syzbot

EXT4-fs (loop1): unmounting filesystem 00000000-0000-0000-0000-000000000900.
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BUG: KCSAN: data-race in munlock_folio / need_mlock_drain

read-write to 0xffff888237c26a48 of 1 bytes by task 15351 on cpu 0:
 folio_batch_add include/linux/pagevec.h:77 [inline]
 munlock_folio+0x44/0x120 mm/mlock.c:301
 munlock_vma_folio mm/internal.h:1055 [inline]
 __folio_remove_rmap mm/rmap.c:1787 [inline]
 folio_remove_rmap_ptes+0x197/0x1a0 mm/rmap.c:1804
 zap_present_folio_ptes mm/memory.c:1523 [inline]
 zap_present_ptes mm/memory.c:1581 [inline]
 do_zap_pte_range mm/memory.c:1682 [inline]
 zap_pte_range mm/memory.c:1726 [inline]
 zap_pmd_range mm/memory.c:1818 [inline]
 zap_pud_range mm/memory.c:1847 [inline]
 zap_p4d_range mm/memory.c:1868 [inline]
 unmap_page_range+0x155b/0x2680 mm/memory.c:1889
 unmap_single_vma mm/memory.c:1932 [inline]
 unmap_vmas+0x23d/0x3a0 mm/memory.c:1976
 exit_mmap+0x1b0/0x6c0 mm/mmap.c:1280
 __mmput+0x28/0x1c0 kernel/fork.c:1130
 mmput+0x40/0x50 kernel/fork.c:1152
 exit_mm+0xe4/0x190 kernel/exit.c:582
 do_exit+0x417/0x15c0 kernel/exit.c:949
 do_group_exit+0xff/0x140 kernel/exit.c:1102
 get_signal+0xe59/0xf70 kernel/signal.c:3034
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x7a/0x100 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c26a48 of 1 bytes by task 10841 on cpu 1:
 folio_batch_count include/linux/pagevec.h:56 [inline]
 need_mlock_drain+0x30/0x50 mm/mlock.c:235
 cpu_needs_drain mm/swap.c:784 [inline]
 __lru_add_drain_all+0x220/0x3f0 mm/swap.c:872
 lru_add_drain_all+0x10/0x20 mm/swap.c:888
 invalidate_bdev+0x47/0x70 block/bdev.c:101
 ext4_put_super+0x624/0x7d0 fs/ext4/super.c:1339
 generic_shutdown_super+0xe6/0x210 fs/super.c:643
 kill_block_super+0x2a/0x70 fs/super.c:1766
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7395
 deactivate_locked_super+0x72/0x1c0 fs/super.c:474
 deactivate_super+0x97/0xa0 fs/super.c:507
 cleanup_mnt+0x269/0x2e0 fs/namespace.c:1375
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1382
 task_work_run+0x131/0x1a0 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xe4/0x100 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0d -> 0x16

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 10841 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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