syzbot

INFO: task syz.0.5942:23070 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.5942      state:D stack:26448 pid:23070 ppid:18144  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
 sync_bdevs+0x1af/0x330 block/bdev.c:1059
 ksys_sync+0xba/0x150 fs/sync.c:105
 __ia32_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f804458ebe9
RSP: 002b:00007f80453dd038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f80447b6090 RCX: 00007f804458ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f80447b6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f80447b6128 R14: 00007f80447b6090 R15: 00007ffd7e7190b8
 </TASK>

Showing all locks held in the system:
1 lock held by pool_workqueue_/3:
2 locks held by kworker/u4:1/12:
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2fbe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2fbe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2fbe0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
4 locks held by kworker/u4:5/1081:
 #0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000478fd00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000478fd00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffffffff8dfaf510 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x136/0xb90 net/core/net_namespace.c:606
 #3: ffffffff8cd35a80 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:4089
2 locks held by getty/5547:
 #0: ffff888030a5a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
1 lock held by udevd/18621:
 #0: ffff8880222174c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x121/0x600 block/bdev.c:788
1 lock held by udevd/19851:
 #0: ffff8880222124c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x121/0x600 block/bdev.c:788
1 lock held by syz.0.5942/23070:
 #0: ffff8880222174c8 (&disk->open_mutex){+.+.}-{3:3}, at: sync_bdevs+0x1af/0x330 block/bdev.c:1059
1 lock held by syz.6.6350/24737:

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

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf41/0xf80 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 2917 Comm: kworker/u4:7 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:check_region_inline mm/kasan/generic.c:169 [inline]
RIP: 0010:kasan_check_range+0x18/0x290 mm/kasan/generic.c:187
Code: ff c3 0f 0b b8 ea ff ff ff c3 cc cc cc cc cc cc cc cc 66 0f 1f 00 b0 01 48 85 f6 0f 84 b8 01 00 00 55 41 57 41 56 41 55 41 54 <53> 4c 8d 04 37 49 39 f8 0f 82 5a 02 00 00 49 89 f9 49 c1 e9 2f 41
RSP: 0018:ffffc9000be07370 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000003 RCX: ffffffff81670edc
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90da5500
RBP: ffffc9000be075e8 R08: dffffc0000000000 R09: 1ffffffff21b4aa0
R10: dffffc0000000000 R11: fffffbfff21b4aa1 R12: 0000000000000000
R13: ffff88802b542978 R14: 0000000000000008 R15: ffff88802b542978
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0893384198 CR3: 000000000cb30000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 hlock_class kernel/locking/lockdep.c:228 [inline]
 check_wait_context kernel/locking/lockdep.c:4798 [inline]
 __lock_acquire+0x94c/0x7c80 kernel/locking/lockdep.c:5087
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 __pte_offset_map_lock+0x107/0x1e0 mm/pgtable-generic.c:375
 get_locked_pte include/linux/mm.h:2686 [inline]
 __text_poke+0x29b/0xb20 arch/x86/kernel/alternative.c:2036
 text_poke arch/x86/kernel/alternative.c:2121 [inline]
 text_poke_bp_batch+0x4e4/0x930 arch/x86/kernel/alternative.c:2454
 text_poke_flush arch/x86/kernel/alternative.c:2623 [inline]
 text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2630
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 static_key_disable_cpuslocked+0xc5/0x1a0 kernel/jump_label.c:237
 static_key_disable+0x1a/0x20 kernel/jump_label.c:245
 toggle_allocation_gate+0x1b0/0x250 mm/kfence/core.c:836
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>