linux-kernel - [PATCH RESEND 3/3] mm/zsmalloc: remove unused zspage->isolated

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Message-Id: <20240219-b4-szmalloc-migrate-v1-3-fc21039bed7b@linux.dev>
Date: Tue, 20 Feb 2024 11:37:00 +0000
From: Chengming Zhou <chengming.zhou@...ux.dev>
To: hannes@...xchg.org, Sergey Senozhatsky <senozhatsky@...omium.org>, Minchan Kim <minchan@...nel.org>,
 Andrew Morton <akpm@...ux-foundation.org>, nphamcs@...il.com, yosryahmed@...gle.com
Cc: linux-mm@...ck.org, Chengming Zhou <zhouchengming@...edance.com>, linux-kernel@...r.kernel.org
Subject: [PATCH RESEND 3/3] mm/zsmalloc: remove unused zspage->isolated

From: Chengming Zhou <zhouchengming@...edance.com>

The zspage->isolated is not used anywhere, we don't need to maintain it,
which needs to hold the heavy pool lock to update it, so just remove it.

Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
---
 mm/zsmalloc.c | 32 --------------------------------
 1 file changed, 32 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index f2ae7d4c6f21..a48f4651d143 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -116,7 +116,6 @@
 #define HUGE_BITS	1
 #define FULLNESS_BITS	4
 #define CLASS_BITS	8
-#define ISOLATED_BITS	5
 #define MAGIC_VAL_BITS	8
 
 #define MAX(a, b) ((a) >= (b) ? (a) : (b))
@@ -246,7 +245,6 @@ struct zspage {
 		unsigned int huge:HUGE_BITS;
 		unsigned int fullness:FULLNESS_BITS;
 		unsigned int class:CLASS_BITS + 1;
-		unsigned int isolated:ISOLATED_BITS;
 		unsigned int magic:MAGIC_VAL_BITS;
 	};
 	unsigned int inuse;
@@ -1732,17 +1730,6 @@ static void migrate_write_unlock(struct zspage *zspage)
 }
 
 #ifdef CONFIG_COMPACTION
-/* Number of isolated subpage for *page migration* in this zspage */
-static void inc_zspage_isolation(struct zspage *zspage)
-{
-	zspage->isolated++;
-}
-
-static void dec_zspage_isolation(struct zspage *zspage)
-{
-	VM_BUG_ON(zspage->isolated == 0);
-	zspage->isolated--;
-}
 
 static const struct movable_operations zsmalloc_mops;
 
@@ -1771,21 +1758,12 @@ static void replace_sub_page(struct size_class *class, struct zspage *zspage,
 
 static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
 {
-	struct zs_pool *pool;
-	struct zspage *zspage;
-
 	/*
 	 * Page is locked so zspage couldn't be destroyed. For detail, look at
 	 * lock_zspage in free_zspage.
 	 */
 	VM_BUG_ON_PAGE(PageIsolated(page), page);
 
-	zspage = get_zspage(page);
-	pool = zspage->pool;
-	spin_lock(&pool->lock);
-	inc_zspage_isolation(zspage);
-	spin_unlock(&pool->lock);
-
 	return true;
 }
 
@@ -1850,7 +1828,6 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	kunmap_atomic(s_addr);
 
 	replace_sub_page(class, zspage, newpage, page);
-	dec_zspage_isolation(zspage);
 	/*
 	 * Since we complete the data copy and set up new zspage structure,
 	 * it's okay to release the pool's lock.
@@ -1872,16 +1849,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 
 static void zs_page_putback(struct page *page)
 {
-	struct zs_pool *pool;
-	struct zspage *zspage;
-
 	VM_BUG_ON_PAGE(!PageIsolated(page), page);
-
-	zspage = get_zspage(page);
-	pool = zspage->pool;
-	spin_lock(&pool->lock);
-	dec_zspage_isolation(zspage);
-	spin_unlock(&pool->lock);
 }
 
 static const struct movable_operations zsmalloc_mops = {

-- 
b4 0.10.1