syzbot

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BUG: KCSAN: data-race in munlock_folio / need_mlock_drain

read-write to 0xffff888237d2b4a8 of 1 bytes by task 7106 on cpu 1:
 folio_batch_add include/linux/pagevec.h:77 [inline]
 munlock_folio+0x42/0x130 mm/mlock.c:301
 munlock_vma_folio mm/internal.h:957 [inline]
 __folio_remove_rmap mm/rmap.c:1603 [inline]
 folio_remove_rmap_ptes+0x18f/0x1a0 mm/rmap.c:1620
 zap_present_folio_ptes mm/memory.c:1535 [inline]
 zap_present_ptes mm/memory.c:1596 [inline]
 do_zap_pte_range mm/memory.c:1698 [inline]
 zap_pte_range mm/memory.c:1742 [inline]
 zap_pmd_range mm/memory.c:1834 [inline]
 zap_pud_range mm/memory.c:1863 [inline]
 zap_p4d_range mm/memory.c:1884 [inline]
 unmap_page_range+0x10c5/0x2660 mm/memory.c:1905
 unmap_single_vma+0x142/0x1d0 mm/memory.c:1951
 unmap_vmas+0x18d/0x2b0 mm/memory.c:1995
 exit_mmap+0x1ae/0x6d0 mm/mmap.c:1284
 __mmput+0x28/0x1d0 kernel/fork.c:1356
 mmput+0x4c/0x60 kernel/fork.c:1378
 exit_mm+0xe4/0x190 kernel/exit.c:570
 do_exit+0x559/0x17f0 kernel/exit.c:925
 do_group_exit+0x102/0x150 kernel/exit.c:1087
 get_signal+0xeb9/0x1000 kernel/signal.c:3036
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x62/0x120 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237d2b4a8 of 1 bytes by task 6385 on cpu 0:
 folio_batch_count include/linux/pagevec.h:56 [inline]
 need_mlock_drain+0x30/0x50 mm/mlock.c:235
 cpu_needs_drain mm/swap.c:779 [inline]
 __lru_add_drain_all+0x22a/0x3f0 mm/swap.c:867
 lru_add_drain_all+0x10/0x20 mm/swap.c:883
 invalidate_bdev+0x47/0x70 block/bdev.c:101
 ext4_put_super+0x571/0x810 fs/ext4/super.c:1356
 generic_shutdown_super+0xe5/0x220 fs/super.c:642
 kill_block_super+0x2a/0x70 fs/super.c:1710
 ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7368
 deactivate_locked_super+0x7d/0x1c0 fs/super.c:473
 deactivate_super+0x9f/0xb0 fs/super.c:506
 cleanup_mnt+0x268/0x2e0 fs/namespace.c:1413
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1420
 task_work_run+0x13a/0x1a0 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xa8/0x120 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6385 Comm: syz-executor Not tainted 6.14.0-rc6-syzkaller-00205-g3571e8b091f4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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