[PATCH RESEND 3/3] mm/zsmalloc: remove get_zspage_mapping()

Chengming Zhou
2024-02-20T11:44:46Z

From: Chengming Zhou <zhouchengming@bytedance.com>

Actually we seldom use the class_idx returned from get_zspage_mapping(),
only the zspage->fullness is useful, just use zspage->fullness to remove
this helper.

Note zspage->fullness is not stable outside pool->lock, remove redundant
"VM_BUG_ON(fullness != ZS_INUSE_RATIO_0)" in async_free_zspage() since
we already have the same VM_BUG_ON() in __free_zspage(), which is safe to
access zspage->fullness with pool->lock held.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
mm/zsmalloc.c | 28 ++++------------------------
1 file changed, 4 insertions(+), 24 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index c39fac9361d7..63ec385cd670 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -470,16 +470,6 @@ static inline void set_freeobj(struct zspage *zspage, unsigned int obj)
zspage->freeobj = obj;
}

-static void get_zspage_mapping(struct zspage *zspage,
- unsigned int *class_idx,
- int *fullness)
-{
- BUG_ON(zspage->magic != ZSPAGE_MAGIC);
-
- *fullness = zspage->fullness;
- *class_idx = zspage->class;
-}
-
static struct size_class *zspage_class(struct zs_pool *pool,
struct zspage *zspage)
{
@@ -708,12 +698,10 @@ static void remove_zspage(struct size_class *class, struct zspage *zspage)
*/
static int fix_fullness_group(struct size_class *class, struct zspage *zspage)
{
- int class_idx;
- int currfg, newfg;
+ int newfg;

- get_zspage_mapping(zspage, &class_idx, &currfg);
newfg = get_fullness_group(class, zspage);
- if (newfg == currfg)
+ if (newfg == zspage->fullness)
goto out;

remove_zspage(class, zspage);
@@ -835,15 +823,11 @@ static void __free_zspage(struct zs_pool *pool, struct size_class *class,
struct zspage *zspage)
{
struct page *page, *next;
- int fg;
- unsigned int class_idx;
-
- get_zspage_mapping(zspage, &class_idx, &fg);

assert_spin_locked(&pool->lock);

VM_BUG_ON(get_zspage_inuse(zspage));
- VM_BUG_ON(fg != ZS_INUSE_RATIO_0);
+ VM_BUG_ON(zspage->fullness != ZS_INUSE_RATIO_0);

next = page = get_first_page(zspage);
do {
@@ -1857,8 +1841,6 @@ static void async_free_zspage(struct work_struct *work)
{
int i;
struct size_class *class;
- unsigned int class_idx;
- int fullness;
struct zspage *zspage, *tmp;
LIST_HEAD(free_pages);
struct zs_pool *pool = container_of(work, struct zs_pool,
@@ -1879,10 +1861,8 @@ static void async_free_zspage(struct work_struct *work)
list_del(&zspage->list);
lock_zspage(zspage);

- get_zspage_mapping(zspage, &class_idx, &fullness);
- VM_BUG_ON(fullness != ZS_INUSE_RATIO_0);
- class = pool->size_class[class_idx];
spin_lock(&pool->lock);
+ class = zspage_class(pool, zspage);
__free_zspage(pool, class, zspage);
spin_unlock(&pool->lock);
}

--
b4 0.10.1