+ zsmalloc-add-a-lru-to-zs_pool-to-keep-track-of-zspages-in-lru-order.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: zsmalloc: add a LRU to zs_pool to keep track of zspages in LRU order
has been added to the -mm mm-unstable branch.  Its filename is
     zsmalloc-add-a-lru-to-zs_pool-to-keep-track-of-zspages-in-lru-order.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zsmalloc-add-a-lru-to-zs_pool-to-keep-track-of-zspages-in-lru-order.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Nhat Pham <nphamcs@gmail.com>
Subject: zsmalloc: add a LRU to zs_pool to keep track of zspages in LRU order
Date: Fri, 18 Nov 2022 16:15:34 -0800

This helps determines the coldest zspages as candidates for writeback.

Link: https://lkml.kernel.org/r/20221119001536.2086599-5-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/zsmalloc.c |   34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

--- a/mm/zsmalloc.c~zsmalloc-add-a-lru-to-zs_pool-to-keep-track-of-zspages-in-lru-order
+++ a/mm/zsmalloc.c
@@ -239,6 +239,11 @@ struct zs_pool {
 	/* Compact classes */
 	struct shrinker shrinker;
 
+#ifdef CONFIG_ZPOOL
+	/* List tracking the zspages in LRU order by most recently added object */
+	struct list_head lru;
+#endif
+
 #ifdef CONFIG_ZSMALLOC_STAT
 	struct dentry *stat_dentry;
 #endif
@@ -260,6 +265,12 @@ struct zspage {
 	unsigned int freeobj;
 	struct page *first_page;
 	struct list_head list; /* fullness list */
+
+#ifdef CONFIG_ZPOOL
+	/* links the zspage to the lru list in the pool */
+	struct list_head lru;
+#endif
+
 	struct zs_pool *pool;
 #ifdef CONFIG_COMPACTION
 	rwlock_t lock;
@@ -953,6 +964,9 @@ static void free_zspage(struct zs_pool *
 	}
 
 	remove_zspage(class, zspage, ZS_EMPTY);
+#ifdef CONFIG_ZPOOL
+	list_del(&zspage->lru);
+#endif
 	__free_zspage(pool, class, zspage);
 }
 
@@ -998,6 +1012,10 @@ static void init_zspage(struct size_clas
 		off %= PAGE_SIZE;
 	}
 
+#ifdef CONFIG_ZPOOL
+	INIT_LIST_HEAD(&zspage->lru);
+#endif
+
 	set_freeobj(zspage, 0);
 }
 
@@ -1270,6 +1288,15 @@ void *zs_map_object(struct zs_pool *pool
 	obj_to_location(obj, &page, &obj_idx);
 	zspage = get_zspage(page);
 
+#ifdef CONFIG_ZPOOL
+	/* Move the zspage to front of pool's LRU */
+	if (mm == ZS_MM_WO) {
+		if (!list_empty(&zspage->lru))
+			list_del(&zspage->lru);
+		list_add(&zspage->lru, &pool->lru);
+	}
+#endif
+
 	/*
 	 * migration cannot move any zpages in this zspage. Here, pool->lock
 	 * is too heavy since callers would take some time until they calls
@@ -1988,6 +2015,9 @@ static void async_free_zspage(struct wor
 		VM_BUG_ON(fullness != ZS_EMPTY);
 		class = pool->size_class[class_idx];
 		spin_lock(&pool->lock);
+#ifdef CONFIG_ZPOOL
+		list_del(&zspage->lru);
+#endif
 		__free_zspage(pool, class, zspage);
 		spin_unlock(&pool->lock);
 	}
@@ -2299,6 +2329,10 @@ struct zs_pool *zs_create_pool(const cha
 	 */
 	zs_register_shrinker(pool);
 
+#ifdef CONFIG_ZPOOL
+	INIT_LIST_HEAD(&pool->lru);
+#endif
+
 	return pool;
 
 err:
_

Patches currently in -mm which might be from nphamcs@gmail.com are

zsmalloc-consolidate-zs_pools-migrate_lock-and-size_classs-locks.patch
zsmalloc-add-a-lru-to-zs_pool-to-keep-track-of-zspages-in-lru-order.patch
zsmalloc-add-zpool_ops-field-to-zs_pool-to-store-evict-handlers.patch
zsmalloc-implement-writeback-mechanism-for-zsmalloc.patch