Hi Matthew, kernel test robot noticed the following build warnings: [auto build test WARNING on akpm-mm/mm-everything] url: https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/mm-Add-pfn_swap_entry_folio/20240111-232757 base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything patch link: https://lore.kernel.org/r/20240111152429.3374566-9-willy%40infradead.org patch subject: [PATCH v3 08/10] mm: Convert to should_zap_page() to should_zap_folio() config: arm-milbeaut_m10v_defconfig (https://download.01.org/0day-ci/archive/20240112/202401121250.A221BL2D-lkp@xxxxxxxxx/config) compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240112/202401121250.A221BL2D-lkp@xxxxxxxxx/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@xxxxxxxxx> | Closes: https://lore.kernel.org/oe-kbuild-all/202401121250.A221BL2D-lkp@xxxxxxxxx/ All warnings (new ones prefixed by >>): >> mm/memory.c:1451:8: warning: variable 'folio' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] if (page) ^~~~ mm/memory.c:1454:44: note: uninitialized use occurs here if (unlikely(!should_zap_folio(details, folio))) ^~~~~ include/linux/compiler.h:77:42: note: expanded from macro 'unlikely' # define unlikely(x) __builtin_expect(!!(x), 0) ^ mm/memory.c:1451:4: note: remove the 'if' if its condition is always true if (page) ^~~~~~~~~ mm/memory.c:1438:22: note: initialize the variable 'folio' to silence this warning struct folio *folio; ^ = NULL 1 warning generated. vim +1451 mm/memory.c 1414 1415 static unsigned long zap_pte_range(struct mmu_gather *tlb, 1416 struct vm_area_struct *vma, pmd_t *pmd, 1417 unsigned long addr, unsigned long end, 1418 struct zap_details *details) 1419 { 1420 struct mm_struct *mm = tlb->mm; 1421 int force_flush = 0; 1422 int rss[NR_MM_COUNTERS]; 1423 spinlock_t *ptl; 1424 pte_t *start_pte; 1425 pte_t *pte; 1426 swp_entry_t entry; 1427 1428 tlb_change_page_size(tlb, PAGE_SIZE); 1429 init_rss_vec(rss); 1430 start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 1431 if (!pte) 1432 return addr; 1433 1434 flush_tlb_batched_pending(mm); 1435 arch_enter_lazy_mmu_mode(); 1436 do { 1437 pte_t ptent = ptep_get(pte); 1438 struct folio *folio; 1439 struct page *page; 1440 1441 if (pte_none(ptent)) 1442 continue; 1443 1444 if (need_resched()) 1445 break; 1446 1447 if (pte_present(ptent)) { 1448 unsigned int delay_rmap; 1449 1450 page = vm_normal_page(vma, addr, ptent); > 1451 if (page) 1452 folio = page_folio(page); 1453 1454 if (unlikely(!should_zap_folio(details, folio))) 1455 continue; 1456 ptent = ptep_get_and_clear_full(mm, addr, pte, 1457 tlb->fullmm); 1458 arch_check_zapped_pte(vma, ptent); 1459 tlb_remove_tlb_entry(tlb, pte, addr); 1460 zap_install_uffd_wp_if_needed(vma, addr, pte, details, 1461 ptent); 1462 if (unlikely(!page)) { 1463 ksm_might_unmap_zero_page(mm, ptent); 1464 continue; 1465 } 1466 1467 delay_rmap = 0; 1468 if (!folio_test_anon(folio)) { 1469 if (pte_dirty(ptent)) { 1470 folio_set_dirty(folio); 1471 if (tlb_delay_rmap(tlb)) { 1472 delay_rmap = 1; 1473 force_flush = 1; 1474 } 1475 } 1476 if (pte_young(ptent) && likely(vma_has_recency(vma))) 1477 folio_mark_accessed(folio); 1478 } 1479 rss[mm_counter(page)]--; 1480 if (!delay_rmap) { 1481 folio_remove_rmap_pte(folio, page, vma); 1482 if (unlikely(page_mapcount(page) < 0)) 1483 print_bad_pte(vma, addr, ptent, page); 1484 } 1485 if (unlikely(__tlb_remove_page(tlb, page, delay_rmap))) { 1486 force_flush = 1; 1487 addr += PAGE_SIZE; 1488 break; 1489 } 1490 continue; 1491 } 1492 1493 entry = pte_to_swp_entry(ptent); 1494 if (is_device_private_entry(entry) || 1495 is_device_exclusive_entry(entry)) { 1496 page = pfn_swap_entry_to_page(entry); 1497 folio = page_folio(page); 1498 if (unlikely(!should_zap_folio(details, folio))) 1499 continue; 1500 /* 1501 * Both device private/exclusive mappings should only 1502 * work with anonymous page so far, so we don't need to 1503 * consider uffd-wp bit when zap. For more information, 1504 * see zap_install_uffd_wp_if_needed(). 1505 */ 1506 WARN_ON_ONCE(!vma_is_anonymous(vma)); 1507 rss[mm_counter(page)]--; 1508 if (is_device_private_entry(entry)) 1509 folio_remove_rmap_pte(folio, page, vma); 1510 folio_put(folio); 1511 } else if (!non_swap_entry(entry)) { 1512 /* Genuine swap entry, hence a private anon page */ 1513 if (!should_zap_cows(details)) 1514 continue; 1515 rss[MM_SWAPENTS]--; 1516 if (unlikely(!free_swap_and_cache(entry))) 1517 print_bad_pte(vma, addr, ptent, NULL); 1518 } else if (is_migration_entry(entry)) { 1519 folio = pfn_swap_entry_folio(entry); 1520 if (!should_zap_folio(details, folio)) 1521 continue; 1522 rss[mm_counter(&folio->page)]--; 1523 } else if (pte_marker_entry_uffd_wp(entry)) { 1524 /* 1525 * For anon: always drop the marker; for file: only 1526 * drop the marker if explicitly requested. 1527 */ 1528 if (!vma_is_anonymous(vma) && 1529 !zap_drop_file_uffd_wp(details)) 1530 continue; 1531 } else if (is_hwpoison_entry(entry) || 1532 is_poisoned_swp_entry(entry)) { 1533 if (!should_zap_cows(details)) 1534 continue; 1535 } else { 1536 /* We should have covered all the swap entry types */ 1537 pr_alert("unrecognized swap entry 0x%lx\n", entry.val); 1538 WARN_ON_ONCE(1); 1539 } 1540 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1541 zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent); 1542 } while (pte++, addr += PAGE_SIZE, addr != end); 1543 1544 add_mm_rss_vec(mm, rss); 1545 arch_leave_lazy_mmu_mode(); 1546 1547 /* Do the actual TLB flush before dropping ptl */ 1548 if (force_flush) { 1549 tlb_flush_mmu_tlbonly(tlb); 1550 tlb_flush_rmaps(tlb, vma); 1551 } 1552 pte_unmap_unlock(start_pte, ptl); 1553 1554 /* 1555 * If we forced a TLB flush (either due to running out of 1556 * batch buffers or because we needed to flush dirty TLB 1557 * entries before releasing the ptl), free the batched 1558 * memory too. Come back again if we didn't do everything. 1559 */ 1560 if (force_flush) 1561 tlb_flush_mmu(tlb); 1562 1563 return addr; 1564 } 1565 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
