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-20191220]
[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: x86_64-rhel (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=x86_64 

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 'hv_hot_remove_range':
>> drivers/hv/hv_balloon.c:1109:10: error: implicit declaration of function 'offline_and_remove_memory'; did you mean '__remove_memory'? [-Werror=implicit-function-declaration]
       ret = offline_and_remove_memory(nid, pfn << PAGE_SHIFT,
             ^~~~~~~~~~~~~~~~~~~~~~~~~
             __remove_memory
   cc1: some warnings being treated as errors

vim +1109 drivers/hv/hv_balloon.c

  1059	
  1060	static int hv_hot_remove_range(unsigned int nid, unsigned long start_pfn,
  1061				       unsigned long end_pfn, unsigned long nr_pages,
  1062				       unsigned long *request_index,
  1063				       union dm_mem_page_range *range_array,
  1064				       struct hv_hotadd_state *has)
  1065	{
  1066		unsigned long block_pages = HA_CHUNK;
  1067		unsigned long rm_pages = nr_pages;
  1068		unsigned long pfn;
  1069		int ret;
  1070	
  1071		for (pfn = start_pfn; pfn < end_pfn; pfn += block_pages) {
  1072			struct hv_hotadd_gap *gap;
  1073			int in_gap;
  1074	
  1075			if (*request_index >= MAX_HOT_REMOVE_ENTRIES) {
  1076				struct dm_hot_remove_response *resp =
  1077					(struct dm_hot_remove_response *)
  1078						balloon_up_send_buffer;
  1079	
  1080				/* Flush out all hot-remove ranges. */
  1081				ret = hv_send_hot_remove_response(resp, *request_index,
  1082								  true);
  1083				if (ret)
  1084					return ret;
  1085	
  1086				/* Reset request buffer. */
  1087				memset(resp, 0x00, PAGE_SIZE);
  1088				*request_index = 0;
  1089			}
  1090	
  1091			/*
  1092			 * Memory in hot-add region gaps has been offlined or removed
  1093			 * and so skip it if remove range overlap with gap.
  1094			 */
  1095			if (has) {
  1096				list_for_each_entry(gap, &has->gap_list, list)
  1097					if (!(pfn >= gap->end_pfn ||
  1098					      pfn + block_pages < gap->start_pfn)) {
  1099						in_gap = 1;
  1100						break;
  1101					}
  1102	
  1103				if (in_gap)
  1104					continue;
  1105			}
  1106	
  1107			if (online_section_nr(pfn_to_section_nr(pfn))
  1108			    && is_mem_section_removable(pfn, block_pages)) {
> 1109				ret = offline_and_remove_memory(nid, pfn << PAGE_SHIFT,
  1110						block_pages << PAGE_SHIFT);
  1111				if (ret)
  1112					continue;
  1113	
  1114				range_array[*request_index].finfo.start_page = pfn;
  1115				range_array[*request_index].finfo.page_cnt
  1116						= block_pages;
  1117	
  1118				(*request_index)++;
  1119				nr_pages -= block_pages;
  1120	
  1121				if (!nr_pages)
  1122					break;
  1123			}
  1124		}
  1125	
  1126		return rm_pages - nr_pages;
  1127	}
  1128	

---
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