syzbot

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BUG: KCSAN: data-race in munlock_folio / need_mlock_drain

read-write to 0xffff888237d26610 of 1 bytes by task 4571 on cpu 1:
 folio_batch_add include/linux/pagevec.h:77 [inline]
 munlock_folio+0x44/0x120 mm/mlock.c:301
 munlock_vma_folio mm/internal.h:1025 [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:1525 [inline]
 zap_present_ptes mm/memory.c:1586 [inline]
 do_zap_pte_range mm/memory.c:1687 [inline]
 zap_pte_range mm/memory.c:1731 [inline]
 zap_pmd_range mm/memory.c:1823 [inline]
 zap_pud_range mm/memory.c:1852 [inline]
 zap_p4d_range mm/memory.c:1873 [inline]
 unmap_page_range+0xe28/0x27b0 mm/memory.c:1894
 unmap_single_vma+0x138/0x1d0 mm/memory.c:1940
 unmap_vmas+0x18a/0x2b0 mm/memory.c:1984
 exit_mmap+0x1b0/0x6c0 mm/mmap.c:1284
 __mmput+0x28/0x1c0 kernel/fork.c:1379
 mmput+0x40/0x50 kernel/fork.c:1401
 exit_mm+0xe4/0x190 kernel/exit.c:589
 do_exit+0x55f/0x17c0 kernel/exit.c:940
 do_group_exit+0x139/0x140 kernel/exit.c:1102
 __do_sys_exit_group kernel/exit.c:1113 [inline]
 __se_sys_exit_group kernel/exit.c:1111 [inline]
 __x64_sys_exit_group+0x1f/0x20 kernel/exit.c:1111
 x64_sys_call+0x2fa4/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237d26610 of 1 bytes by task 3303 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+0x220/0x3f0 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+0x624/0x7d0 fs/ext4/super.c:1343
 generic_shutdown_super+0xe3/0x210 fs/super.c:642
 kill_block_super+0x2a/0x70 fs/super.c:1710
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7393
 deactivate_locked_super+0x72/0x1c0 fs/super.c:473
 deactivate_super+0x97/0xa0 fs/super.c:506
 cleanup_mnt+0x269/0x2e0 fs/namespace.c:1435
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1442
 task_work_run+0x12e/0x1a0 kernel/task_work.c:227
 resume_user_mode_work+0x6a/0x70 include/linux/resume_user_mode.h:50
 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+0x77/0xb0 kernel/entry/common.c:218
 do_syscall_64+0xdd/0x1a0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0f -> 0x1c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3303 Comm: syz-executor Not tainted 6.15.0-rc4-syzkaller-00291-g2a239ffbebb5 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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