[vishal:vv/dax_abi 6/6] drivers/dax/bus.c:1372:22: error: call to undeclared function 'mhp_supports_memmap_on_memory'; 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/vishal/linux.git vv/dax_abi
head:   6a9c721fafa6903e6a18ace2c5401ad674b1367b
commit: 6a9c721fafa6903e6a18ace2c5401ad674b1367b [6/6] dax: add a sysfs knob to control memmap_on_memory behavior
config: i386-buildonly-randconfig-002-20240124 (https://download.01.org/0day-ci/archive/20240124/202401241453.4WP5ruGd-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240124/202401241453.4WP5ruGd-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/202401241453.4WP5ruGd-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/dax/bus.c:1372:22: error: call to undeclared function 'mhp_supports_memmap_on_memory'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
    1372 |         if (val == true && !mhp_supports_memmap_on_memory()) {
         |                             ^
   1 error generated.


vim +/mhp_supports_memmap_on_memory +1372 drivers/dax/bus.c

  1359	
  1360	static ssize_t memmap_on_memory_store(struct device *dev,
  1361					      struct device_attribute *attr,
  1362					      const char *buf, size_t len)
  1363	{
  1364		struct dev_dax *dev_dax = to_dev_dax(dev);
  1365		bool val;
  1366		int rc;
  1367	
  1368		rc = kstrtobool(buf, &val);
  1369		if (rc)
  1370			return rc;
  1371	
> 1372		if (val == true && !mhp_supports_memmap_on_memory()) {
  1373			dev_dbg(dev, "memmap_on_memory is not available\n");
  1374			return -EOPNOTSUPP;
  1375		}
  1376	
  1377		rc = down_write_killable(&dax_dev_rwsem);
  1378		if (rc)
  1379			return rc;
  1380	
  1381		if (dev_dax->memmap_on_memory != val && dev->driver &&
  1382		    to_dax_drv(dev->driver)->type == DAXDRV_KMEM_TYPE) {
  1383			up_write(&dax_dev_rwsem);
  1384			return -EBUSY;
  1385		}
  1386	
  1387		dev_dax->memmap_on_memory = val;
  1388		up_write(&dax_dev_rwsem);
  1389	
  1390		return len;
  1391	}
  1392	static DEVICE_ATTR_RW(memmap_on_memory);
  1393	

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