INFO: task kworker/u4:4:148 blocked for more than 143 seconds. Not tainted 5.8.0-rc3-next-20200703-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:4 D24472 148 2 0x00004000 Workqueue: netns cleanup_net Call Trace: context_switch kernel/sched/core.c:3445 [inline] __schedule+0x8b4/0x1e80 kernel/sched/core.c:4169 schedule+0xd0/0x2a0 kernel/sched/core.c:4244 schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1873 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x163/0x260 kernel/sched/completion.c:138 start_unregistering fs/proc/proc_sysctl.c:288 [inline] drop_sysctl_table+0x41d/0x4e0 fs/proc/proc_sysctl.c:1639 unregister_sysctl_table fs/proc/proc_sysctl.c:1681 [inline] unregister_sysctl_table+0xbd/0x190 fs/proc/proc_sysctl.c:1656 ip_vs_control_net_cleanup_sysctl net/netfilter/ipvs/ip_vs_ctl.c:4098 [inline] ip_vs_control_net_cleanup+0x239/0x4f0 net/netfilter/ipvs/ip_vs_ctl.c:4167 __ip_vs_cleanup_batch+0x95/0x120 net/netfilter/ipvs/ip_vs_core.c:2480 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:189 cleanup_net+0x4ea/0xa00 net/core/net_namespace.c:603 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Showing all locks held in the system: 3 locks held by kworker/u4:4/148: #0: ffff8880a9771938 ((wq_completion)netns){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff8880a9771938 ((wq_completion)netns){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff8880a9771938 ((wq_completion)netns){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff8880a9771938 ((wq_completion)netns){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff8880a9771938 ((wq_completion)netns){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff8880a9771938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x82b/0x1670 kernel/workqueue.c:2240 #1: ffffc90000ff7da8 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x85f/0x1670 kernel/workqueue.c:2244 #2: ffffffff8a7ad5b0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x9b/0xa00 net/core/net_namespace.c:565 1 lock held by khungtaskd/1152: #0: ffffffff89bc3040 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5779 2 locks held by in:imklog/6464: #0: ffff8880a22120f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:928 #1: ffffffff89bb7a98 (logbuf_lock){-...}-{2:2}, at: is_bpf_text_address+0x0/0x160 kernel/bpf/core.c:691 1 lock held by syz-executor.0/26889: #0: ffffffff8a7ad5b0 (pernet_ops_rwsem){++++}-{3:3}, at: register_netdevice_notifier+0x1e/0x260 net/core/dev.c:1814 1 lock held by syz-executor.0/26934: #0: ffffffff8a7ad5b0 (pernet_ops_rwsem){++++}-{3:3}, at: register_netdevice_notifier+0x1e/0x260 net/core/dev.c:1814 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1152 Comm: khungtaskd Not tainted 5.8.0-rc3-next-20200703-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+0x18f/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline] watchdog+0xd89/0xf30 kernel/hung_task.c:339 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.8.0-rc3-next-20200703-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events nsim_dev_trap_report_work RIP: 0010:lockdep_recursion_finish kernel/locking/lockdep.c:398 [inline] RIP: 0010:lock_acquire+0x21a/0xad0 kernel/locking/lockdep.c:4961 Code: ff 48 b8 00 00 00 00 00 fc ff df 65 48 8b 1c 25 c0 fe 01 00 48 8d bb d4 08 00 00 48 83 c4 20 48 89 fa 48 c1 ea 03 0f b6 14 02 <48> 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 3a 07 00 00 83 RSP: 0018:ffffc90000d2f708 EFLAGS: 00000803 RAX: dffffc0000000000 RBX: ffff8880a95ee300 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff8880a95eebd4 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8c5a7a27 R10: fffffbfff18b4f44 R11: 0000000000000000 R12: 0000000000000000 R13: ffff88812fffbcd8 R14: 0000000000000000 R15: ffff8880a95ee300 FS: 0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb5dbf18000 CR3: 000000009354a000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:159 rmqueue mm/page_alloc.c:3380 [inline] get_page_from_freelist+0x16b6/0x3770 mm/page_alloc.c:3814 __alloc_pages_nodemask+0x291/0x700 mm/page_alloc.c:4867 __alloc_pages include/linux/gfp.h:509 [inline] __alloc_pages_node include/linux/gfp.h:522 [inline] kmem_getpages mm/slab.c:1376 [inline] cache_grow_begin+0x89/0x440 mm/slab.c:2594 cache_alloc_refill+0x27b/0x340 mm/slab.c:2966 ____cache_alloc mm/slab.c:3049 [inline] ____cache_alloc mm/slab.c:3032 [inline] slab_alloc_node mm/slab.c:3245 [inline] kmem_cache_alloc_node_trace+0x4fc/0x590 mm/slab.c:3596 __do_kmalloc_node mm/slab.c:3618 [inline] __kmalloc_node_track_caller+0x38/0x60 mm/slab.c:3633 __kmalloc_reserve net/core/skbuff.c:142 [inline] __alloc_skb+0xae/0x550 net/core/skbuff.c:210 alloc_skb include/linux/skbuff.h:1084 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:500 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:557 [inline] nsim_dev_trap_report_work+0x2b2/0xbe0 drivers/net/netdevsim/dev.c:598 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294