Re: [PATCH v2 5/7] mm:swap: use on-stack-bio for BDI_CAP_SYNCHRONOUS device

[Minchan Kim]

On Sat, Aug 12, 2017 at 04:46:33PM +0800, kbuild test robot wrote:
> Hi Minchan,
> 
> [auto build test ERROR on mmotm/master]
> [also build test ERROR on next-20170811]
> [cannot apply to linus/master v4.13-rc4]
> [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/Minchan-Kim/Replace-rw_page-with-on-stack-bio/20170812-152541
> base:   git://git.cmpxchg.org/linux-mmotm.git master
> config: sparc64-allmodconfig (attached as .config)
> compiler: sparc64-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
> reproduce:
>         wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # save the attached .config to linux build tree
>         make.cross ARCH=sparc64 
> 
> All errors (new ones prefixed by >>):
> 
>    mm/page_io.c: In function '__swap_writepage':
> >> mm/page_io.c:345:11: error: passing argument 1 of 'bio_get' from incompatible pointer type [-Werror=incompatible-pointer-types]
>       bio_get(&bio);
>               ^
>    In file included from include/linux/writeback.h:205:0,
>                     from include/linux/memcontrol.h:31,
>                     from include/linux/swap.h:8,
>                     from mm/page_io.c:17:
>    include/linux/bio.h:252:20: note: expected 'struct bio *' but argument is of type 'struct bio **'
>     static inline void bio_get(struct bio *bio)
>                        ^~~~~~~
>    cc1: some warnings being treated as errors
> 
> vim +/bio_get +345 mm/page_io.c
> 
>    275	
>    276	int __swap_writepage(struct page *page, struct writeback_control *wbc)
>    277	{
>    278		int ret;
>    279		struct swap_info_struct *sis = page_swap_info(page);
>    280		struct bio *bio;
>    281		/* on-stack-bio */
>    282		struct bio sbio;
>    283		struct bio_vec sbvec;
>    284	
>    285		VM_BUG_ON_PAGE(!PageSwapCache(page), page);
>    286		if (sis->flags & SWP_FILE) {
>    287			struct kiocb kiocb;
>    288			struct file *swap_file = sis->swap_file;
>    289			struct address_space *mapping = swap_file->f_mapping;
>    290			struct bio_vec bv = {
>    291				.bv_page = page,
>    292				.bv_len  = PAGE_SIZE,
>    293				.bv_offset = 0
>    294			};
>    295			struct iov_iter from;
>    296	
>    297			iov_iter_bvec(&from, ITER_BVEC | WRITE, &bv, 1, PAGE_SIZE);
>    298			init_sync_kiocb(&kiocb, swap_file);
>    299			kiocb.ki_pos = page_file_offset(page);
>    300	
>    301			set_page_writeback(page);
>    302			unlock_page(page);
>    303			ret = mapping->a_ops->direct_IO(&kiocb, &from);
>    304			if (ret == PAGE_SIZE) {
>    305				count_vm_event(PSWPOUT);
>    306				ret = 0;
>    307			} else {
>    308				/*
>    309				 * In the case of swap-over-nfs, this can be a
>    310				 * temporary failure if the system has limited
>    311				 * memory for allocating transmit buffers.
>    312				 * Mark the page dirty and avoid
>    313				 * rotate_reclaimable_page but rate-limit the
>    314				 * messages but do not flag PageError like
>    315				 * the normal direct-to-bio case as it could
>    316				 * be temporary.
>    317				 */
>    318				set_page_dirty(page);
>    319				ClearPageReclaim(page);
>    320				pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
>    321						   page_file_offset(page));
>    322			}
>    323			end_page_writeback(page);
>    324			return ret;
>    325		}
>    326	
>    327		ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
>    328		if (!ret) {
>    329			count_swpout_vm_event(page);
>    330			return 0;
>    331		}
>    332	
>    333		ret = 0;
>    334		if (!(sis->flags & SWP_SYNC_IO)) {
>    335	
>    336			bio = get_swap_bio(GFP_NOIO, page, end_swap_bio_write);
>    337			if (bio == NULL) {
>    338				set_page_dirty(page);
>    339				unlock_page(page);
>    340				ret = -ENOMEM;
>    341				goto out;
>    342			}
>    343		} else {
>    344			bio = &sbio;
>  > 345			bio_get(&bio);

Hi kbuild,

I will respin with fixing it.
Thanks for the catching up!