[PATCH] mm/slob: Remove unnecessary page_mapcount_reset() function call

[Hyeonggon Yoo <42.hyeyoo@gmail.com>]

After commit f1ac9059ca34 ("mm/sl*b: Differentiate struct slab fields
by sl*b implementations"), we can reorder fields of struct slab
depending on slab allocator.

For now, page_mapcount_reset() is called because page->_mapcount and
slab->units have same offset. But this is not necessary for
struct slab. Use unused field for units instead.

Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
---
 mm/slab.h | 4 ++--
 mm/slob.c | 1 -
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/mm/slab.h b/mm/slab.h
index 90d7fceba470..dd0480149d38 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -50,8 +50,8 @@ struct slab {
 	struct list_head slab_list;
 	void * __unused_1;
 	void *freelist;		/* first free block */
-	void * __unused_2;
-	int units;
+	long units;
+	unsigned int __unused_2;
 
 #else
 #error "Unexpected slab allocator configured"
diff --git a/mm/slob.c b/mm/slob.c
index 39b651b3e6e7..7b2d2c7d69cc 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -404,7 +404,6 @@ static void slob_free(void *block, int size)
 			clear_slob_page_free(sp);
 		spin_unlock_irqrestore(&slob_lock, flags);
 		__ClearPageSlab(slab_page(sp));
-		page_mapcount_reset(slab_page(sp));
 		slob_free_pages(b, 0);
 		return;
 	}
-- 
2.30.2