Re: [PATCH v3 09/20] mm: swap: allocate a virtual swap slot for each swapped out page

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

Hi Nhat,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.19]
[cannot apply to akpm-mm/mm-everything tj-cgroup/for-next tip/smp/core next-20260205]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Nhat-Pham/swap-rearrange-the-swap-header-file/20260209-065842
base:   linus/master
patch link:    https://lore.kernel.org/r/20260208215839.87595-10-nphamcs%40gmail.com
patch subject: [PATCH v3 09/20] mm: swap: allocate a virtual swap slot for each swapped out page
config: s390-randconfig-r134-20260209 (https://download.01.org/0day-ci/archive/20260210/202602100110.Au8uHgc8-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 14.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260210/202602100110.Au8uHgc8-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/202602100110.Au8uHgc8-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> mm/vswap.c:653:9: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected void const [noderef] __percpu *__vpp_verify @@     got struct local_lock_t * @@
   mm/vswap.c:653:9: sparse:     expected void const [noderef] __percpu *__vpp_verify
   mm/vswap.c:653:9: sparse:     got struct local_lock_t *
>> mm/vswap.c:653:9: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected void const [noderef] __percpu *__vpp_verify @@     got struct local_lock_t * @@
   mm/vswap.c:653:9: sparse:     expected void const [noderef] __percpu *__vpp_verify
   mm/vswap.c:653:9: sparse:     got struct local_lock_t *
   mm/vswap.c:665:9: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected void const [noderef] __percpu *__vpp_verify @@     got struct local_lock_t * @@
   mm/vswap.c:665:9: sparse:     expected void const [noderef] __percpu *__vpp_verify
   mm/vswap.c:665:9: sparse:     got struct local_lock_t *
   mm/vswap.c:665:9: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected void const [noderef] __percpu *__vpp_verify @@     got struct local_lock_t * @@
   mm/vswap.c:665:9: sparse:     expected void const [noderef] __percpu *__vpp_verify
   mm/vswap.c:665:9: sparse:     got struct local_lock_t *
   mm/vswap.c:182:36: sparse: sparse: context imbalance in 'vswap_iter' - unexpected unlock
   mm/vswap.c:284:17: sparse: sparse: context imbalance in 'vswap_alloc' - different lock contexts for basic block
   mm/vswap.c:413:19: sparse: sparse: context imbalance in 'vswap_free' - unexpected unlock
   mm/vswap.c: note: in included file (through include/linux/rbtree.h, include/linux/mm_types.h, include/linux/mmzone.h, ...):
   include/linux/rcupdate.h:897:25: sparse: sparse: context imbalance in 'folio_alloc_swap' - unexpected unlock
   mm/vswap.c:570:9: sparse: sparse: context imbalance in 'swp_entry_to_swp_slot' - unexpected unlock

vim +653 mm/vswap.c

   643	
   644	static int vswap_cpu_dead(unsigned int cpu)
   645	{
   646		struct percpu_vswap_cluster *percpu_cluster;
   647		struct vswap_cluster *cluster;
   648		int order;
   649	
   650		percpu_cluster = per_cpu_ptr(&percpu_vswap_cluster, cpu);
   651	
   652		rcu_read_lock();
 > 653		local_lock(&percpu_cluster->lock);
   654		for (order = 0; order < SWAP_NR_ORDERS; order++) {
   655			cluster = percpu_cluster->clusters[order];
   656			if (cluster) {
   657				percpu_cluster->clusters[order] = NULL;
   658				spin_lock(&cluster->lock);
   659				cluster->cached = false;
   660				if (refcount_dec_and_test(&cluster->refcnt))
   661					vswap_cluster_free(cluster);
   662				spin_unlock(&cluster->lock);
   663			}
   664		}
   665		local_unlock(&percpu_cluster->lock);
   666		rcu_read_unlock();
   667	
   668		return 0;
   669	}
   670	

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