Re: [PATCH] xen/balloon: fix page onlining when populating new zone

[kernel test robot <lkp@intel.com>]

Hi Juergen,

I love your patch! Yet something to improve:

[auto build test ERROR on xen-tip/linux-next]
[also build test ERROR on linus/master linux/master v5.18-rc1 next-20220406]
[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/intel-lab-lkp/linux/commits/Juergen-Gross/xen-balloon-fix-page-onlining-when-populating-new-zone/20220407-000935
base:   https://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git linux-next
config: arm64-randconfig-r011-20220406 (https://download.01.org/0day-ci/archive/20220407/202204071359.uas4tsu0-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 11.2.0
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
        # https://github.com/intel-lab-lkp/linux/commit/b3deb59d5386ade4fb227038f202a9bdb8ade4ab
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Juergen-Gross/xen-balloon-fix-page-onlining-when-populating-new-zone/20220407-000935
        git checkout b3deb59d5386ade4fb227038f202a9bdb8ade4ab
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arm64 SHELL=/bin/bash drivers/

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/balloon.c: In function 'decrease_reservation':
>> drivers/xen/balloon.c:518:24: error: implicit declaration of function 'alloc_page_for_balloon' [-Werror=implicit-function-declaration]
     518 |                 page = alloc_page_for_balloon(gfp);
         |                        ^~~~~~~~~~~~~~~~~~~~~~
   drivers/xen/balloon.c:518:22: warning: assignment to 'struct page *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
     518 |                 page = alloc_page_for_balloon(gfp);
         |                      ^
>> drivers/xen/balloon.c:545:17: error: implicit declaration of function 'add_page_to_balloon' [-Werror=implicit-function-declaration]
     545 |                 add_page_to_balloon(page);
         |                 ^~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/alloc_page_for_balloon +518 drivers/xen/balloon.c

   505	
   506	static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
   507	{
   508		enum bp_state state = BP_DONE;
   509		unsigned long i;
   510		struct page *page, *tmp;
   511		int ret;
   512		LIST_HEAD(pages);
   513	
   514		if (nr_pages > ARRAY_SIZE(frame_list))
   515			nr_pages = ARRAY_SIZE(frame_list);
   516	
   517		for (i = 0; i < nr_pages; i++) {
 > 518			page = alloc_page_for_balloon(gfp);
   519			if (page == NULL) {
   520				nr_pages = i;
   521				state = BP_EAGAIN;
   522				break;
   523			}
   524			list_add(&page->lru, &pages);
   525		}
   526	
   527		/*
   528		 * Ensure that ballooned highmem pages don't have kmaps.
   529		 *
   530		 * Do this before changing the p2m as kmap_flush_unused()
   531		 * reads PTEs to obtain pages (and hence needs the original
   532		 * p2m entry).
   533		 */
   534		kmap_flush_unused();
   535	
   536		/*
   537		 * Setup the frame, update direct mapping, invalidate P2M,
   538		 * and add to balloon.
   539		 */
   540		i = 0;
   541		list_for_each_entry_safe(page, tmp, &pages, lru) {
   542			frame_list[i++] = xen_page_to_gfn(page);
   543	
   544			list_del(&page->lru);
 > 545			add_page_to_balloon(page);
   546		}
   547	
   548		flush_tlb_all();
   549	
   550		ret = xenmem_reservation_decrease(nr_pages, frame_list);
   551		BUG_ON(ret != nr_pages);
   552	
   553		balloon_stats.current_pages -= nr_pages;
   554	
   555		return state;
   556	}
   557	

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