Re: [akpm-mm:mm-new 323/362] mm/memcontrol-v1.c:651:31: error: implicit declaration of function 'swp_cluster_offset'

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 20 May 2026 06:16:25 +0800 kernel test robot <lkp@intel.com> wrote:

> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-new
> head:   ac33089a65a951edf4365b1ff7fbe5b5e8062d06
> commit: dc1675a14ba774891fdf5212b7bedc7f50661862 [323/362] mm/memcg, swap: store cgroup id in cluster table directly
> config: sh-allmodconfig (https://download.01.org/0day-ci/archive/20260520/202605200624.e9eMvkBW-lkp@intel.com/config)
> compiler: sh4-linux-gcc (GCC) 15.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260520/202605200624.e9eMvkBW-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202605200624.e9eMvkBW-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>    mm/memcontrol-v1.c: In function '__memcg1_swapout':
> >> mm/memcontrol-v1.c:651:31: error: implicit declaration of function 'swp_cluster_offset' [-Wimplicit-function-declaration]
>      651 |         __swap_cgroup_set(ci, swp_cluster_offset(folio->swap), nr_entries,
>          |                               ^~~~~~~~~~~~~~~~~~

Thanks.  I added the below to fix the build, but I've no reason to
believe that it's correct.

From: Andrew Morton <akpm@linux-foundation.org>
Subject: mm-memcg-swap-store-cgroup-id-in-cluster-table-directly-fix
Date: Tue May 19 03:23:38 PM PDT 2026

"fix" CONFIG_SWAP=n build

Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swap.h |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/mm/swap.h~mm-memcg-swap-store-cgroup-id-in-cluster-table-directly-fix
+++ a/mm/swap.h
@@ -482,5 +482,11 @@ static inline int swap_zeromap_batch(swp
 {
 	return 0;
 }
+
+static inline unsigned int swp_cluster_offset(swp_entry_t entry)
+{
+	return 0;
+}
+
 #endif /* CONFIG_SWAP */
 #endif /* _MM_SWAP_H */
_