The quilt patch titled
Subject: mm: zswap: fix pool refcount bug around shrink_worker()
has been removed from the -mm tree. Its filename was
mm-zswap-fix-pool-refcount-bug-around-shrink_worker.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: zswap: fix pool refcount bug around shrink_worker()
Date: Fri, 6 Oct 2023 12:00:24 -0400
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.
Link: https://lkml.kernel.org/r/20231006160024.170748-1-hannes@xxxxxxxxxxx
Fixes: 45190f01dd40 ("mm/zswap.c: add allocation hysteresis if pool limit is hit")
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reported-by: Chris Mason <clm@xxxxxx>
Acked-by: Nhat Pham <nphamcs@xxxxxxxxx>
Cc: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
Cc: Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [5.6+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zswap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/mm/zswap.c~mm-zswap-fix-pool-refcount-bug-around-shrink_worker
+++ a/mm/zswap.c
@@ -1383,8 +1383,8 @@ reject:
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;
}
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
