[akpm-mm:mm-unstable 75/80] drivers/video/fbdev/core/fb_defio.c:272:3: error: call to undeclared function 'mapping_wrprotect_page'; ISO C99 and later do not support implicit function declarations

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

Hi Lorenzo,

FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
head:   7de6fd8ab65003f050aa58e705592745717ed318
commit: 6a9318f28d7e371692838677c364145fe04b1093 [75/80] fb_defio: do not use deprecated page->mapping, index fields
config: arm-randconfig-001-20250203 (https://download.01.org/0day-ci/archive/20250203/202502030356.JNL7I49s-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250203/202502030356.JNL7I49s-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/202502030356.JNL7I49s-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/video/fbdev/core/fb_defio.c:272:3: error: call to undeclared function 'mapping_wrprotect_page'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     272 |                 mapping_wrprotect_page(fbdefio->mapping, pgoff, 1, page);
         |                 ^
   1 error generated.


vim +/mapping_wrprotect_page +272 drivers/video/fbdev/core/fb_defio.c

   258	
   259	/* workqueue callback */
   260	static void fb_deferred_io_work(struct work_struct *work)
   261	{
   262		struct fb_info *info = container_of(work, struct fb_info, deferred_work.work);
   263		struct fb_deferred_io_pageref *pageref, *next;
   264		struct fb_deferred_io *fbdefio = info->fbdefio;
   265	
   266		/* here we wrprotect the page's mappings, then do all deferred IO. */
   267		mutex_lock(&fbdefio->lock);
   268		list_for_each_entry(pageref, &fbdefio->pagereflist, list) {
   269			struct page *page = pageref->page;
   270			pgoff_t pgoff = pageref->offset >> PAGE_SHIFT;
   271	
 > 272			mapping_wrprotect_page(fbdefio->mapping, pgoff, 1, page);
   273		}
   274	
   275		/* driver's callback with pagereflist */
   276		fbdefio->deferred_io(info, &fbdefio->pagereflist);
   277	
   278		/* clear the list */
   279		list_for_each_entry_safe(pageref, next, &fbdefio->pagereflist, list)
   280			fb_deferred_io_pageref_put(pageref, info);
   281	
   282		mutex_unlock(&fbdefio->lock);
   283	}
   284	

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