syzbot

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BUG: KCSAN: data-race in __lru_add_drain_all / folios_put_refs

write to 0xffff888237d26668 of 1 bytes by task 3298 on cpu 1:
 folio_batch_reinit include/linux/pagevec.h:50 [inline]
 folios_put_refs+0x285/0x2d0 mm/swap.c:996
 folios_put include/linux/mm.h:1876 [inline]
 folio_batch_move_lru+0x247/0x270 mm/swap.c:179
 lru_add_drain_cpu+0x66/0x210 mm/swap.c:648
 lru_add_drain mm/swap.c:737 [inline]
 __folio_batch_release+0x44/0xb0 mm/swap.c:1059
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x327/0xb10 mm/shmem.c:1149
 shmem_truncate_range mm/shmem.c:1277 [inline]
 shmem_evict_inode+0x12e/0x510 mm/shmem.c:1407
 evict+0x2af/0x510 fs/inode.c:846
 iput_final fs/inode.c:1966 [inline]
 iput+0x41a/0x580 fs/inode.c:2015
 dentry_unlink_inode+0x24f/0x260 fs/dcache.c:467
 __dentry_kill+0x13f/0x460 fs/dcache.c:670
 finish_dput+0x2b/0x200 fs/dcache.c:879
 dput+0x52/0x60 fs/dcache.c:928
 end_renaming fs/namei.c:4096 [inline]
 filename_renameat2+0x493/0x6e0 fs/namei.c:6146
 __do_sys_rename fs/namei.c:6188 [inline]
 __se_sys_rename+0x4a/0x1c0 fs/namei.c:6184
 __x64_sys_rename+0x31/0x40 fs/namei.c:6184
 x64_sys_call+0x2b3/0x3020 arch/x86/include/generated/asm/syscalls_64.h:83
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237d26668 of 1 bytes by task 3318 on cpu 0:
 folio_batch_count include/linux/pagevec.h:56 [inline]
 cpu_needs_drain mm/swap.c:780 [inline]
 __lru_add_drain_all+0x17e/0x450 mm/swap.c:877
 lru_add_drain_all+0x10/0x20 mm/swap.c:893
 invalidate_bdev+0x47/0x70 block/bdev.c:101
 ext4_put_super+0x624/0x7d0 fs/ext4/super.c:1353
 generic_shutdown_super+0xee/0x220 fs/super.c:646
 kill_block_super+0x2a/0x70 fs/super.c:1725
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7459
 deactivate_locked_super+0x75/0x1c0 fs/super.c:476
 deactivate_super+0x97/0xa0 fs/super.c:509
 cleanup_mnt+0x2bb/0x330 fs/namespace.c:1312
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1319
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x1f4/0x6f0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x15 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3318 Comm: syz-executor Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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