[merged mm-stable] mm-zswap-publish-the-initial-pool-with-list_add_rcu.patch removed from -mm tree

[merged mm-stable] mm-zswap-publish-the-initial-pool-with-list_add_rcu.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/zswap: publish the initial pool with list_add_rcu()
has been removed from the -mm tree.  Its filename was
     mm-zswap-publish-the-initial-pool-with-list_add_rcu.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Longlong Xia <xialonglong@kylinos.cn>
Subject: mm/zswap: publish the initial pool with list_add_rcu()
Date: Tue, 8 Sep 2026 09:28:01 +0800

zswap_setup() publishes the pool on the zswap_pools list with a plain
list_add(), but the list is walked by concurrent RCU readers holding
nothing but rcu_read_lock() through zswap_total_pages(), e.g. 
/proc/meminfo and the shrinker count path.

    CPU 0 (writer)                          CPU 1 (reader)
    --------------                          --------------
    zswap_pool_create():
      pool->zs_pool = zs_create_pool(); (1)
    list_add() -> __list_add():
      WRITE_ONCE(zswap_pools.next,
          &pool->list);                (2)   zswap_total_pages():
                                                pool = READ_ONCE(     (a)
                                                    zswap_pools.next);
                                                zs_get_total_pages(   (b)
                                                    pool->zs_pool);

If (2) becomes visible to CPU 1 before (1), CPU 1 finds the pool at (a)
but dereferences a wild pointer at (b).  Publish the node with
list_add_rcu().

Link: https://lore.kernel.org/20260908012801.1864430-1-xialonglong2025@163.com
Fixes: 91cdcd8d624b ("mm: zswap: optimize zswap pool size tracking")
Signed-off-by: Longlong Xia <xialonglong@kylinos.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260906133601.3563324-1-xialonglong2025%40163.com
Acked-by: Yosry Ahmed <yosry@kernel.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Assisted-by: Zcode:GLM-5.3
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
---

 mm/zswap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/zswap.c~mm-zswap-publish-the-initial-pool-with-list_add_rcu
+++ a/mm/zswap.c
@@ -1815,7 +1815,7 @@ static int zswap_setup(void)
 	pool = __zswap_pool_create_fallback();
 	if (pool) {
 		pr_info("loaded using pool %s\n", pool->tfm_name);
-		list_add(&pool->list, &zswap_pools);
+		list_add_rcu(&pool->list, &zswap_pools);
 		zswap_has_pool = true;
 		static_branch_enable(&zswap_ever_enabled);
 	} else {
_

Patches currently in -mm which might be from xialonglong@kylinos.cn are