Re: [v2] fs/proc/task_mmu: Implement IOCTL for efficient page table scanning

[kernel test robot <lkp@intel.com>]

Hi Michał,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on linus/master v6.5-rc2 next-20230721]
[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/Micha-Miros-aw/fs-proc-task_mmu-Implement-IOCTL-for-efficient-page-table-scanning/20230722-082500
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/ZLshsAj5PbsEAHhP%40qmqm.qmqm.pl
patch subject: [v2] fs/proc/task_mmu: Implement IOCTL for efficient page table scanning
config: x86_64-rhel-8.3 (https://download.01.org/0day-ci/archive/20230722/202307222141.3RAiL0jR-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce: (https://download.01.org/0day-ci/archive/20230722/202307222141.3RAiL0jR-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307222141.3RAiL0jR-lkp@intel.com/

All errors (new ones prefixed by >>):

   fs/proc/task_mmu.c: In function 'pagemap_scan_test_walk':
   fs/proc/task_mmu.c:1921:13: error: implicit declaration of function 'userfaultfd_wp_async'; did you mean 'userfaultfd_wp'? [-Werror=implicit-function-declaration]
    1921 |         if (userfaultfd_wp_async(vma) && userfaultfd_wp_use_markers(vma))
         |             ^~~~~~~~~~~~~~~~~~~~
         |             userfaultfd_wp
   fs/proc/task_mmu.c: In function 'pagemap_scan_thp_entry':
>> fs/proc/task_mmu.c:2047:20: error: 'addr' undeclared (first use in this function)
    2047 |         if (end != addr + HPAGE_SIZE) {
         |                    ^~~~
   fs/proc/task_mmu.c:2047:20: note: each undeclared identifier is reported only once for each function it appears in
   cc1: some warnings being treated as errors


vim +/addr +2047 fs/proc/task_mmu.c

  2017	
  2018	static int pagemap_scan_thp_entry(pmd_t *pmd, unsigned long start,
  2019					  unsigned long end, struct mm_walk *walk)
  2020	{
  2021	#ifdef CONFIG_TRANSPARENT_HUGEPAGE
  2022		struct pagemap_scan_private *p = walk->private;
  2023		struct vm_area_struct *vma = walk->vma;
  2024		unsigned long categories;
  2025		spinlock_t *ptl;
  2026		int ret = 0;
  2027	
  2028		ptl = pmd_trans_huge_lock(pmd, vma);
  2029		if (!ptl)
  2030			return -ENOENT;
  2031	
  2032		categories = p->cur_vma_category | pagemap_thp_category(*pmd);
  2033	
  2034		ret = pagemap_scan_output(categories, p, start, &end);
  2035		if (start == end)
  2036			goto out_unlock;
  2037	
  2038		if (~p->arg.flags & PM_SCAN_WP_MATCHING)
  2039			goto out_unlock;
  2040		if (~categories & PAGE_IS_WRITTEN)
  2041			goto out_unlock;
  2042	
  2043		/*
  2044		 * Break huge page into small pages if the WP operation
  2045		 * need to be performed is on a portion of the huge page.
  2046		 */
> 2047		if (end != addr + HPAGE_SIZE) {
  2048			spin_unlock(ptl);
  2049			split_huge_pmd(vma, pmd, start);
  2050			pagemap_scan_backout_range(p, start, end);
  2051			return -ENOENT;
  2052		}
  2053	
  2054		make_uffd_wp_pmd(vma, start, pmd);
  2055		flush_tlb_range(vma, start, end);
  2056	out_unlock:
  2057		spin_unlock(ptl);
  2058		return ret;
  2059	#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
  2060		return -ENOENT;
  2061	#endif
  2062	}
  2063	

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