[PATCH] mm: memcontrol: fix an unused-function warning

[PATCH] mm: memcontrol: fix an unused-function warning

[Arnd Bergmann]

On NOMMU kernels without CONFIG_MEMCG_KMEM, we now get a harmless
warning about an unused function:

mm/memcontrol.c:2595:13: error: unused function 'cancel_charge' [-Werror,-Wunused-function]

Hide this function in a matching #ifdef.

Fixes: 5bd144bf764c ("mm: memcontrol: drop unused try/commit/cancel charge API")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 mm/memcontrol.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f14da7a7348b..7bfca0abb8e1 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2592,6 +2592,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
 	return 0;
 }
 
+#if defined(CONFIG_MEMCG_KMEM) || defined(CONFIG_MMU)
 static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
 {
 	if (mem_cgroup_is_root(memcg))
@@ -2603,6 +2604,7 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
 
 	css_put_many(&memcg->css, nr_pages);
 }
+#endif
 
 static void commit_charge(struct page *page, struct mem_cgroup *memcg)
 {
-- 
2.26.2

Re: [PATCH] mm: memcontrol: fix an unused-function warning

[Johannes Weiner]

On Thu, May 28, 2020 at 11:56:26AM +0200, Arnd Bergmann wrote:
> On NOMMU kernels without CONFIG_MEMCG_KMEM, we now get a harmless
> warning about an unused function:
> 
> mm/memcontrol.c:2595:13: error: unused function 'cancel_charge' [-Werror,-Wunused-function]
> 
> Hide this function in a matching #ifdef.
> 
> Fixes: 5bd144bf764c ("mm: memcontrol: drop unused try/commit/cancel charge API")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

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

Thanks Arnd!

Re: [PATCH] mm: memcontrol: fix an unused-function warning

[Michal Hocko]

On Thu 28-05-20 11:56:26, Arnd Bergmann wrote:
> On NOMMU kernels without CONFIG_MEMCG_KMEM, we now get a harmless
> warning about an unused function:
> 
> mm/memcontrol.c:2595:13: error: unused function 'cancel_charge' [-Werror,-Wunused-function]
> 
> Hide this function in a matching #ifdef.
> 
> Fixes: 5bd144bf764c ("mm: memcontrol: drop unused try/commit/cancel charge API")

This is a linux-next sha1 which is not valid anymore. I would just drop
the tag.

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

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

Thanks!
> ---
>  mm/memcontrol.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index f14da7a7348b..7bfca0abb8e1 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2592,6 +2592,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
>  	return 0;
>  }
>  
> +#if defined(CONFIG_MEMCG_KMEM) || defined(CONFIG_MMU)
>  static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
>  {
>  	if (mem_cgroup_is_root(memcg))
> @@ -2603,6 +2604,7 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
>  
>  	css_put_many(&memcg->css, nr_pages);
>  }
> +#endif
>  
>  static void commit_charge(struct page *page, struct mem_cgroup *memcg)
>  {
> -- 
> 2.26.2
> 

-- 
Michal Hocko
SUSE Labs