[akpm-mm:mm-unstable 199/420] mm/memcontrol-v1.c:651:24: error: call to undeclared function 'swp_cluster_offset'; ISO C99 and later do not support implicit function declarations

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
head:   8a74e22643189e0ae339afc91110ddb4cab1941b
commit: 93680c2b51fa1f84fe50800b71140dbd283372b8 [199/420] mm/memcg, swap: store cgroup id in cluster table directly
config: arm-randconfig-004-20260528 (https://download.01.org/0day-ci/archive/20260528/202605281711.bSeZlErK-lkp@intel.com/config)
compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project 9409c07de6378507397ecdb6f05f628f58110112)
rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260528/202605281711.bSeZlErK-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/202605281711.bSeZlErK-lkp@intel.com/

All errors (new ones prefixed by >>):

>> mm/memcontrol-v1.c:651:24: error: call to undeclared function 'swp_cluster_offset'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     651 |         __swap_cgroup_set(ci, swp_cluster_offset(folio->swap), nr_entries,
         |                               ^
   mm/memcontrol-v1.c:721:31: error: call to undeclared function 'swp_cluster_offset'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     721 |         id = __swap_cgroup_clear(ci, swp_cluster_offset(folio->swap),
         |                                      ^
   2 errors generated.


vim +/swp_cluster_offset +651 mm/memcontrol-v1.c

   606	
   607	/**
   608	 * __memcg1_swapout - transfer a memsw charge to swap
   609	 * @folio: folio whose memsw charge to transfer
   610	 * @ci: the locked swap cluster holding the swap entries
   611	 *
   612	 * Transfer the memsw charge of @folio to the swap entry stored in
   613	 * folio->swap.
   614	 *
   615	 * Context: folio must be isolated, unmapped, locked and is just about to
   616	 * be freed, and caller must disable IRQs and hold the swap cluster lock.
   617	 */
   618	void __memcg1_swapout(struct folio *folio, struct swap_cluster_info *ci)
   619	{
   620		struct mem_cgroup *memcg, *swap_memcg;
   621		struct obj_cgroup *objcg;
   622		unsigned int nr_entries;
   623	
   624		VM_WARN_ON_ONCE_FOLIO(!folio_test_swapcache(folio), folio);
   625		VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);
   626		VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
   627		VM_BUG_ON_FOLIO(folio_ref_count(folio), folio);
   628	
   629		if (mem_cgroup_disabled())
   630			return;
   631	
   632		if (!do_memsw_account())
   633			return;
   634	
   635		objcg = folio_objcg(folio);
   636		VM_WARN_ON_ONCE_FOLIO(!objcg, folio);
   637		if (!objcg)
   638			return;
   639	
   640		rcu_read_lock();
   641		memcg = obj_cgroup_memcg(objcg);
   642		/*
   643		 * In case the memcg owning these pages has been offlined and doesn't
   644		 * have an ID allocated to it anymore, charge the closest online
   645		 * ancestor for the swap instead and transfer the memory+swap charge.
   646		 */
   647		nr_entries = folio_nr_pages(folio);
   648		swap_memcg = mem_cgroup_private_id_get_online(memcg, nr_entries);
   649		mod_memcg_state(swap_memcg, MEMCG_SWAP, nr_entries);
   650	
 > 651		__swap_cgroup_set(ci, swp_cluster_offset(folio->swap), nr_entries,
   652				  mem_cgroup_private_id(swap_memcg));
   653	
   654		folio_unqueue_deferred_split(folio);
   655		folio->memcg_data = 0;
   656	
   657		if (!obj_cgroup_is_root(objcg))
   658			page_counter_uncharge(&memcg->memory, nr_entries);
   659	
   660		if (memcg != swap_memcg) {
   661			if (!mem_cgroup_is_root(swap_memcg))
   662				page_counter_charge(&swap_memcg->memsw, nr_entries);
   663			page_counter_uncharge(&memcg->memsw, nr_entries);
   664		}
   665	
   666		/*
   667		 * The caller must hold the swap cluster lock with IRQ off. It is
   668		 * important here to have the interrupts disabled because it is the
   669		 * only synchronisation we have for updating the per-CPU variables.
   670		 */
   671		preempt_disable_nested();
   672		VM_WARN_ON_IRQS_ENABLED();
   673		memcg1_charge_statistics(memcg, -folio_nr_pages(folio));
   674		preempt_enable_nested();
   675		memcg1_check_events(memcg, folio_nid(folio));
   676	
   677		rcu_read_unlock();
   678		obj_cgroup_put(objcg);
   679	}
   680	

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