Hi Roger,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on xen-tip/linux-next]
[also build test ERROR on linux/master hnaz-linux-mm/master linus/master v5.9-rc3]
[cannot apply to next-20200828]
[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]

url:    https://github.com/0day-ci/linux/commits/Roger-Pau-Monne/xen-balloon-fixes-for-memory-hotplug/20200901-163414
base:   https://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git linux-next
config: x86_64-randconfig-a011-20200901 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project c10e63677f5d20f18010f8f68c631ddc97546f7d)
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
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

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

All errors (new ones prefixed by >>):

>> drivers/xen/unpopulated-alloc.c:42:8: error: implicit declaration of function 'memory_add_physaddr_to_nid' [-Werror,-Wimplicit-function-declaration]
           nid = memory_add_physaddr_to_nid(pgmap->res.start);
                 ^
   1 error generated.

# https://github.com/0day-ci/linux/commit/b66f7f6a65710bd99d21d22f52fa5bc46636d425
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Roger-Pau-Monne/xen-balloon-fixes-for-memory-hotplug/20200901-163414
git checkout b66f7f6a65710bd99d21d22f52fa5bc46636d425
vim +/memory_add_physaddr_to_nid +42 drivers/xen/unpopulated-alloc.c

    17	
    18	static int fill_list(unsigned int nr_pages)
    19	{
    20		struct dev_pagemap *pgmap;
    21		void *vaddr;
    22		unsigned int i, alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
    23		int nid, ret;
    24	
    25		pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
    26		if (!pgmap)
    27			return -ENOMEM;
    28	
    29		pgmap->type = MEMORY_DEVICE_GENERIC;
    30		pgmap->res.name = "Xen scratch";
    31		pgmap->res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
    32	
    33		ret = allocate_resource(&iomem_resource, &pgmap->res,
    34					alloc_pages * PAGE_SIZE, 0, -1,
    35					PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
    36		if (ret < 0) {
    37			pr_err("Cannot allocate new IOMEM resource\n");
    38			kfree(pgmap);
    39			return ret;
    40		}
    41	
  > 42		nid = memory_add_physaddr_to_nid(pgmap->res.start);
    43	

---
0-DAY CI Kernel Test Service, Intel Corporation
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