Hi,

[FYI, it's a private test report for your RFC patch.]
[auto build test ERROR on linus/master]
[also build test ERROR on v5.5-rc5 next-20200106]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/lantianyu1986-gmail-com/x86-Hyper-V-Add-Dynamic-memory-hot-remove-function/20200108-055844
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git ae6088216ce4b99b3a4aaaccd2eb2dd40d473d42
config: i386-allyesconfig (attached as .config)
compiler: gcc-7 (Debian 7.5.0-3) 7.5.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   drivers/hv/hv_balloon.c: In function 'hot_remove_req':
   drivers/hv/hv_balloon.c:1481:3: error: implicit declaration of function 'hv_mem_hot_remove'; did you mean 'device_link_remove'? [-Werror=implicit-function-declaration]
      hv_mem_hot_remove(numa_node, page_count);
      ^~~~~~~~~~~~~~~~~
      device_link_remove
   drivers/hv/hv_balloon.c: In function 'balloon_down':
>> drivers/hv/hv_balloon.c:1842:5: error: implicit declaration of function 'process_hot_add'; did you mean '__check_hot_add'? [-Werror=implicit-function-declaration]
        process_hot_add(range_array[i].finfo.start_page,
        ^~~~~~~~~~~~~~~
        __check_hot_add
   cc1: some warnings being treated as errors

vim +1842 drivers/hv/hv_balloon.c

  1821	
  1822	static void balloon_down(union dm_msg_info *msg_info)
  1823	{
  1824		struct dm_unballoon_request *req = msg_info->unballoon_state.request;
  1825		union dm_mem_page_range *range_array = req->range_array;
  1826		struct hv_dynmem_device *dm = &dm_device;
  1827		unsigned int prev_pages_ballooned = dm->num_pages_ballooned;
  1828		int range_count = req->range_count;
  1829		struct dm_unballoon_response resp;
  1830		int i;
  1831	
  1832		for (i = 0; i < range_count; i++) {
  1833			/*
  1834			 * Hyper-V has a bug that send unballoon msg instead
  1835			 * of hot add msg even if there is no balloon msg sent
  1836			 * before. Treat all unballoon msgs as hot add msgs
  1837			 * if hot add capability is enabled.
  1838			 */
  1839			if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG) && do_hot_add) {
  1840				dm->host_specified_ha_region = false;
  1841				dm->num_pages_added +=
> 1842					process_hot_add(range_array[i].finfo.start_page,
  1843					range_array[i].finfo.page_cnt, 0, 0);
  1844			} else {
  1845				free_balloon_pages(dm, &range_array[i]);
  1846				complete(&dm_device.config_event);
  1847			}
  1848		}
  1849	
  1850		if (!do_hot_add)
  1851			pr_debug("Freed %u ballooned pages.\n",
  1852				prev_pages_ballooned - dm->num_pages_ballooned);
  1853	
  1854		if (req->more_pages == 1)
  1855			return;
  1856	
  1857		memset(&resp, 0, sizeof(struct dm_unballoon_response));
  1858		resp.hdr.type = DM_UNBALLOON_RESPONSE;
  1859		resp.hdr.trans_id = atomic_inc_return(&trans_id);
  1860		resp.hdr.size = sizeof(struct dm_unballoon_response);
  1861	
  1862		vmbus_sendpacket(dm_device.dev->channel, &resp,
  1863					sizeof(struct dm_unballoon_response),
  1864					(unsigned long)NULL,
  1865					VM_PKT_DATA_INBAND, 0);
  1866	
  1867		dm->state = DM_INITIALIZED;
  1868	}
  1869	

---
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