linux-kernel - [PATCH] fixup: mm: shrinker: add a secondary array for shrinker_info::{map, nr

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Date:   Thu, 28 Sep 2023 22:15:17 +0800
From:   Qi Zheng <zhengqi.arch@...edance.com>
To:     dan.carpenter@...aro.org, akpm@...ux-foundation.org
Cc:     david@...morbit.com, tkhai@...ru, vbabka@...e.cz,
        roman.gushchin@...ux.dev, djwong@...nel.org, brauner@...nel.org,
        paulmck@...nel.org, tytso@....edu, steven.price@....com,
        cel@...nel.org, senozhatsky@...omium.org, yujie.liu@...el.com,
        gregkh@...uxfoundation.org, muchun.song@...ux.dev,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH] fixup: mm: shrinker: add a secondary array for shrinker_info::{map, nr_deferred}

Dan Carpenter reported the following bug:

```
The patch b6884b5f15cf: "mm: shrinker: add a secondary array for
shrinker_info::{map, nr_deferred}" from Sep 11, 2023 (linux-next),
leads to the following Smatch static checker warning:

	mm/shrinker.c:100 alloc_shrinker_info()
	warn: inconsistent returns '&shrinker_mutex'.
```

To fix it, unlock the &shrinker_rwsem before the call to
free_shrinker_info().

Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
Closes: https://lore.kernel.org/linux-mm/f960ae49-078c-4c00-9516-da31fc1a17d6@moroto.mountain/
Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
---
 mm/shrinker.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/shrinker.c b/mm/shrinker.c
index 893079806553..e9644cda80b5 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -95,6 +95,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg)
 	return ret;
 
 err:
+	up_write(&shrinker_rwsem);
 	free_shrinker_info(memcg);
 	return -ENOMEM;
 }
-- 
2.30.2