syzbot

INFO: task syz-executor:5845 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:22504 pid:5845  tgid:5845  ppid:1      task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 netfs_wait_for_outstanding_io include/linux/netfs.h:552 [inline]
 v9fs_evict_inode+0x26f/0x300 fs/9p/vfs_inode.c:348
 evict+0x3e6/0x920 fs/inode.c:810
 dispose_list+0x117/0x1e0 fs/inode.c:852
 evict_inodes+0x365/0x460 fs/inode.c:906
 generic_shutdown_super+0xb2/0x390 fs/super.c:628
 kill_anon_super+0x3a/0x60 fs/super.c:1282
 v9fs_kill_super+0x3d/0xa0 fs/9p/vfs_super.c:195
 deactivate_locked_super+0xbe/0x1a0 fs/super.c:474
 deactivate_super fs/super.c:507 [inline]
 deactivate_super+0xde/0x100 fs/super.c:503
 cleanup_mnt+0x225/0x450 fs/namespace.c:1375
 task_work_run+0x150/0x240 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xeb/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+0x41c/0x4e0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc8c33901f7
RSP: 002b:00007ffcd2eab7c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fc8c3411d7d RCX: 00007fc8c33901f7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffcd2eab880
RBP: 00007ffcd2eab880 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffcd2eac910
R13: 00007fc8c3411d7d R14: 00000000000349c7 R15: 00007ffcd2eac950
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_trace/29:
 #0: ffffffff8e5c0a10 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{4:4}, at: rcu_tasks_one_gp+0x72d/0xe20 kernel/rcu/tasks.h:614
1 lock held by khungtaskd/31:
 #0: ffffffff8e5c15a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e5c15a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e5c15a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by getty/5604:
 #0: ffff8880360e60a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
1 lock held by syz-executor/5845:
 #0: ffff88805c2fe0e0 (&type->s_umount_key#76){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff88805c2fe0e0 (&type->s_umount_key#76){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff88805c2fe0e0 (&type->s_umount_key#76){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline]
 #0: ffff88805c2fe0e0 (&type->s_umount_key#76){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:503
1 lock held by syz.2.910/10228:
 #0: ffffffff8e5cca00 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x48/0x6e0 kernel/rcu/tree.c:3815
1 lock held by syz.2.910/10239:
 #0: ffffffff8e5ccb38 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a3/0x3c0 kernel/rcu/tree_exp.h:343

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/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+0xf0e/0x1260 kernel/hung_task.c:491
 kthread+0x3c2/0x780 kernel/kthread.c:463
 ret_from_fork+0x56a/0x730 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: 8177 Comm: kworker/u8:42 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:debug_lockdep_rcu_enabled+0x0/0x40 kernel/rcu/update.c:319
Code: 00 00 00 eb b6 e8 30 fa ff ff eb b6 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 8b 05 16 88 16 05 85 c0 74 20 8b 05 e0 b8 16 05 85 c0
RSP: 0018:ffffc9000530fb18 EFLAGS: 00000286
RAX: 0000000000000000 RBX: ffff88803308cb00 RCX: 000000003777691b
RDX: 0000000000000000 RSI: ffffffff8de2d8f8 RDI: ffffffff8c163400
RBP: 0000000000000160 R08: e87279e147327434 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8881246b2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b320edff8 CR3: 0000000077770000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 rcu_read_lock include/linux/rcupdate.h:842 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
 batadv_nc_worker+0x16f/0x1030 net/batman-adv/network-coding.c:719
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c2/0x780 kernel/kthread.c:463
 ret_from_fork+0x56a/0x730 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>