mm: memcg-v1: make mem_cgroup_oom_notify_cb() return void

[PATCH] mm: memcg-v1: make mem_cgroup_oom_notify_cb() return void

Posted by Guopeng Zhang 1 week, 5 days ago

From: Guopeng Zhang <zhangguopeng@kylinos.cn>

Commit 7d74b06f240f ("memcg: use for_each_mem_cgroup") replaced the
mem_cgroup_walk_tree() call in mem_cgroup_oom_notify() with
for_each_mem_cgroup_tree(), but left mem_cgroup_oom_notify_cb() with the
int return type required by the old callback interface.

The function now has a single direct caller and no failure path. Make it
return void.

Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
---
 mm/memcontrol-v1.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index e8b6e1560278..73bea1b5c8dd 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -752,7 +752,7 @@ static int compare_thresholds(const void *a, const void *b)
 	return 0;
 }
 
-static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
+static void mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
 {
 	struct mem_cgroup_eventfd_list *ev;
 
@@ -762,7 +762,6 @@ static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
 		eventfd_signal(ev->eventfd);
 
 	spin_unlock(&memcg_oom_lock);
-	return 0;
 }
 
 static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
-- 
2.43.0

Re: [PATCH] mm: memcg-v1: make mem_cgroup_oom_notify_cb() return void

Posted by Shakeel Butt 1 week, 4 days ago

On Mon, Jul 13, 2026 at 05:37:37PM +0800, Guopeng Zhang wrote:
> From: Guopeng Zhang <zhangguopeng@kylinos.cn>
> 
> Commit 7d74b06f240f ("memcg: use for_each_mem_cgroup") replaced the
> mem_cgroup_walk_tree() call in mem_cgroup_oom_notify() with
> for_each_mem_cgroup_tree(), but left mem_cgroup_oom_notify_cb() with the
> int return type required by the old callback interface.
> 
> The function now has a single direct caller and no failure path. Make it
> return void.
> 
> Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>

Acked-by: Shakeel Butt <shakeel.butt@linux.dev>

Re: [PATCH] mm: memcg-v1: make mem_cgroup_oom_notify_cb() return void

Posted by SJ Park 1 week, 4 days ago

On Mon, 13 Jul 2026 17:37:37 +0800 Guopeng Zhang <guopeng.zhang@linux.dev> wrote:

> From: Guopeng Zhang <zhangguopeng@kylinos.cn>
> 
> Commit 7d74b06f240f ("memcg: use for_each_mem_cgroup") replaced the
> mem_cgroup_walk_tree() call in mem_cgroup_oom_notify() with
> for_each_mem_cgroup_tree(), but left mem_cgroup_oom_notify_cb() with the
> int return type required by the old callback interface.
> 
> The function now has a single direct caller and no failure path. Make it
> return void.

Makes sense to me.

> 
> Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>

Reviewed-by: SJ Park <sj@kernel.org>


Thanks,
SJ

[...]

Re: [PATCH] mm: memcg-v1: make mem_cgroup_oom_notify_cb() return void

Posted by Muchun Song 1 week, 5 days ago


> On Jul 13, 2026, at 17:37, Guopeng Zhang <guopeng.zhang@linux.dev> wrote:
> 
> From: Guopeng Zhang <zhangguopeng@kylinos.cn>
> 
> Commit 7d74b06f240f ("memcg: use for_each_mem_cgroup") replaced the
> mem_cgroup_walk_tree() call in mem_cgroup_oom_notify() with
> for_each_mem_cgroup_tree(), but left mem_cgroup_oom_notify_cb() with the
> int return type required by the old callback interface.
> 
> The function now has a single direct caller and no failure path. Make it
> return void.
> 
> Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>

Reviewed-by: Muchun Song <muchun.song@linux.dev>

Re: [PATCH] mm: memcg-v1: make mem_cgroup_oom_notify_cb() return void

Posted by Johannes Weiner 1 week, 5 days ago

On Mon, Jul 13, 2026 at 05:37:37PM +0800, Guopeng Zhang wrote:
> From: Guopeng Zhang <zhangguopeng@kylinos.cn>
> 
> Commit 7d74b06f240f ("memcg: use for_each_mem_cgroup") replaced the
> mem_cgroup_walk_tree() call in mem_cgroup_oom_notify() with
> for_each_mem_cgroup_tree(), but left mem_cgroup_oom_notify_cb() with the
> int return type required by the old callback interface.
> 
> The function now has a single direct caller and no failure path. Make it
> return void.
> 
> Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Re: [PATCH] mm: memcg-v1: make mem_cgroup_oom_notify_cb() return void

Posted by Michal Hocko 1 week, 5 days ago

On Mon 13-07-26 17:37:37, Guopeng Zhang wrote:
> From: Guopeng Zhang <zhangguopeng@kylinos.cn>
> 
> Commit 7d74b06f240f ("memcg: use for_each_mem_cgroup") replaced the
> mem_cgroup_walk_tree() call in mem_cgroup_oom_notify() with
> for_each_mem_cgroup_tree(), but left mem_cgroup_oom_notify_cb() with the
> int return type required by the old callback interface.
> 
> The function now has a single direct caller and no failure path. Make it
> return void.
> 
> Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>

Acked-by: Michal Hocko <mhocko@suse.com>
Thanks!

> ---
>  mm/memcontrol-v1.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
> index e8b6e1560278..73bea1b5c8dd 100644
> --- a/mm/memcontrol-v1.c
> +++ b/mm/memcontrol-v1.c
> @@ -752,7 +752,7 @@ static int compare_thresholds(const void *a, const void *b)
>  	return 0;
>  }
>  
> -static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
> +static void mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
>  {
>  	struct mem_cgroup_eventfd_list *ev;
>  
> @@ -762,7 +762,6 @@ static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
>  		eventfd_signal(ev->eventfd);
>  
>  	spin_unlock(&memcg_oom_lock);
> -	return 0;
>  }
>  
>  static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
> -- 
> 2.43.0

-- 
Michal Hocko
SUSE Labs