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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 6 deletions

diff --git a/mm/highmem.c b/mm/highmem.c
index 2576a7118981..f0f0f1d5e691 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -328,7 +328,6 @@ 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
@@ -395,11 +394,9 @@ 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;
@@ -413,9 +410,7 @@ 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;
                         }
                 }
@@ -438,7 +433,6 @@ 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) */