Re: [ammarfaizi2-block:akpm/mm/mm-unstable 71/161] mm/ksm.c:2605:7: error: implicit declaration of function 'copy_mc_user_highpage' is invalid in C99

[Kefeng Wang <wangkefeng.wang@huawei.com>]

Hi,  the patch "[PATCH -next v2] mm: hwposion: support recovery from 
ksm_might_need_to_copy()" is

based on next-20221208,  relay on Tony Luck's Patch series 
"Copy-on-write poison recovery".

On 2022/12/10 16:19, kernel test robot wrote:
> tree:   https://github.com/ammarfaizi2/linux-block akpm/mm/mm-unstable
> head:   4661cf99c1e4946297434595994227e47f33c014
> commit: b7edf4b1cdb10106ea63ff2a416b5680d8392dcb [71/161] mm: hwpoison: support recovery from ksm_might_need_to_copy()
> config: i386-randconfig-a002
> compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
> 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
>          # https://github.com/ammarfaizi2/linux-block/commit/b7edf4b1cdb10106ea63ff2a416b5680d8392dcb
>          git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
>          git fetch --no-tags ammarfaizi2-block akpm/mm/mm-unstable
>          git checkout b7edf4b1cdb10106ea63ff2a416b5680d8392dcb
>          # 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=i386 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
>
> Note: the ammarfaizi2-block/akpm/mm/mm-unstable HEAD 4661cf99c1e4946297434595994227e47f33c014 builds fine.
>        It only hurts bisectability.
>
> All errors (new ones prefixed by >>):
>
>>> mm/ksm.c:2605:7: error: implicit declaration of function 'copy_mc_user_highpage' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
>                     if (copy_mc_user_highpage(new_page, page, address, vma)) {
>                         ^
>     mm/ksm.c:2605:7: note: did you mean 'copy_user_highpage'?
>     include/linux/highmem.h:307:20: note: 'copy_user_highpage' declared here
>     static inline void copy_user_highpage(struct page *to, struct page *from,
>                        ^
>     1 error generated.
>
>
> vim +/copy_mc_user_highpage +2605 mm/ksm.c
>
>    2577	
>    2578	struct page *ksm_might_need_to_copy(struct page *page,
>    2579				struct vm_area_struct *vma, unsigned long address)
>    2580	{
>    2581		struct folio *folio = page_folio(page);
>    2582		struct anon_vma *anon_vma = folio_anon_vma(folio);
>    2583		struct page *new_page;
>    2584	
>    2585		if (PageKsm(page)) {
>    2586			if (page_stable_node(page) &&
>    2587			    !(ksm_run & KSM_RUN_UNMERGE))
>    2588				return page;	/* no need to copy it */
>    2589		} else if (!anon_vma) {
>    2590			return page;		/* no need to copy it */
>    2591		} else if (page->index == linear_page_index(vma, address) &&
>    2592				anon_vma->root == vma->anon_vma->root) {
>    2593			return page;		/* still no need to copy it */
>    2594		}
>    2595		if (!PageUptodate(page))
>    2596			return page;		/* let do_swap_page report the error */
>    2597	
>    2598		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
>    2599		if (new_page &&
>    2600		    mem_cgroup_charge(page_folio(new_page), vma->vm_mm, GFP_KERNEL)) {
>    2601			put_page(new_page);
>    2602			new_page = NULL;
>    2603		}
>    2604		if (new_page) {
>> 2605			if (copy_mc_user_highpage(new_page, page, address, vma)) {
>    2606				put_page(new_page);
>    2607				new_page = ERR_PTR(-EHWPOISON);
>    2608				memory_failure_queue(page_to_pfn(page), 0);
>    2609				return new_page;
>    2610			}
>    2611			SetPageDirty(new_page);
>    2612			__SetPageUptodate(new_page);
>    2613			__SetPageLocked(new_page);
>    2614	#ifdef CONFIG_SWAP
>    2615			count_vm_event(KSM_SWPIN_COPY);
>    2616	#endif
>    2617		}
>    2618	
>    2619		return new_page;
>    2620	}
>    2621	
>