syzbot

INFO: task syz-executor:27480 blocked for more than 143 seconds.
      Tainted: G        W           syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:21928 pid:27480 tgid:27480 ppid:1      task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x16f3/0x4c20 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 bch2_fs_read_only+0x2f2/0xb00 fs/bcachefs/super.c:358
 __bch2_fs_stop+0x100/0x900 fs/bcachefs/super.c:677
 generic_shutdown_super+0x132/0x2c0 fs/super.c:643
 bch2_kill_sb+0x41/0x50 fs/bcachefs/fs.c:2618
 deactivate_locked_super+0xbc/0x130 fs/super.c:474
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1375
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x110 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+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa5f075ff17
RSP: 002b:00007ffcf368a4b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fa5f07e1c05 RCX: 00007fa5f075ff17
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffcf368a570
RBP: 00007ffcf368a570 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffcf368b600
R13: 00007fa5f07e1c05 R14: 000000000016fc13 R15: 00007ffcf368b640
 </TASK>
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Tainted: G        W           syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf93/0xfe0 kernel/hung_task.c:491
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 1401 Comm: kworker/u8:39 Tainted: G        W           syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: bat_events batadv_tt_purge
RIP: 0010:debug_spin_lock_before kernel/locking/spinlock_debug.c:88 [inline]
RIP: 0010:do_raw_spin_lock+0xc8/0x290 kernel/locking/spinlock_debug.c:115
Code: 43 80 3c 3e 00 74 08 4c 89 e7 e8 23 e3 80 00 49 8b 04 24 65 48 8b 0c 25 08 c0 f5 91 48 89 4c 24 10 48 39 c8 0f 84 07 01 00 00 <4c> 8d 6b 08 4d 89 ef 49 c1 ef 03 48 b8 00 00 00 00 00 fc ff df 41
RSP: 0018:ffffc90005de7640 EFLAGS: 00000006
RAX: ffffffffffffffff RBX: ffff8880b8823d38 RCX: ffff888027a19dc0
RDX: 0000000000000000 RSI: ffffffff8b620c60 RDI: ffff8880b8823d38
RBP: ffffc90005de76f0 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1e3a7c7 R12: ffff8880b8823d48
R13: ffffc90005de77e8 R14: 1ffff110171047a9 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8881268c4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f4247b6168 CR3: 000000000d7a6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
 _raw_spin_lock_irqsave+0xb3/0xf0 kernel/locking/spinlock.c:162
 rtlock_slowlock kernel/locking/rtmutex.c:1894 [inline]
 rtlock_lock kernel/locking/spinlock_rt.c:43 [inline]
 __rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline]
 rt_spin_lock+0x144/0x2c0 kernel/locking/spinlock_rt.c:57
 spin_lock include/linux/spinlock_rt.h:44 [inline]
 __local_bh_disable_ip+0x264/0x400 kernel/softirq.c:168
 local_bh_disable include/linux/bottom_half.h:20 [inline]
 spin_lock_bh include/linux/spinlock_rt.h:87 [inline]
 batadv_tt_local_purge+0x136/0x380 net/batman-adv/translation-table.c:1313
 batadv_tt_purge+0x35/0xa10 net/batman-adv/translation-table.c:3509
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>