mm, highmem: remove useless pool_lock

The pool_lock protects the page_address_pool from concurrent access.  But,
access to the page_address_pool is already protected by kmap_lock.  So
remove it.

Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kin <minchan@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/highmem.c b/mm/highmem.c
index 017ccccfb4aa2800b2b9125840ce267c1a7bed23..63083a2803ffd04e59d5e647740f8f9cff196da3 100644 (file)
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -329,7 +329,6 @@ struct page_address_map {
  * page_address_map freelist, allocated from page_address_maps.
  */
 static struct list_head page_address_pool;     /* freelist */
-static spinlock_t pool_lock;                   /* protects page_address_pool */
 
 /*
  * Hash table bucket
@@ -396,11 +395,9 @@ void set_page_address(struct page *page, void *virtual)
        if (virtual) {          /* Add */
                BUG_ON(list_empty(&page_address_pool));
 
-               spin_lock_irqsave(&pool_lock, flags);
                pam = list_entry(page_address_pool.next,
                                struct page_address_map, list);
                list_del(&pam->list);
-               spin_unlock_irqrestore(&pool_lock, flags);
 
                pam->page = page;
                pam->virtual = virtual;
@@ -414,9 +411,7 @@ void set_page_address(struct page *page, void *virtual)
                        if (pam->page == page) {
                                list_del(&pam->list);
                                spin_unlock_irqrestore(&pas->lock, flags);
-                               spin_lock_irqsave(&pool_lock, flags);
                                list_add_tail(&pam->list, &page_address_pool);
-                               spin_unlock_irqrestore(&pool_lock, flags);
                                goto done;
                        }
                }
@@ -439,7 +434,6 @@ void __init page_address_init(void)
                INIT_LIST_HEAD(&page_address_htable[i].lh);
                spin_lock_init(&page_address_htable[i].lock);
        }
-       spin_lock_init(&pool_lock);
 }
 
 #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */