linux-kernel - mm/percpu.c:3007:59: warning: the comparison will always evaluate as 'true' for the address of 'pglist' will never be NULL

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Message-ID: <202207242252.HNteQE9R-lkp@intel.com>
Date:   Sun, 24 Jul 2022 22:17:26 +0800
From:   kernel test robot <lkp@...el.com>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>
Subject: mm/percpu.c:3007:59: warning: the comparison will always evaluate as
 'true' for the address of 'pglist' will never be NULL

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   515f71412bb73ebd7f41f90e1684fc80b8730789
commit: 23f917169ef157aa7a6bf80d8c4aad6f1282852c mm: percpu: add generic pcpu_fc_alloc/free funciton
date:   6 months ago
config: mips-buildonly-randconfig-r003-20220724 (https://download.01.org/0day-ci/archive/20220724/202207242252.HNteQE9R-lkp@intel.com/config)
compiler: mips64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=23f917169ef157aa7a6bf80d8c4aad6f1282852c
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 23f917169ef157aa7a6bf80d8c4aad6f1282852c
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

   mm/percpu.c: In function 'pcpu_fc_alloc':
>> mm/percpu.c:3007:59: warning: the comparison will always evaluate as 'true' for the address of 'pglist' will never be NULL [-Waddress]
    3007 |         if (node == NUMA_NO_NODE || !node_online(node) || !NODE_DATA(node)) {
         |                                                           ^
   In file included from arch/mips/include/asm/mmzone.h:12,
                    from include/linux/mmzone.h:1099,
                    from include/linux/gfp.h:6,
                    from include/linux/mm.h:10,
                    from include/linux/memblock.h:13,
                    from mm/percpu.c:73:
   arch/mips/include/asm/mach-ip27/mmzone.h:19:28: note: 'pglist' declared here
      19 |         struct pglist_data pglist;
         |                            ^~~~~~


vim +3007 mm/percpu.c

  2995	
  2996	static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size, size_t align,
  2997					   pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn)
  2998	{
  2999		const unsigned long goal = __pa(MAX_DMA_ADDRESS);
  3000	#ifdef CONFIG_NUMA
  3001		int node = NUMA_NO_NODE;
  3002		void *ptr;
  3003	
  3004		if (cpu_to_nd_fn)
  3005			node = cpu_to_nd_fn(cpu);
  3006	
> 3007		if (node == NUMA_NO_NODE || !node_online(node) || !NODE_DATA(node)) {
  3008			ptr = memblock_alloc_from(size, align, goal);
  3009			pr_info("cpu %d has no node %d or node-local memory\n",
  3010				cpu, node);
  3011			pr_debug("per cpu data for cpu%d %zu bytes at 0x%llx\n",
  3012				 cpu, size, (u64)__pa(ptr));
  3013		} else {
  3014			ptr = memblock_alloc_try_nid(size, align, goal,
  3015						     MEMBLOCK_ALLOC_ACCESSIBLE,
  3016						     node);
  3017	
  3018			pr_debug("per cpu data for cpu%d %zu bytes on node%d at 0x%llx\n",
  3019				 cpu, size, node, (u64)__pa(ptr));
  3020		}
  3021		return ptr;
  3022	#else
  3023		return memblock_alloc_from(size, align, goal);
  3024	#endif
  3025	}
  3026	

-- 
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