[PATCH V6 2/4] LoongArch: Add sparse memory vmemmap support

[kernel test robot]

Hi Huacai,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on soc/for-next]
[also build test WARNING on kvm/queue arm64/for-next/core linus/master v5.19]
[cannot apply to akpm-mm/mm-everything tip/x86/mm]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Huacai-Chen/mm-sparse-vmemmap-Generalise-helpers-and-enable-for-LoongArch/20220728-194351
base:   https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
config: loongarch-randconfig-p002-20220801 (https://download.01.org/0day-ci/archive/20220802/202208021409.KLLd0NYP-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 12.1.0
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/d391b94d4c12d54baaf038273712f8da86d50e8d
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Huacai-Chen/mm-sparse-vmemmap-Generalise-helpers-and-enable-for-LoongArch/20220728-194351
        git checkout d391b94d4c12d54baaf038273712f8da86d50e8d
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=loongarch SHELL=/bin/bash arch/loongarch/mm/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp at intel.com>

All warnings (new ones prefixed by >>):

   arch/loongarch/mm/init.c:161:15: warning: no previous prototype for 'vmemmap_populate_hugepages' [-Wmissing-prototypes]
     161 | int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end,
         |               ^~~~~~~~~~~~~~~~~~~~~~~~~~
>> arch/loongarch/mm/init.c:223:6: warning: no previous prototype for 'vmemmap_free' [-Wmissing-prototypes]
     223 | void vmemmap_free(unsigned long start, unsigned long end,
         |      ^~~~~~~~~~~~


vim +/vmemmap_free +223 arch/loongarch/mm/init.c

   159	
   160	#ifdef CONFIG_SPARSEMEM_VMEMMAP
 > 161	int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end,
   162						 int node, struct vmem_altmap *altmap)
   163	{
   164		unsigned long addr = start;
   165		unsigned long next;
   166		pgd_t *pgd;
   167		p4d_t *p4d;
   168		pud_t *pud;
   169		pmd_t *pmd;
   170	
   171		for (addr = start; addr < end; addr = next) {
   172			next = pmd_addr_end(addr, end);
   173	
   174			pgd = vmemmap_pgd_populate(addr, node);
   175			if (!pgd)
   176				return -ENOMEM;
   177			p4d = vmemmap_p4d_populate(pgd, addr, node);
   178			if (!p4d)
   179				return -ENOMEM;
   180			pud = vmemmap_pud_populate(p4d, addr, node);
   181			if (!pud)
   182				return -ENOMEM;
   183	
   184			pmd = pmd_offset(pud, addr);
   185			if (pmd_none(*pmd)) {
   186				void *p = NULL;
   187	
   188				p = vmemmap_alloc_block_buf(PMD_SIZE, node, NULL);
   189				if (p) {
   190					pmd_t entry;
   191	
   192					entry = pfn_pmd(virt_to_pfn(p), PAGE_KERNEL);
   193					pmd_val(entry) |= _PAGE_HUGE | _PAGE_HGLOBAL;
   194					set_pmd_at(&init_mm, addr, pmd, entry);
   195	
   196					continue;
   197				}
   198			} else if (pmd_val(*pmd) & _PAGE_HUGE) {
   199				vmemmap_verify((pte_t *)pmd, node, addr, next);
   200				continue;
   201			}
   202			if (vmemmap_populate_basepages(addr, next, node, NULL))
   203				return -ENOMEM;
   204		}
   205	
   206		return 0;
   207	}
   208	
   209	#if CONFIG_PGTABLE_LEVELS == 2
   210	int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
   211			struct vmem_altmap *altmap)
   212	{
   213		return vmemmap_populate_basepages(start, end, node, NULL);
   214	}
   215	#else
   216	int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
   217			struct vmem_altmap *altmap)
   218	{
   219		return vmemmap_populate_hugepages(start, end, node, NULL);
   220	}
   221	#endif
   222	
 > 223	void vmemmap_free(unsigned long start, unsigned long end,
   224			struct vmem_altmap *altmap)
   225	{
   226	}
   227	#endif
   228	

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