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Mon, 15 Dec 2025 22:30:29 -0800 (PST) Received: from localhost.localdomain ([114.231.217.195]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29ee9d38b98sm154247525ad.34.2025.12.15.22.30.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Dec 2025 22:30:29 -0800 (PST) Date: Tue, 16 Dec 2025 14:30:20 +0800 From: Vernon Yang To: kernel test robot Cc: akpm@linux-foundation.org, david@kernel.org, lorenzo.stoakes@oracle.com, llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev, ziy@nvidia.com, baohua@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vernon Yang Subject: Re: [PATCH 2/4] mm: khugepaged: remove mm when all memory has been collapsed Message-ID: References: <20251215090419.174418-3-yanglincheng@kylinos.cn> <202512160533.KuHwyJTP-lkp@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202512160533.KuHwyJTP-lkp@intel.com> X-Rspamd-Queue-Id: 5276980011 X-Rspamd-Server: rspam03 X-Stat-Signature: 9jqijysr3cz1rafu3dhp8m3fxx8opsy8 X-Rspam-User: X-HE-Tag: 1765866631-67642 X-HE-Meta: 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 nOn0f/Tc 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Dec 16, 2025 at 05:45:31AM +0800, kernel test robot wrote: > Hi Vernon, > > kernel test robot noticed the following build errors: > > [auto build test ERROR on akpm-mm/mm-everything] > [also build test ERROR on linus/master v6.19-rc1 next-20251215] > [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/Vernon-Yang/mm-khugepaged-add-trace_mm_khugepaged_scan-event/20251215-171046 > base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything > patch link: https://lore.kernel.org/r/20251215090419.174418-3-yanglincheng%40kylinos.cn > patch subject: [PATCH 2/4] mm: khugepaged: remove mm when all memory has been collapsed > config: x86_64-kexec (https://download.01.org/0day-ci/archive/20251216/202512160533.KuHwyJTP-lkp@intel.com/config) > compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261) > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251216/202512160533.KuHwyJTP-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 > | Closes: https://lore.kernel.org/oe-kbuild-all/202512160533.KuHwyJTP-lkp@intel.com/ > > All errors (new ones prefixed by >>): > > >> mm/khugepaged.c:2490:9: error: use of undeclared identifier 'SCAN_PMD_NULL'; did you mean 'SCAN_VMA_NULL'? > 2490 | case SCAN_PMD_NULL: > | ^~~~~~~~~~~~~ > | SCAN_VMA_NULL > mm/khugepaged.c:50:2: note: 'SCAN_VMA_NULL' declared here > 50 | SCAN_VMA_NULL, > | ^ > >> mm/khugepaged.c:2491:9: error: use of undeclared identifier 'SCAN_PMD_NONE' > 2491 | case SCAN_PMD_NONE: > | ^ > 2 errors generated. This series is based on Linux v6.18, due to the v6.19-rc1 add "mm/khugepaged: unify SCAN_PMD_NONE and SCAN_PMD_NULL into SCAN_NO_PTE_TABLE"[1], trigger this build errors. I'll fix it in the next version, Thanks! [1] https://lkml.kernel.org/r/20251114030028.7035-4-richard.weiyang@gmail.com > > vim +2490 mm/khugepaged.c > > 2392 > 2393 static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result, > 2394 struct collapse_control *cc) > 2395 __releases(&khugepaged_mm_lock) > 2396 __acquires(&khugepaged_mm_lock) > 2397 { > 2398 struct vma_iterator vmi; > 2399 struct mm_slot *slot; > 2400 struct mm_struct *mm; > 2401 struct vm_area_struct *vma; > 2402 int progress = 0; > 2403 > 2404 VM_BUG_ON(!pages); > 2405 lockdep_assert_held(&khugepaged_mm_lock); > 2406 *result = SCAN_FAIL; > 2407 > 2408 if (khugepaged_scan.mm_slot) { > 2409 slot = khugepaged_scan.mm_slot; > 2410 } else { > 2411 slot = list_first_entry(&khugepaged_scan.mm_head, > 2412 struct mm_slot, mm_node); > 2413 khugepaged_scan.address = 0; > 2414 khugepaged_scan.mm_slot = slot; > 2415 khugepaged_scan.maybe_collapse = false; > 2416 } > 2417 spin_unlock(&khugepaged_mm_lock); > 2418 > 2419 mm = slot->mm; > 2420 /* > 2421 * Don't wait for semaphore (to avoid long wait times). Just move to > 2422 * the next mm on the list. > 2423 */ > 2424 vma = NULL; > 2425 if (unlikely(!mmap_read_trylock(mm))) > 2426 goto breakouterloop_mmap_lock; > 2427 > 2428 progress++; > 2429 if (unlikely(hpage_collapse_test_exit_or_disable(mm))) > 2430 goto breakouterloop; > 2431 > 2432 vma_iter_init(&vmi, mm, khugepaged_scan.address); > 2433 for_each_vma(vmi, vma) { > 2434 unsigned long hstart, hend; > 2435 > 2436 cond_resched(); > 2437 if (unlikely(hpage_collapse_test_exit_or_disable(mm))) { > 2438 progress++; > 2439 break; > 2440 } > 2441 if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) { > 2442 skip: > 2443 progress++; > 2444 continue; > 2445 } > 2446 hstart = round_up(vma->vm_start, HPAGE_PMD_SIZE); > 2447 hend = round_down(vma->vm_end, HPAGE_PMD_SIZE); > 2448 if (khugepaged_scan.address > hend) > 2449 goto skip; > 2450 if (khugepaged_scan.address < hstart) > 2451 khugepaged_scan.address = hstart; > 2452 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); > 2453 > 2454 while (khugepaged_scan.address < hend) { > 2455 bool mmap_locked = true; > 2456 > 2457 cond_resched(); > 2458 if (unlikely(hpage_collapse_test_exit_or_disable(mm))) > 2459 goto breakouterloop; > 2460 > 2461 VM_BUG_ON(khugepaged_scan.address < hstart || > 2462 khugepaged_scan.address + HPAGE_PMD_SIZE > > 2463 hend); > 2464 if (!vma_is_anonymous(vma)) { > 2465 struct file *file = get_file(vma->vm_file); > 2466 pgoff_t pgoff = linear_page_index(vma, > 2467 khugepaged_scan.address); > 2468 > 2469 mmap_read_unlock(mm); > 2470 mmap_locked = false; > 2471 *result = hpage_collapse_scan_file(mm, > 2472 khugepaged_scan.address, file, pgoff, cc); > 2473 fput(file); > 2474 if (*result == SCAN_PTE_MAPPED_HUGEPAGE) { > 2475 mmap_read_lock(mm); > 2476 if (hpage_collapse_test_exit_or_disable(mm)) > 2477 goto breakouterloop; > 2478 *result = collapse_pte_mapped_thp(mm, > 2479 khugepaged_scan.address, false); > 2480 if (*result == SCAN_PMD_MAPPED) > 2481 *result = SCAN_SUCCEED; > 2482 mmap_read_unlock(mm); > 2483 } > 2484 } else { > 2485 *result = hpage_collapse_scan_pmd(mm, vma, > 2486 khugepaged_scan.address, &mmap_locked, cc); > 2487 } > 2488 > 2489 switch (*result) { > > 2490 case SCAN_PMD_NULL: > > 2491 case SCAN_PMD_NONE: > 2492 case SCAN_PMD_MAPPED: > 2493 case SCAN_PTE_MAPPED_HUGEPAGE: > 2494 break; > 2495 case SCAN_SUCCEED: > 2496 ++khugepaged_pages_collapsed; > 2497 fallthrough; > 2498 default: > 2499 khugepaged_scan.maybe_collapse = true; > 2500 } > 2501 > 2502 /* move to next address */ > 2503 khugepaged_scan.address += HPAGE_PMD_SIZE; > 2504 progress += HPAGE_PMD_NR; > 2505 if (!mmap_locked) > 2506 /* > 2507 * We released mmap_lock so break loop. Note > 2508 * that we drop mmap_lock before all hugepage > 2509 * allocations, so if allocation fails, we are > 2510 * guaranteed to break here and report the > 2511 * correct result back to caller. > 2512 */ > 2513 goto breakouterloop_mmap_lock; > 2514 if (progress >= pages) > 2515 goto breakouterloop; > 2516 } > 2517 } > 2518 breakouterloop: > 2519 mmap_read_unlock(mm); /* exit_mmap will destroy ptes after this */ > 2520 breakouterloop_mmap_lock: > 2521 > 2522 spin_lock(&khugepaged_mm_lock); > 2523 VM_BUG_ON(khugepaged_scan.mm_slot != slot); > 2524 /* > 2525 * Release the current mm_slot if this mm is about to die, or > 2526 * if we scanned all vmas of this mm. > 2527 */ > 2528 if (hpage_collapse_test_exit(mm) || !vma) { > 2529 bool maybe_collapse = khugepaged_scan.maybe_collapse; > 2530 > 2531 if (mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm)) > 2532 maybe_collapse = true; > 2533 > 2534 /* > 2535 * Make sure that if mm_users is reaching zero while > 2536 * khugepaged runs here, khugepaged_exit will find > 2537 * mm_slot not pointing to the exiting mm. > 2538 */ > 2539 if (!list_is_last(&slot->mm_node, &khugepaged_scan.mm_head)) { > 2540 khugepaged_scan.mm_slot = list_next_entry(slot, mm_node); > 2541 khugepaged_scan.address = 0; > 2542 khugepaged_scan.maybe_collapse = false; > 2543 } else { > 2544 khugepaged_scan.mm_slot = NULL; > 2545 khugepaged_full_scans++; > 2546 } > 2547 > 2548 collect_mm_slot(slot, maybe_collapse); > 2549 } > 2550 > 2551 trace_mm_khugepaged_scan(mm, progress, khugepaged_scan.mm_slot == NULL); > 2552 > 2553 return progress; > 2554 } > 2555 > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki -- Thanks, Vernon