Hi David,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git work.mount
head:   972cb8216dab124b3cb580a5a1d2989337827ff2
commit: a939e8d3e17037ae1f4ea6c0349418221e1d82ef [40/43] vfs: Implement logging through fs_context
config: ia64-allnoconfig (attached as .config)
compiler: ia64-linux-gcc (GCC) 8.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout a939e8d3e17037ae1f4ea6c0349418221e1d82ef
        # save the attached .config to linux build tree
        GCC_VERSION=8.2.0 make.cross ARCH=ia64 

All errors (new ones prefixed by >>):

   fs/fs_context.c: In function 'logfc':
>> fs/fs_context.c:394:3: error: implicit declaration of function 'vprintk_emit'; did you mean 'dev_printk_emit'? [-Werror=implicit-function-declaration]
      vprintk_emit(0, LOGLEVEL_WARNING, NULL, 0, fmt, va);
      ^~~~~~~~~~~~
      dev_printk_emit
   cc1: some warnings being treated as errors

vim +394 fs/fs_context.c

   380	
   381	/**
   382	 * logfc - Log a message to a filesystem context
   383	 * @fc: The filesystem context to log to.
   384	 * @fmt: The format of the buffer.
   385	 */
   386	void logfc(struct fs_context *fc, const char *fmt, ...)
   387	{
   388		va_list va;
   389	
   390		va_start(va, fmt);
   391	
   392		switch (fmt[0]) {
   393		case 'w':
 > 394			vprintk_emit(0, LOGLEVEL_WARNING, NULL, 0, fmt, va);
   395			break;
   396		case 'e':
   397			vprintk_emit(0, LOGLEVEL_ERR, NULL, 0, fmt, va);
   398			break;
   399		default:
   400			vprintk_emit(0, LOGLEVEL_NOTICE, NULL, 0, fmt, va);
   401			break;
   402		}
   403	
   404		pr_cont("\n");
   405		va_end(va);
   406	}
   407	EXPORT_SYMBOL(logfc);
   408	

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