Re: [PATCH 03/13] kernfs: add support for get_unmapped_area callback

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

Hi Hou,

kernel test robot noticed the following build errors:

[auto build test ERROR on driver-core/driver-core-testing]
[also build test ERROR on driver-core/driver-core-next driver-core/driver-core-linus akpm-mm/mm-everything linus/master v6.19-rc1 next-20251219]
[cannot apply to pci/next pci/for-linus]
[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/Hou-Tao/PCI-P2PDMA-Release-the-per-cpu-ref-of-pgmap-when-vm_insert_page-fails/20251220-121804
base:   driver-core/driver-core-testing
patch link:    https://lore.kernel.org/r/20251220040446.274991-4-houtao%40huaweicloud.com
patch subject: [PATCH 03/13] kernfs: add support for get_unmapped_area callback
config: arm-allnoconfig (https://download.01.org/0day-ci/archive/20251220/202512202338.qFqw6FI8-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project b324c9f4fa112d61a553bf489b5f4f7ceea05ea8)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251220/202512202338.qFqw6FI8-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512202338.qFqw6FI8-lkp@intel.com/

All errors (new ones prefixed by >>):

>> fs/kernfs/file.c:480:9: error: call to undeclared function 'mm_get_unmapped_area'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     480 |         addr = mm_get_unmapped_area(file, uaddr, len, pgoff, flags);
         |                ^
   fs/kernfs/file.c:480:9: note: did you mean '__get_unmapped_area'?
   include/linux/mm.h:3671:1: note: '__get_unmapped_area' declared here
    3671 | __get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
         | ^
   1 error generated.


vim +/mm_get_unmapped_area +480 fs/kernfs/file.c

   456	
   457	static unsigned long kernfs_get_unmapped_area(struct file *file, unsigned long uaddr,
   458						      unsigned long len, unsigned long pgoff,
   459						      unsigned long flags)
   460	{
   461		struct kernfs_open_file *of = kernfs_of(file);
   462		const struct kernfs_ops *ops;
   463		long addr;
   464	
   465		if (!(of->kn->flags & KERNFS_HAS_MMAP))
   466			return -ENODEV;
   467	
   468		mutex_lock(&of->mutex);
   469	
   470		addr = -ENODEV;
   471		if (!kernfs_get_active_of(of))
   472			goto out_unlock;
   473	
   474		ops = kernfs_ops(of->kn);
   475		if (ops->get_unmapped_area) {
   476			addr = ops->get_unmapped_area(of, uaddr, len, pgoff, flags);
   477			if (!IS_ERR_VALUE(addr) || addr != -EOPNOTSUPP)
   478				goto out_put;
   479		}
 > 480		addr = mm_get_unmapped_area(file, uaddr, len, pgoff, flags);
   481	
   482	out_put:
   483		kernfs_put_active_of(of);
   484	out_unlock:
   485		mutex_unlock(&of->mutex);
   486	
   487		return addr;
   488	}
   489	

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