Re: [PATCH -next] mm/mmap_lock: fix warning when CONFIG_TRACING is not defined

[Matthew Wilcox]

On Mon, May 31, 2021 at 09:55:27AM +0800, Bixuan Cui wrote:
> Fix the warning: [-Wunused-function]
> mm/mmap_lock.c:157:20: warning: ‘get_mm_memcg_path’ defined but not used
>  static const char *get_mm_memcg_path(struct mm_struct *mm)
>                     ^~~~~~~~~~~~~~~~~

That seems like the wrong way to fix the warning.  Why not put it
under an appropriate ifdef?

> Signed-off-by: Bixuan Cui <cuibixuan@xxxxxxxxxx>
> ---
>  mm/mmap_lock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c
> index 03ee85c696ef..ec7899b08690 100644
> --- a/mm/mmap_lock.c
> +++ b/mm/mmap_lock.c
> @@ -154,7 +154,7 @@ static inline void put_memcg_path_buf(void)
>   * The caller must call put_memcg_path_buf() once the buffer is no longer
>   * needed. This must be done while preemption is still disabled.
>   */
> -static const char *get_mm_memcg_path(struct mm_struct *mm)
> +static const char __maybe_unused *get_mm_memcg_path(struct mm_struct *mm)
>  {
>  	char *buf = NULL;
>  	struct mem_cgroup *memcg = get_mem_cgroup_from_mm(mm);
> -- 
> 2.17.1
> 
>