syzbot

INFO: task syz-executor:5834 blocked for more than 143 seconds.
      Not tainted 6.15.0-rc2-syzkaller-00257-gb5c6891b2c5b #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:20520 pid:5834  tgid:5834  ppid:1      task_flags:0x400140 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x1b88/0x5240 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6860
 __bch2_fs_stop+0x3cd/0x5b0 fs/bcachefs/super.c:650
 generic_shutdown_super+0x13b/0x2d0 fs/super.c:642
 bch2_kill_sb+0x41/0x50 fs/bcachefs/fs.c:2303
 deactivate_locked_super+0xc6/0x130 fs/super.c:473
 cleanup_mnt+0x422/0x4c0 fs/namespace.c:1435
 task_work_run+0x253/0x310 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 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+0x13f/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x210 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f618918f497
RSP: 002b:00007ffd111050a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f6189210854 RCX: 00007f618918f497
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd11105160
RBP: 00007ffd11105160 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffd111061f0
R13: 00007f6189210854 R14: 0000000000038ce1 R15: 00007ffd11106230
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8ed3df20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8ed3df20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8ed3df20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x30/0x180 kernel/locking/lockdep.c:6764
1 lock held by udevd/5204:
2 locks held by getty/5587:
 #0: ffff8880307a40a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900036be2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x5bb/0x1700 drivers/tty/n_tty.c:2222
1 lock held by syz-executor/5833:
1 lock held by syz-executor/5834:
 #0: ffff888027cde0e0 (&type->s_umount_key#78){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff888027cde0e0 (&type->s_umount_key#78){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff888027cde0e0 (&type->s_umount_key#78){+.+.}-{4:4}, at: deactivate_super+0xb5/0xf0 fs/super.c:505
3 locks held by kworker/u8:7/5918:
 #0: ffff8880b8639b18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:605
 #1: ffff8880b8623b08 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x41f/0x7a0 kernel/sched/psi.c:987
 #2: ffff8880258f70e0 (&lo->lo_work_lock){..-.}-{3:3}, at: spin_lock_irq include/linux/spinlock.h:376 [inline]
 #2: ffff8880258f70e0 (&lo->lo_work_lock){..-.}-{3:3}, at: loop_process_work+0x1c04/0x21d0 drivers/block/loop.c:1981
4 locks held by kworker/u8:9/8771:
2 locks held by syz-executor/10975:
 #0: ffff888032e5c0e0 (&type->s_umount_key#92){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff888032e5c0e0 (&type->s_umount_key#92){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff888032e5c0e0 (&type->s_umount_key#92){+.+.}-{4:4}, at: deactivate_super+0xb5/0xf0 fs/super.c:505
 #1: ffffffff8ed43300 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x530 kernel/rcu/tree.c:3774
1 lock held by syz.7.2290/12953:
 #0: ffffffff8ed43438 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:336 [inline]
 #0: ffffffff8ed43438 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x454/0x830 kernel/rcu/tree_exp.h:998
1 lock held by syz.9.2291/12956:
4 locks held by dhcpcd-run-hook/12966:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.15.0-rc2-syzkaller-00257-gb5c6891b2c5b #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x4ab/0x4e0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline]
 watchdog+0x1058/0x10a0 kernel/hung_task.c:437
 kthread+0x7b9/0x940 kernel/kthread.c:464
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 12710 Comm: udevd Not tainted 6.15.0-rc2-syzkaller-00257-gb5c6891b2c5b #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:hlock_class kernel/locking/lockdep.c:233 [inline]
RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:3821 [inline]
RIP: 0010:validate_chain+0x55/0x24e0 kernel/locking/lockdep.c:3877
Code: 89 c1 81 e1 00 80 04 00 81 f9 00 00 04 00 0f 85 4f 02 00 00 41 89 d4 49 89 f7 49 89 fe 25 ff 1f 00 00 48 0f a3 05 ab 3e d1 12 <72> 36 83 3d d2 cd d4 18 00 75 2d 90 e8 fa c4 61 03 85 c0 74 22 83
RSP: 0018:ffffc90000a08bb0 EFLAGS: 00000007
RAX: 0000000000000071 RBX: bc101d9a73125dae RCX: 0000000000040000
RDX: 0000000000000001 RSI: ffff88802d80c6f0 RDI: ffff88802d80bc00
RBP: bc101d9a73125dae R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: ffffffff93686020 R14: ffff88802d80bc00 R15: ffff88802d80c6f0
FS:  00007fdcbecc0c80(0000) GS:ffff88812509a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005652b6827950 CR3: 00000000428c2000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235
 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xd8/0x130 kernel/locking/spinlock.c:162
 hrtimer_interrupt+0xf9/0xa40 kernel/time/hrtimer.c:1868
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x112/0x420 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:console_trylock_spinning kernel/printk/printk.c:2061 [inline]
RIP: 0010:vprintk_emit+0x731/0xa40 kernel/printk/printk.c:2449
Code: 00 e8 d3 27 21 00 4c 8d bc 24 a0 00 00 00 4d 85 e4 75 07 e8 c1 27 21 00 eb 06 e8 ba 27 21 00 fb 49 bc 00 00 00 00 00 fc ff df <48> c7 c7 80 9a c1 8e 31 f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00
RSP: 0018:ffffc9000bc477e0 EFLAGS: 00000293
RAX: ffffffff81a19306 RBX: 0000000000000000 RCX: ffff88802d80bc00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000bc478f0 R08: ffffffff81a192df R09: 1ffffffff20bfcae
R10: dffffc0000000000 R11: fffffbfff20bfcaf R12: dffffc0000000000
R13: 1ffff92001788f00 R14: ffffffff81a19132 R15: ffffc9000bc47880
 devkmsg_emit+0xdc/0x130 kernel/printk/printk.c:755
 devkmsg_write+0x2a3/0x400 kernel/printk/printk.c:818
 do_iter_readv_writev+0x721/0x9d0 fs/read_write.c:-1
 vfs_writev+0x38d/0xbc0 fs/read_write.c:1055
 do_writev+0x1b8/0x360 fs/read_write.c:1101
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdcbe91ae03
Code: 89 c7 48 89 44 24 08 e8 6a f2 f9 ff 48 8b 44 24 08 48 83 c4 28 c3 c3 64 8b 04 25 18 00 00 00 85 c0 75 20 b8 14 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 6d 48 8b 15 f6 5f 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007fff0d2d2b98 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdcbe91ae03
RDX: 0000000000000005 RSI: 00007fff0d2d2c00 RDI: 0000000000000005
RBP: 00007fff0d2d2c00 R08: 00007fff0d2d2c77 R09: 00007fff0d2d2518
R10: 000000000000001e R11: 0000000000000246 R12: 000000000000001b
R13: 00007fff0d2d2d28 R14: 0000000000000000 R15: 00007fff0d2d2c88
 </TASK>