Re: [PATCH v2 2/3] mm,memory_hotplug: Implement numa node notifier

Re: [PATCH v2 2/3] mm,memory_hotplug: Implement numa node notifier

[kernel test robot]

Hi Oscar,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on next-20250409]
[cannot apply to rafael-pm/linux-next rafael-pm/bleeding-edge driver-core/driver-core-testing driver-core/driver-core-next driver-core/driver-core-linus tj-cgroup/for-next linus/master vbabka-slab/for-next v6.15-rc1]
[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/Oscar-Salvador/mm-slub-Do-not-special-case-N_NORMAL-nodes-for-slab_nodes/20250408-164417
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20250408084153.255762-3-osalvador%40suse.de
patch subject: [PATCH v2 2/3] mm,memory_hotplug: Implement numa node notifier
config: arm64-randconfig-001-20250409 (https://download.01.org/0day-ci/archive/20250409/202504092104.MyHeSV43-lkp@intel.com/config)
compiler: clang version 21.0.0git (https://github.com/llvm/llvm-project 92c93f5286b9ff33f27ff694d2dc33da1c07afdd)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250409/202504092104.MyHeSV43-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/202504092104.MyHeSV43-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/base/node.c:115:5: error: redefinition of 'register_node_notifier'
     115 | int register_node_notifier(struct notifier_block *nb)
         |     ^
   include/linux/memory.h:172:19: note: previous definition is here
     172 | static inline int register_node_notifier(struct notifier_block *nb)
         |                   ^
>> drivers/base/node.c:121:6: error: redefinition of 'unregister_node_notifier'
     121 | void unregister_node_notifier(struct notifier_block *nb)
         |      ^
   include/linux/memory.h:176:20: note: previous definition is here
     176 | static inline void unregister_node_notifier(struct notifier_block *nb)
         |                    ^
>> drivers/base/node.c:127:5: error: redefinition of 'node_notify'
     127 | int node_notify(unsigned long val, void *v)
         |     ^
   include/linux/memory.h:179:19: note: previous definition is here
     179 | static inline int node_notify(unsigned long val, void *v)
         |                   ^
   3 errors generated.


vim +/register_node_notifier +115 drivers/base/node.c

   114	
 > 115	int register_node_notifier(struct notifier_block *nb)
   116	{
   117		return blocking_notifier_chain_register(&node_chain, nb);
   118	}
   119	EXPORT_SYMBOL(register_node_notifier);
   120	
 > 121	void unregister_node_notifier(struct notifier_block *nb)
   122	{
   123		blocking_notifier_chain_unregister(&node_chain, nb);
   124	}
   125	EXPORT_SYMBOL(unregister_node_notifier);
   126	
 > 127	int node_notify(unsigned long val, void *v)
   128	{
   129		return blocking_notifier_call_chain(&node_chain, val, v);
   130	}
   131	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v2 2/3] mm,memory_hotplug: Implement numa node notifier

[Oscar Salvador]

On Wed, Apr 09, 2025 at 09:44:52PM +0800, kernel test robot wrote:
> Hi Oscar,
> 
> kernel test robot noticed the following build errors:
... 
> >> drivers/base/node.c:115:5: error: redefinition of 'register_node_notifier'
>      115 | int register_node_notifier(struct notifier_block *nb)
>          |     ^
>    include/linux/memory.h:172:19: note: previous definition is here
>      172 | static inline int register_node_notifier(struct notifier_block *nb)
>          |                   ^
> >> drivers/base/node.c:121:6: error: redefinition of 'unregister_node_notifier'
>      121 | void unregister_node_notifier(struct notifier_block *nb)
>          |      ^
>    include/linux/memory.h:176:20: note: previous definition is here
>      176 | static inline void unregister_node_notifier(struct notifier_block *nb)
>          |                    ^
> >> drivers/base/node.c:127:5: error: redefinition of 'node_notify'
>      127 | int node_notify(unsigned long val, void *v)
>          |     ^
>    include/linux/memory.h:179:19: note: previous definition is here
>      179 | static inline int node_notify(unsigned long val, void *v)
>          |                   ^
>    3 errors generated.

Ah, I see. When CONFIG_MEMORY_HOTPLUG=n those come into play.
That is not a problem for the memory-notify thing because drivers/base/memory.c
gets compiled IFF CONFIG_MEMORY_HOTPLUG=y.
I am thinking two ways to fix this:

 1) Move the code for node-notify to drivers/base/memory.c
 2) Surround those functions within a
 #ifdef CONFIG_MEMORY_HOTPLUG
 ...
 #endif

Thoughts? I lean towards option #2 as it looks cleaner to me:

 diff --git a/drivers/base/node.c b/drivers/base/node.c
 index 182c71dfb5b8..3b084d71888a 100644
 --- a/drivers/base/node.c
 +++ b/drivers/base/node.c
 @@ -110,6 +110,7 @@ static const struct attribute_group *node_access_node_groups[] = {
         NULL,
  };
  
 +#ifdef CONFIG_MEMORY_HOTPLUG
  static BLOCKING_NOTIFIER_HEAD(node_chain);
  
  int register_node_notifier(struct notifier_block *nb)
 @@ -128,6 +129,7 @@ int node_notify(unsigned long val, void *v)
  {
         return blocking_notifier_call_chain(&node_chain, val, v);
  }
 +#endif
  
  static void node_remove_accesses(struct node *node)
  {



-- 
Oscar Salvador
SUSE Labs