FAILED: patch "[PATCH] mm: zswap: fix pool refcount bug around shrink_worker()" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 969d63e1af3b3abe35a49b08218f3125131ac32f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023102756-untainted-stinging-5142@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 969d63e1af3b3abe35a49b08218f3125131ac32f Mon Sep 17 00:00:00 2001
From: Johannes Weiner <[email protected]>
Date: Fri, 6 Oct 2023 12:00:24 -0400
Subject: [PATCH] mm: zswap: fix pool refcount bug around shrink_worker()

When a zswap store fails due to the limit, it acquires a pool reference and queues the shrinker. When the shrinker runs, it drops the reference. However, there can be multiple store attempts before the shrinker wakes up and runs once. This results in reference leaks and eventual saturation warnings for the pool refcount.

Fix this by dropping the reference again when the shrinker is already queued. This ensures one reference per shrinker run.

index 083c693602b8..37d2b1cb2ecb 100644
@@ -1383,8 +1383,8 @@ bool zswap_store(struct folio *folio)
 
 shrink:
 	pool = zswap_pool_last_get();
-	if (pool)
-		queue_work(shrink_wq, &pool->shrink_work);
+	if (pool && !queue_work(shrink_wq, &pool->shrink_work))
+		zswap_pool_put(pool);
 	goto reject;
 }