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From: SeongJae Park <sj@kernel.org>
To: Baoquan He <bhe@redhat.com>
Cc: SeongJae Park <sj@kernel.org>,
	kernel test robot <lkp@intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kemeng Shi <shikemeng@huaweicloud.com>,
	llvm@lists.linux.dev,
	oe-kbuild-all@lists.linux.dev,
	Linux Memory Management List <linux-mm@kvack.org>,
	Tim Chen <tim.c.chen@linux.intel.com>
Subject: Re: [linux-next:master 1753/1936] mm/swapfile.c:1517:20: warning: function 'swap_is_last_ref' is not needed and will not be emitted
Date: Wed,  9 Apr 2025 17:26:27 -0700
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Hi Baoquan,

On Thu, 10 Apr 2025 06:45:45 +0800 Baoquan He <bhe@redhat.com> wrote:

[...]
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 2887ed5d34cc..08b52346cc39 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1539,7 +1539,7 @@ static bool swap_entries_put_map_nr(struct swap_info_struct *si,
>   * Drop the last ref(1, SWAP_HAS_CACHE or SWAP_MAP_SHMEM) of swap entries,
>   * caller have to ensure all entries belong to the same cgroup and cluster.
>   */
> -static inline bool swap_is_last_ref(unsigned char count)
> +static inline bool __maybe_unused swap_is_last_ref(unsigned char count)
>  {
>  	return (count == SWAP_HAS_CACHE) || (count == 1) ||
>  	       (count == SWAP_MAP_SHMEM);

I confirmed that this fixes my !CONFIG_DEBUG_VM case build failure on the
latest mm-new.  Thank you for quickly sharing your thought and this fix.


Thanks,
SJ