INFO: task kworker/u4:5:354 blocked for more than 143 seconds. Not tainted 5.7.0-rc4-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:5 D25360 354 2 0x80004000 Workqueue: netns cleanup_net Call Trace: context_switch kernel/sched/core.c:3367 [inline] __schedule+0x805/0xc90 kernel/sched/core.c:4083 schedule+0x188/0x220 kernel/sched/core.c:4158 schedule_timeout+0x43/0x250 kernel/time/timer.c:1874 mark_held_locks kernel/locking/lockdep.c:3628 [inline] __trace_hardirqs_on_caller kernel/locking/lockdep.c:3657 [inline] lockdep_hardirqs_on+0x4a4/0x8a0 kernel/locking/lockdep.c:3702 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline] _raw_spin_unlock_irq+0x1f/0x80 kernel/locking/spinlock.c:199 do_wait_for_common+0x232/0x370 kernel/sched/completion.c:85 console_conditional_schedule+0x30/0x30 __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x43/0x50 kernel/sched/completion.c:138 __flush_work+0xca/0x120 kernel/workqueue.c:3045 start_flush_work+0x730/0x730 kernel/workqueue.c:3017 flush_all_backlogs net/core/dev.c:5527 [inline] rollback_registered_many+0x6ac/0x1450 net/core/dev.c:8813 unregister_netdevice_many+0x46/0x260 net/core/dev.c:9988 vti6_exit_batch_net+0x3a3/0x3e0 net/ipv6/ip6_vti.c:1171 vti6_exit_batch_net+0x3b4/0x3e0 net/ipv6/ip6_vti.c:1175 vti6_init_net+0x2c0/0x2c0 net/ipv6/ip6_vti.c:954 ops_exit_list net/core/net_namespace.c:189 [inline] cleanup_net+0x78c/0xb80 net/core/net_namespace.c:603 process_one_work+0x76e/0xfd0 kernel/workqueue.c:2268 worker_thread+0xa7f/0x1450 kernel/workqueue.c:2414 kthread+0x353/0x380 kernel/kthread.c:268 rcu_lock_release+0x20/0x20 include/linux/rcupdate.h:213 kthread_blkcg+0xd0/0xd0 kernel/kthread.c:1247 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Showing all locks held in the system: 5 locks held by kworker/u4:5/354: #0: ffff8880a9bb4938 ((wq_completion)netns){+.+.}-{0:0}, at: spin_unlock_irq include/linux/spinlock.h:403 [inline] #0: ffff8880a9bb4938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x6df/0xfd0 kernel/workqueue.c:2241 #1: ffffc900020b7d80 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x71e/0xfd0 kernel/workqueue.c:2243 #2: ffffffff895ac230 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0xac/0xb80 net/core/net_namespace.c:565 #3: ffffffff895adf18 (rtnl_mutex){+.+.}-{3:3}, at: vti6_exit_batch_net+0x72/0x3e0 net/ipv6/ip6_vti.c:1170 #4: ffffffff892d8658 (cpu_hotplug_lock){++++}-{0:0}, at: get_online_cpus include/linux/cpu.h:143 [inline] #4: ffffffff892d8658 (cpu_hotplug_lock){++++}-{0:0}, at: flush_all_backlogs net/core/dev.c:5520 [inline] #4: ffffffff892d8658 (cpu_hotplug_lock){++++}-{0:0}, at: rollback_registered_many+0x4dd/0x1450 net/core/dev.c:8813 1 lock held by khungtaskd/1142: #0: ffffffff892e8550 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 net/mptcp/pm_netlink.c:860 3 locks held by kworker/1:15/2804: #0: ffff888214d0f538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: spin_unlock_irq include/linux/spinlock.h:403 [inline] #0: ffff888214d0f538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x6df/0xfd0 kernel/workqueue.c:2241 #1: ffffc9000810fd80 ((addr_chk_work).work){+.+.}-{0:0}, at: process_one_work+0x71e/0xfd0 kernel/workqueue.c:2243 #2: ffffffff895adf18 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4584 1 lock held by in:imklog/6920: #0: ffff8880a66c3170 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x25d/0x2f0 fs/file.c:826 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1142 Comm: khungtaskd Not tainted 5.7.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1e9/0x30e lib/dump_stack.c:118 nmi_cpu_backtrace+0x9f/0x180 lib/nmi_backtrace.c:101 arch_trigger_cpumask_backtrace+0x10/0x10 arch/x86/kernel/apic/hw_nmi.c:38 nmi_trigger_cpumask_backtrace+0x16a/0x280 lib/nmi_backtrace.c:62 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xd2a/0xd40 kernel/hung_task.c:289 kthread+0x353/0x380 kernel/kthread.c:268 hungtask_pm_notify+0x50/0x50 kernel/hung_task.c:265 kthread_blkcg+0xd0/0xd0 kernel/kthread.c:1247 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 15767 Comm: syz-executor.1 Not tainted 5.7.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:check_kcov_mode kernel/kcov.c:164 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x22/0x50 kernel/kcov.c:187 Code: 00 cc cc cc cc cc cc cc 48 8b 04 24 65 48 8b 0c 25 40 1e 02 00 65 8b 15 88 bc 8e 7e f7 c2 00 01 1f 00 75 2c 8b 91 d8 13 00 00 <83> fa 02 75 21 48 8b 91 e0 13 00 00 48 8b 32 48 8d 7e 01 8b 89 dc RSP: 0018:ffffc90003f8fd78 EFLAGS: 00000246 RAX: ffffffff81d374d8 RBX: ffff8880a3013110 RCX: ffff88804cf9e340 RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000282 RBP: ffff8880a3013160 R08: dffffc0000000000 R09: ffffed1014602661 R10: ffffed1014602661 R11: 0000000000000000 R12: dffffc0000000000 R13: ffff8880a925ba28 R14: 1ffff11014602622 R15: 1ffff1101460262c FS: 00000000027a0940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000073e694 CR3: 0000000093ec4000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: io_ring_ctx_wait_and_kill+0xd8/0x820 fs/io_uring.c:7333 io_uring_flush+0xbb0/0xbb0 fs/io_uring.c:7427 io_uring_release+0x59/0x70 fs/io_uring.c:7356 __fput+0x2ed/0x750 fs/file_table.c:280 task_work_run+0x147/0x1d0 kernel/task_work.c:123 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:165 [inline] prepare_exit_to_usermode+0x48e/0x600 arch/x86/entry/common.c:196 syscall_return_slowpath+0xf9/0x420 arch/x86/entry/common.c:278 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x416421 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007ffc4f631000 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000416421 RDX: 0000000000000000 RSI: 0000000000001afc RDI: 0000000000000004 RBP: 0000000000000001 R08: 00000000d9743afc R09: 00000000d9743b00 R10: 00007ffc4f6310f0 R11: 0000000000000293 R12: 000000000078c900 R13: 000000000078c900 R14: ffffffffffffffff R15: 000000000078bf0c