[ammarfaizi2-block:akpm/mm/mm-unstable 160/254] mm/rmap.c:1325 page_add_anon_rmap() error: uninitialized symbol 'first'.

[Dan Carpenter <error27@gmail.com>]

tree:   https://github.com/ammarfaizi2/linux-block akpm/mm/mm-unstable
head:   a8da2493d983a10242e6c9d71c6e828aafa5baf8
commit: d68dde0dc6f8b8d09357a32473db8881173b10b0 [160/254] mm,thp,rmap: subpages_mapcount of PTE-mapped subpages
config: i386-randconfig-m021
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>

smatch warnings:
mm/rmap.c:1325 page_add_anon_rmap() error: uninitialized symbol 'first'.

vim +/first +1325 mm/rmap.c

9617d95e6e9ffd Nicholas Piggin    2006-01-06  1278  void page_add_anon_rmap(struct page *page,
14f9135d547060 David Hildenbrand  2022-05-09  1279  	struct vm_area_struct *vma, unsigned long address, rmap_t flags)
9617d95e6e9ffd Nicholas Piggin    2006-01-06  1280  {
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1281  	struct compound_mapcounts mapcounts;
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1282  	int nr = 0, nr_pmdmapped = 0;
d281ee61451835 Kirill A. Shutemov 2016-01-15  1283  	bool compound = flags & RMAP_COMPOUND;
53f9263baba69f Kirill A. Shutemov 2016-01-15  1284  	bool first;
                                                        ^^^^^^^^^^
53f9263baba69f Kirill A. Shutemov 2016-01-15  1285  
be5d0a74c62d8d Johannes Weiner    2020-06-03  1286  	if (unlikely(PageKsm(page)))
be5d0a74c62d8d Johannes Weiner    2020-06-03  1287  		lock_page_memcg(page);
be5d0a74c62d8d Johannes Weiner    2020-06-03  1288  
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1289  	if (likely(!compound /* page is mapped by PTE */)) {
84e6cb5a201a85 Hugh Dickins       2022-11-09  1290  		first = atomic_inc_and_test(&page->_mapcount);
84e6cb5a201a85 Hugh Dickins       2022-11-09  1291  		nr = first;
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1292  		if (first && PageCompound(page)) {
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1293  			struct page *head = compound_head(page);
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1294  
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1295  			lock_compound_mapcounts(head, &mapcounts);
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1296  			mapcounts.subpages_mapcount++;
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1297  			nr = !mapcounts.compound_mapcount;
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1298  			unlock_compound_mapcounts(head, &mapcounts);
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1299  		}
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1300  	} else if (PageTransHuge(page)) {
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1301  		/* That test is redundant: it's for safety or to optimize out */
84e6cb5a201a85 Hugh Dickins       2022-11-09  1302  
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1303  		lock_compound_mapcounts(page, &mapcounts);
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1304  		first = !mapcounts.compound_mapcount;
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1305  		mapcounts.compound_mapcount++;
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1306  		if (first) {
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1307  			nr_pmdmapped = thp_nr_pages(page);
d68dde0dc6f8b8 Hugh Dickins       2022-11-18  1308  			nr = nr_pmdmapped - mapcounts.subpages_mapcount;
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1309  		}
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1310  		unlock_compound_mapcounts(page, &mapcounts);
53f9263baba69f Kirill A. Shutemov 2016-01-15  1311  	}

No else path.

bde3d57e6cec9c Hugh Dickins       2022-11-02  1312  
6c287605fd5646 David Hildenbrand  2022-05-09  1313  	VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page);
                                                                        ^^^^^
Uninitialized.


6c287605fd5646 David Hildenbrand  2022-05-09  1314  	VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page);
53f9263baba69f Kirill A. Shutemov 2016-01-15  1315  
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1316  	if (nr_pmdmapped)
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1317  		__mod_lruvec_page_state(page, NR_ANON_THPS, nr_pmdmapped);
5b3276bc4a2e01 Hugh Dickins       2022-11-02  1318  	if (nr)
be5d0a74c62d8d Johannes Weiner    2020-06-03  1319  		__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr);
5ad6468801d28c Hugh Dickins       2009-12-14  1320  
cea86fe246b694 Hugh Dickins       2022-02-14  1321  	if (unlikely(PageKsm(page)))
be5d0a74c62d8d Johannes Weiner    2020-06-03  1322  		unlock_page_memcg(page);
53f9263baba69f Kirill A. Shutemov 2016-01-15  1323  
5dbe0af47f8a8f Hugh Dickins       2011-05-28  1324  	/* address might be in next vma when migration races vma_adjust */
cea86fe246b694 Hugh Dickins       2022-02-14 @1325  	else if (first)
d281ee61451835 Kirill A. Shutemov 2016-01-15  1326  		__page_set_anon_rmap(page, vma, address,
14f9135d547060 David Hildenbrand  2022-05-09  1327  				     !!(flags & RMAP_EXCLUSIVE));
69029cd550284e KAMEZAWA Hiroyuki  2008-07-25  1328  	else
c97a9e10eaee32 Nicholas Piggin    2007-05-16  1329  		__page_check_anon_rmap(page, vma, address);
cea86fe246b694 Hugh Dickins       2022-02-14  1330  
cea86fe246b694 Hugh Dickins       2022-02-14  1331  	mlock_vma_page(page, vma, compound);
^1da177e4c3f41 Linus Torvalds     2005-04-16  1332  }

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