Re: [PATCH] mm: compaction: fix compiler warning when CONFIG_COMPACTION=n

[Vlastimil Babka]

On 3/18/22 14:01, Charan Teja Kalla wrote:
> The below warning is reported when CONFIG_COMPACTION=n:
> 
>    mm/compaction.c:56:27: warning: 'HPAGE_FRAG_CHECK_INTERVAL_MSEC'
> defined but not used [-Wunused-const-variable=]
>       56 | static const unsigned int HPAGE_FRAG_CHECK_INTERVAL_MSEC =
> 500;
>          |                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Fix it by moving 'HPAGE_FRAG_CHECK_INTERVAL_MSEC' under
> CONFIG_COMPACTION defconfig. Also since this is just a 'static const
> int' type, use #define for it.
> 
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Signed-off-by: Charan Teja Kalla <quic_charante@xxxxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

> ---
>  mm/compaction.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index b4e94cd..4d86d04 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -26,6 +26,11 @@
>  #include "internal.h"
>  
>  #ifdef CONFIG_COMPACTION
> +/*
> + * Fragmentation score check interval for proactive compaction purposes.
> + */
> +#define HPAGE_FRAG_CHECK_INTERVAL_MSEC	(500)
> +
>  static inline void count_compact_event(enum vm_event_item item)
>  {
>  	count_vm_event(item);
> @@ -51,11 +56,6 @@ static inline void count_compact_events(enum vm_event_item item, long delta)
>  #define pageblock_end_pfn(pfn)		block_end_pfn(pfn, pageblock_order)
>  
>  /*
> - * Fragmentation score check interval for proactive compaction purposes.
> - */
> -static const unsigned int HPAGE_FRAG_CHECK_INTERVAL_MSEC = 500;
> -
> -/*
>   * Page order with-respect-to which proactive compaction
>   * calculates external fragmentation, which is used as
>   * the "fragmentation score" of a node/zone.