syzbot

EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.
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BUG: KCSAN: data-race in __lru_add_drain_all / folios_put_refs

write to 0xffff888237c266e8 of 1 bytes by task 9929 on cpu 0:
 folio_batch_reinit include/linux/folio_batch.h:50 [inline]
 folios_put_refs+0x28f/0x2d0 mm/swap.c:1002
 folios_put include/linux/mm.h:2149 [inline]
 folio_batch_move_lru+0x263/0x290 mm/swap.c:179
 __folio_batch_add_and_move mm/swap.c:196 [inline]
 folio_add_lru+0x149/0x1e0 mm/swap.c:517
 folio_add_lru_vma+0x49/0x70 mm/swap.c:536
 wp_page_copy mm/memory.c:3927 [inline]
 do_wp_page+0x13b1/0x2040 mm/memory.c:4320
 handle_pte_fault mm/memory.c:6427 [inline]
 __handle_mm_fault mm/memory.c:6549 [inline]
 handle_mm_fault+0x8b9/0x2e70 mm/memory.c:6718
 do_user_addr_fault+0x3fd/0x1050 arch/x86/mm/fault.c:1385
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
 __put_user_nocheck_4+0x3/0x10 arch/x86/lib/putuser.S:97
 ____sys_recvmsg+0x1a1/0x280 net/socket.c:2931
 ___sys_recvmsg+0x11f/0x3b0 net/socket.c:2960
 do_recvmmsg+0x1ef/0x560 net/socket.c:3055
 __sys_recvmmsg net/socket.c:3129 [inline]
 __do_sys_recvmmsg net/socket.c:3152 [inline]
 __se_sys_recvmmsg net/socket.c:3145 [inline]
 __x64_sys_recvmmsg+0xe5/0x170 net/socket.c:3145
 x64_sys_call+0x80f/0x3020 arch/x86/include/generated/asm/syscalls_64.h:300
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c266e8 of 1 bytes by task 8616 on cpu 1:
 folio_batch_count include/linux/folio_batch.h:56 [inline]
 cpu_needs_drain mm/swap.c:786 [inline]
 __lru_add_drain_all+0x17e/0x450 mm/swap.c:883
 lru_add_drain_all+0x10/0x20 mm/swap.c:899
 invalidate_bdev+0x47/0x70 block/bdev.c:101
 ext4_put_super+0x610/0x7b0 fs/ext4/super.c:1355
 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:7492
 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:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x232/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x1f -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8616 Comm: syz-executor Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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