Hi Lukas,

[auto build test WARNING on linus/master]
[also build test WARNING on v4.12 next-20170713]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Lukas-Czerner/fs-Fix-page-cache-inconsistency-when-mixing-buffered-and-AIO-DIO/20170714-181130
config: x86_64-randconfig-x010-201728 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   fs/iomap.c: In function 'iomap_dio_complete':
>> fs/iomap.c:629:25: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
        (offset + dio->size + ret - 1) >> PAGE_SHIFT);
         ~~~~~~~~~~~~~~~~~~~^~~~~

vim +/ret +629 fs/iomap.c

   618	
   619	static ssize_t iomap_dio_complete(struct iomap_dio *dio)
   620	{
   621		struct kiocb *iocb = dio->iocb;
   622		loff_t offset = iocb->ki_pos;
   623		struct inode *inode = file_inode(iocb->ki_filp);
   624		ssize_t ret;
   625	
   626		if ((dio->flags & IOMAP_DIO_WRITE) && inode->i_mapping->nrpages)
   627			invalidate_inode_pages2_range(inode->i_mapping,
   628					offset >> PAGE_SHIFT,
 > 629					(offset + dio->size + ret - 1) >> PAGE_SHIFT);
   630	
   631		if (dio->end_io) {
   632			ret = dio->end_io(iocb,
   633					dio->error ? dio->error : dio->size,
   634					dio->flags);
   635		} else {
   636			ret = dio->error;
   637		}
   638	
   639		if (likely(!ret)) {
   640			ret = dio->size;
   641			/* check for short read */
   642			if (iocb->ki_pos + ret > dio->i_size &&
   643			    !(dio->flags & IOMAP_DIO_WRITE))
   644				ret = dio->i_size - iocb->ki_pos;
   645			iocb->ki_pos += ret;
   646		}
   647	
   648		inode_dio_end(file_inode(iocb->ki_filp));
   649		kfree(dio);
   650	
   651		return ret;
   652	}
   653	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation