use hash_ptr() instead divisions for bucket calculation.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Izik Eidus <ieidus@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 29 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index 9f2acc998a37..e2ae00458320 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -33,6 +33,7 @@
 #include <linux/mmu_notifier.h>
 #include <linux/swap.h>
 #include <linux/ksm.h>
+#include <linux/hash.h>
 
 #include <asm/tlbflush.h>
 #include "internal.h"
@@ -153,8 +154,9 @@ 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_HEADS 1024
-static struct hlist_head *mm_slots_hash;
+#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];
 
 static struct mm_slot ksm_mm_head = {
         .mm_list = LIST_HEAD_INIT(ksm_mm_head.mm_list),
@@ -269,28 +271,13 @@ static inline void free_mm_slot(struct mm_slot *mm_slot)
         kmem_cache_free(mm_slot_cache, mm_slot);
 }
 
-static int __init mm_slots_hash_init(void)
-{
-        mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head),
-                                GFP_KERNEL);
-        if (!mm_slots_hash)
-                return -ENOMEM;
-        return 0;
-}
-
-static void __init mm_slots_hash_free(void)
-{
-        kfree(mm_slots_hash);
-}
-
 static struct mm_slot *get_mm_slot(struct mm_struct *mm)
 {
         struct mm_slot *mm_slot;
         struct hlist_head *bucket;
         struct hlist_node *node;
 
-        bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
-                                % MM_SLOTS_HASH_HEADS];
+        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;
@@ -303,8 +290,7 @@ static void insert_to_mm_slots_hash(struct mm_struct *mm,
 {
         struct hlist_head *bucket;
 
-        bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
-                                % MM_SLOTS_HASH_HEADS];
+        bucket = &mm_slots_hash[hash_ptr(mm, MM_SLOTS_HASH_SHIFT)];
         mm_slot->mm = mm;
         hlist_add_head(&mm_slot->link, bucket);
 }
@@ -1938,15 +1924,11 @@ static int __init ksm_init(void)
         if (err)
                 goto out;
 
-        err = mm_slots_hash_init();
-        if (err)
-                goto out_free1;
-
         ksm_thread = kthread_run(ksm_scan_thread, NULL, "ksmd");
         if (IS_ERR(ksm_thread)) {
                 printk(KERN_ERR "ksm: creating kthread failed\n");
                 err = PTR_ERR(ksm_thread);
-                goto out_free2;
+                goto out_free;
         }
 
 #ifdef CONFIG_SYSFS
@@ -1954,7 +1936,7 @@ static int __init ksm_init(void)
         if (err) {
                 printk(KERN_ERR "ksm: register sysfs failed\n");
                 kthread_stop(ksm_thread);
-                goto out_free2;
+                goto out_free;
         }
 #else
         ksm_run = KSM_RUN_MERGE;        /* no way for user to start it */
@@ -1970,9 +1952,7 @@ static int __init ksm_init(void)
 #endif
         return 0;
 
-out_free2:
-        mm_slots_hash_free();
-out_free1:
+out_free:
         ksm_slab_free();
 out:
         return err;