Re: [PATCH 7/7] mm: return an ERR_PTR from __filemap_get_folio

Re: [PATCH 7/7] mm: return an ERR_PTR from __filemap_get_folio

[kernel test robot]

Hi Christoph,

I love your patch! Perhaps something to improve:

[auto build test WARNING on next-20230120]
[cannot apply to akpm-mm/mm-everything tytso-ext4/dev kdave/for-next xfs-linux/for-next konis-nilfs2/upstream linus/master v6.2-rc4 v6.2-rc3 v6.2-rc2 v6.2-rc4]
[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/Christoph-Hellwig/mm-make-mapping_get_entry-available-outside-of-filemap-c/20230121-155847
patch link:    https://lore.kernel.org/r/20230121065755.1140136-8-hch%40lst.de
patch subject: [PATCH 7/7] mm: return an ERR_PTR from __filemap_get_folio
config: riscv-randconfig-r013-20230119 (https://download.01.org/0day-ci/archive/20230121/202301211944.5T9l1RgA-lkp@intel.com/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 4196ca3278f78c6e19246e54ab0ecb364e37d66a)
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
        # install riscv cross compiling tool for clang build
        # apt-get install binutils-riscv-linux-gnu
        # https://github.com/intel-lab-lkp/linux/commit/3c8a98fd03b82ace84668b3f8bb48d48e9f34af2
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Christoph-Hellwig/mm-make-mapping_get_entry-available-outside-of-filemap-c/20230121-155847
        git checkout 3c8a98fd03b82ace84668b3f8bb48d48e9f34af2
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash fs/iomap/

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

All warnings (new ones prefixed by >>):

>> fs/iomap/buffered-io.c:669:28: warning: variable 'folio' is uninitialized when used here [-Wuninitialized]
           if (pos + len > folio_pos(folio) + folio_size(folio))
                                     ^~~~~
   fs/iomap/buffered-io.c:636:21: note: initialize the variable 'folio' to silence this warning
           struct folio *folio;
                              ^
                               = NULL
   fs/iomap/buffered-io.c:598:22: warning: unused function '__iomap_get_folio' [-Wunused-function]
   static struct folio *__iomap_get_folio(struct iomap_iter *iter, loff_t pos,
                        ^
   2 warnings generated.


vim +/folio +669 fs/iomap/buffered-io.c

69f4a26c1e0c7c Gao Xiang               2021-08-03  630  
d7b64041164ca1 Dave Chinner            2022-11-29  631  static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
bc6123a84a71b5 Matthew Wilcox (Oracle  2021-05-02  632) 		size_t len, struct folio **foliop)
afc51aaa22f26c Darrick J. Wong         2019-07-15  633  {
471859f57d4253 Andreas Gruenbacher     2023-01-15  634  	const struct iomap_folio_ops *folio_ops = iter->iomap.folio_ops;
fad0a1ab34f777 Christoph Hellwig       2021-08-10  635  	const struct iomap *srcmap = iomap_iter_srcmap(iter);
d1bd0b4ebfe052 Matthew Wilcox (Oracle  2021-11-03  636) 	struct folio *folio;
afc51aaa22f26c Darrick J. Wong         2019-07-15  637  	int status = 0;
afc51aaa22f26c Darrick J. Wong         2019-07-15  638  
1b5c1e36dc0e0f Christoph Hellwig       2021-08-10  639  	BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length);
1b5c1e36dc0e0f Christoph Hellwig       2021-08-10  640  	if (srcmap != &iter->iomap)
c039b997927263 Goldwyn Rodrigues       2019-10-18  641  		BUG_ON(pos + len > srcmap->offset + srcmap->length);
afc51aaa22f26c Darrick J. Wong         2019-07-15  642  
afc51aaa22f26c Darrick J. Wong         2019-07-15  643  	if (fatal_signal_pending(current))
afc51aaa22f26c Darrick J. Wong         2019-07-15  644  		return -EINTR;
afc51aaa22f26c Darrick J. Wong         2019-07-15  645  
d454ab82bc7f4a Matthew Wilcox (Oracle  2021-12-09  646) 	if (!mapping_large_folio_support(iter->inode->i_mapping))
d454ab82bc7f4a Matthew Wilcox (Oracle  2021-12-09  647) 		len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
d454ab82bc7f4a Matthew Wilcox (Oracle  2021-12-09  648) 
d7b64041164ca1 Dave Chinner            2022-11-29  649  	/*
d7b64041164ca1 Dave Chinner            2022-11-29  650  	 * Now we have a locked folio, before we do anything with it we need to
d7b64041164ca1 Dave Chinner            2022-11-29  651  	 * check that the iomap we have cached is not stale. The inode extent
d7b64041164ca1 Dave Chinner            2022-11-29  652  	 * mapping can change due to concurrent IO in flight (e.g.
d7b64041164ca1 Dave Chinner            2022-11-29  653  	 * IOMAP_UNWRITTEN state can change and memory reclaim could have
d7b64041164ca1 Dave Chinner            2022-11-29  654  	 * reclaimed a previously partially written page at this index after IO
d7b64041164ca1 Dave Chinner            2022-11-29  655  	 * completion before this write reaches this file offset) and hence we
d7b64041164ca1 Dave Chinner            2022-11-29  656  	 * could do the wrong thing here (zero a page range incorrectly or fail
d7b64041164ca1 Dave Chinner            2022-11-29  657  	 * to zero) and corrupt data.
d7b64041164ca1 Dave Chinner            2022-11-29  658  	 */
471859f57d4253 Andreas Gruenbacher     2023-01-15  659  	if (folio_ops && folio_ops->iomap_valid) {
471859f57d4253 Andreas Gruenbacher     2023-01-15  660  		bool iomap_valid = folio_ops->iomap_valid(iter->inode,
d7b64041164ca1 Dave Chinner            2022-11-29  661  							 &iter->iomap);
d7b64041164ca1 Dave Chinner            2022-11-29  662  		if (!iomap_valid) {
d7b64041164ca1 Dave Chinner            2022-11-29  663  			iter->iomap.flags |= IOMAP_F_STALE;
d7b64041164ca1 Dave Chinner            2022-11-29  664  			status = 0;
d7b64041164ca1 Dave Chinner            2022-11-29  665  			goto out_unlock;
d7b64041164ca1 Dave Chinner            2022-11-29  666  		}
d7b64041164ca1 Dave Chinner            2022-11-29  667  	}
d7b64041164ca1 Dave Chinner            2022-11-29  668  
d454ab82bc7f4a Matthew Wilcox (Oracle  2021-12-09 @669) 	if (pos + len > folio_pos(folio) + folio_size(folio))
d454ab82bc7f4a Matthew Wilcox (Oracle  2021-12-09  670) 		len = folio_pos(folio) + folio_size(folio) - pos;
afc51aaa22f26c Darrick J. Wong         2019-07-15  671  
c039b997927263 Goldwyn Rodrigues       2019-10-18  672  	if (srcmap->type == IOMAP_INLINE)
bc6123a84a71b5 Matthew Wilcox (Oracle  2021-05-02  673) 		status = iomap_write_begin_inline(iter, folio);
1b5c1e36dc0e0f Christoph Hellwig       2021-08-10  674  	else if (srcmap->flags & IOMAP_F_BUFFER_HEAD)
d1bd0b4ebfe052 Matthew Wilcox (Oracle  2021-11-03  675) 		status = __block_write_begin_int(folio, pos, len, NULL, srcmap);
afc51aaa22f26c Darrick J. Wong         2019-07-15  676  	else
bc6123a84a71b5 Matthew Wilcox (Oracle  2021-05-02  677) 		status = __iomap_write_begin(iter, pos, len, folio);
afc51aaa22f26c Darrick J. Wong         2019-07-15  678  
afc51aaa22f26c Darrick J. Wong         2019-07-15  679  	if (unlikely(status))
afc51aaa22f26c Darrick J. Wong         2019-07-15  680  		goto out_unlock;
afc51aaa22f26c Darrick J. Wong         2019-07-15  681  
bc6123a84a71b5 Matthew Wilcox (Oracle  2021-05-02  682) 	*foliop = folio;
afc51aaa22f26c Darrick J. Wong         2019-07-15  683  	return 0;
afc51aaa22f26c Darrick J. Wong         2019-07-15  684  
afc51aaa22f26c Darrick J. Wong         2019-07-15  685  out_unlock:
7a70a5085ed028 Andreas Gruenbacher     2023-01-15  686  	__iomap_put_folio(iter, pos, 0, folio);
1b5c1e36dc0e0f Christoph Hellwig       2021-08-10  687  	iomap_write_failed(iter->inode, pos, len);
afc51aaa22f26c Darrick J. Wong         2019-07-15  688  
afc51aaa22f26c Darrick J. Wong         2019-07-15  689  	return status;
afc51aaa22f26c Darrick J. Wong         2019-07-15  690  }
afc51aaa22f26c Darrick J. Wong         2019-07-15  691  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

Re: [PATCH 7/7] mm: return an ERR_PTR from __filemap_get_folio

[Christoph Hellwig]

On Sat, Jan 21, 2023 at 07:52:54PM +0800, kernel test robot wrote:
> Hi Christoph,
> 
> I love your patch! Perhaps something to improve:

And I don't love all this hugging when something doesn't work.  It feels
passive aggressive.

That being said, in this case the error is becaue the series is against
linux-next, so applying it to mainline won't work.