2023-09-28 19:39:31

by Qi Zheng

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 <[email protected]>
Closes: https://lore.kernel.org/linux-mm/[email protected]/
Signed-off-by: Qi Zheng <[email protected]>
---
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

2023-09-29 02:54:14

by Qi Zheng

Subject: Re: [PATCH] fixup: mm: shrinker: add a secondary array for shrinker_info::{map, nr_deferred}

Hi Andrew,

After applying this fix patch, the following modifications also need to
be applied to the "[PATCH v6 45/45] mm: shrinker: convert shrinker_rwsem
to mutex".

diff --git a/mm/shrinker.c b/mm/shrinker.c
index 6857cbb520ea..dd91eab43ed3 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -96,7 +96,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg)
return ret;

err:
- up_write(&shrinker_rwsem);
+ mutex_unlock(&shrinker_mutex);
free_shrinker_info(memcg);
return -ENOMEM;
}

Or do I need to resend the entire patch set? If yes please let me know.

Thanks,
Qi

On 2023/9/28 22:15, Qi Zheng wrote:
> 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 <[email protected]>
> Closes: https://lore.kernel.org/linux-mm/[email protected]/
> Signed-off-by: Qi Zheng <[email protected]>
> ---
> 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;
> }