[linux-next:master 7701/8232] mm/huge_memory.c:2735 __discard_anon_folio_pmd_locked() error: uninitialized symbol 'page'.

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

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: Linux Memory Management List <linux-mm@kvack.org>
TO: Lance Yang <ioworker0@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Linux Memory Management List <linux-mm@kvack.org>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   0fc4bfab2cd45f9acb86c4f04b5191e114e901ed
commit: 4627108658d68fad359600dbe667b88b501cee71 [7701/8232] mm/vmscan: avoid split lazyfree THP during shrink_folio_list()
:::::: branch date: 25 hours ago
:::::: commit date: 2 days ago
config: i386-randconfig-141-20240626 (https://download.01.org/0day-ci/archive/20240627/202406270108.7yneS068-lkp@intel.com/config)
compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0

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>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202406270108.7yneS068-lkp@intel.com/

smatch warnings:
mm/huge_memory.c:2735 __discard_anon_folio_pmd_locked() error: uninitialized symbol 'page'.

vim +/page +2735 mm/huge_memory.c

e9b61f19858a5d Kirill A. Shutemov 2016-01-15  2691  
4627108658d68f Lance Yang         2024-06-14  2692  static bool __discard_anon_folio_pmd_locked(struct vm_area_struct *vma,
4627108658d68f Lance Yang         2024-06-14  2693  					    unsigned long addr, pmd_t *pmdp,
4627108658d68f Lance Yang         2024-06-14  2694  					    struct folio *folio)
4627108658d68f Lance Yang         2024-06-14  2695  {
4627108658d68f Lance Yang         2024-06-14  2696  	struct mm_struct *mm = vma->vm_mm;
4627108658d68f Lance Yang         2024-06-14  2697  	int ref_count, map_count;
4627108658d68f Lance Yang         2024-06-14  2698  	pmd_t orig_pmd = *pmdp;
4627108658d68f Lance Yang         2024-06-14  2699  	struct page *page;
4627108658d68f Lance Yang         2024-06-14  2700  
4627108658d68f Lance Yang         2024-06-14  2701  	if (folio_test_dirty(folio) || pmd_dirty(orig_pmd))
4627108658d68f Lance Yang         2024-06-14  2702  		return false;
4627108658d68f Lance Yang         2024-06-14  2703  
4627108658d68f Lance Yang         2024-06-14  2704  	orig_pmd = pmdp_huge_clear_flush(vma, addr, pmdp);
4627108658d68f Lance Yang         2024-06-14  2705  
4627108658d68f Lance Yang         2024-06-14  2706  	/*
4627108658d68f Lance Yang         2024-06-14  2707  	 * Syncing against concurrent GUP-fast:
4627108658d68f Lance Yang         2024-06-14  2708  	 * - clear PMD; barrier; read refcount
4627108658d68f Lance Yang         2024-06-14  2709  	 * - inc refcount; barrier; read PMD
4627108658d68f Lance Yang         2024-06-14  2710  	 */
4627108658d68f Lance Yang         2024-06-14  2711  	smp_mb();
4627108658d68f Lance Yang         2024-06-14  2712  
4627108658d68f Lance Yang         2024-06-14  2713  	ref_count = folio_ref_count(folio);
4627108658d68f Lance Yang         2024-06-14  2714  	map_count = folio_mapcount(folio);
4627108658d68f Lance Yang         2024-06-14  2715  
4627108658d68f Lance Yang         2024-06-14  2716  	/*
4627108658d68f Lance Yang         2024-06-14  2717  	 * Order reads for folio refcount and dirty flag
4627108658d68f Lance Yang         2024-06-14  2718  	 * (see comments in __remove_mapping()).
4627108658d68f Lance Yang         2024-06-14  2719  	 */
4627108658d68f Lance Yang         2024-06-14  2720  	smp_rmb();
4627108658d68f Lance Yang         2024-06-14  2721  
4627108658d68f Lance Yang         2024-06-14  2722  	/*
4627108658d68f Lance Yang         2024-06-14  2723  	 * If the folio or its PMD is redirtied at this point, or if there
4627108658d68f Lance Yang         2024-06-14  2724  	 * are unexpected references, we will give up to discard this folio
4627108658d68f Lance Yang         2024-06-14  2725  	 * and remap it.
4627108658d68f Lance Yang         2024-06-14  2726  	 *
4627108658d68f Lance Yang         2024-06-14  2727  	 * The only folio refs must be one from isolation plus the rmap(s).
4627108658d68f Lance Yang         2024-06-14  2728  	 */
4627108658d68f Lance Yang         2024-06-14  2729  	if (folio_test_dirty(folio) || pmd_dirty(orig_pmd) ||
4627108658d68f Lance Yang         2024-06-14  2730  	    ref_count != map_count + 1) {
4627108658d68f Lance Yang         2024-06-14  2731  		set_pmd_at(mm, addr, pmdp, orig_pmd);
4627108658d68f Lance Yang         2024-06-14  2732  		return false;
4627108658d68f Lance Yang         2024-06-14  2733  	}
4627108658d68f Lance Yang         2024-06-14  2734  
4627108658d68f Lance Yang         2024-06-14 @2735  	folio_remove_rmap_pmd(folio, page, vma);
4627108658d68f Lance Yang         2024-06-14  2736  	zap_deposited_table(mm, pmdp);
4627108658d68f Lance Yang         2024-06-14  2737  	add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR);
4627108658d68f Lance Yang         2024-06-14  2738  	if (vma->vm_flags & VM_LOCKED)
4627108658d68f Lance Yang         2024-06-14  2739  		mlock_drain_local();
4627108658d68f Lance Yang         2024-06-14  2740  	folio_put(folio);
4627108658d68f Lance Yang         2024-06-14  2741  
4627108658d68f Lance Yang         2024-06-14  2742  	return true;
4627108658d68f Lance Yang         2024-06-14  2743  }
4627108658d68f Lance Yang         2024-06-14  2744  

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