syzbot

INFO: task syz-executor:4389 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:22224 pid:4389  ppid:1      flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 wb_wait_for_completion+0x16f/0x290 fs/fs-writeback.c:191
 sync_inodes_sb+0x1c5/0xa10 fs/fs-writeback.c:2756
 sync_filesystem+0x16d/0x220 fs/sync.c:64
 generic_shutdown_super+0x6b/0x340 fs/super.c:474
 kill_block_super+0x7c/0xe0 fs/super.c:1470
 deactivate_locked_super+0x93/0xf0 fs/super.c:332
 cleanup_mnt+0x471/0x4f0 fs/namespace.c:1191
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0x9d5/0x2570 kernel/exit.c:881
 do_group_exit+0x229/0x2e0 kernel/exit.c:1024
 __do_sys_exit_group kernel/exit.c:1035 [inline]
 __se_sys_exit_group kernel/exit.c:1033 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1033
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff6fe59de59
RSP: 002b:00007ffceb57e5a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007ff6fe63333c RCX: 00007ff6fe59de59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000010 R08: 0000000000000000 R09: 00007ff6fe6332ca
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffceb57f860
R13: 00007ff6fe6332ca R14: 00005555622724e8 R15: 00007ffceb580930
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u4:0/9:
3 locks held by kworker/u4:1/11:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2e4f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2ed10 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6527
4 locks held by kworker/u4:3/46:
5 locks held by kworker/u4:4/62:
3 locks held by kworker/u4:5/71:
3 locks held by kworker/u4:6/2974:
2 locks held by getty/4029:
 #0: ffff88802fed9098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
2 locks held by syz-executor/4389:
 #0: ffff8880763300e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff88802480a7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff88802480a7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by syz-executor/4448:
 #0: ffff888028a840e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff8881433687d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff8881433687d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by syz-executor/4470:
 #0: ffff88802067a0e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff88814336e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff88814336e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
4 locks held by kworker/u4:7/4485:
2 locks held by syz-executor/4487:
 #0: ffff8880183fe0e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff8881433747d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff8881433747d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by syz-executor/4505:
 #0: ffff88807d81e0e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff888143f1a7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff888143f1a7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by kworker/u4:9/4522:
2 locks held by syz-executor/4537:
 #0: ffff888027fe60e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff888143f307d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff888143f307d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by syz-executor/4561:
 #0: ffff88805d0ca0e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362
 #1: ffff8880247367d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff8880247367d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by dhcpcd/4586:
 #0: ffff888053432130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1805 [inline]
 #0: ffff888053432130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x33/0xd40 net/packet/af_packet.c:3255
 #1: ffffffff8cb33838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
 #1: ffffffff8cb33838 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2ec/0x890 kernel/rcu/tree_exp.h:962

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4522 Comm: kworker/u4:9 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:filter_irq_stacks+0x29/0x90 kernel/stacktrace.c:395
Code: 00 41 57 41 56 41 55 41 54 53 85 f6 74 70 49 89 fe 41 89 f4 31 db 49 bd 00 00 00 00 00 fc ff df 49 89 ff 4c 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 ff e8 38 69 62 00 49 8b 04 de 48 3d e0
RSP: 0018:ffffc900036e7728 EFLAGS: 00000a02
RAX: 1ffff920006dcf02 RBX: 000000000000000a RCX: 0000000000000801
RDX: 0000000000000001 RSI: 000000000000000c RDI: ffffc900036e77c0
RBP: ffffc900036e79f0 R08: 0000000000000001 R09: 000000000000000b
R10: dffffc0000000000 R11: fffff520006dcedd R12: 000000000000000c
R13: dffffc0000000000 R14: ffffc900036e77c0 R15: ffffc900036e7810
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005627339d3168 CR3: 0000000030b1b000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __stack_depot_save+0x35/0x480 lib/stackdepot.c:439
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_set_track+0x60/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x200 mm/slub.c:3700
 skb_free_head net/core/skbuff.c:762 [inline]
 skb_release_data+0x5e9/0x7e0 net/core/skbuff.c:791
 skb_release_all net/core/skbuff.c:856 [inline]
 __kfree_skb net/core/skbuff.c:870 [inline]
 consume_skb+0xa2/0x100 net/core/skbuff.c:1035
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:821 [inline]
 nsim_dev_trap_report_work+0x71f/0xa80 drivers/net/netdevsim/dev.c:851
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>