INFO: task syz-fuzzer:7335 blocked for more than 140 seconds. Not tainted 4.14.166-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-fuzzer D26896 7335 7320 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384 schedule+0x92/0x1c0 kernel/sched/core.c:3428 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline] rwsem_down_read_failed+0x1f6/0x390 kernel/locking/rwsem-xadd.c:309 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:66 [inline] down_read+0x49/0xb0 kernel/locking/rwsem.c:26 __do_page_fault+0x894/0xb80 arch/x86/mm/fault.c:1356 do_page_fault+0x71/0x511 arch/x86/mm/fault.c:1495 page_fault+0x45/0x50 arch/x86/entry/entry_64.S:1122 RIP: 0033:0x40ff9e RSP: 002b:000000c4202fb8b0 EFLAGS: 00010246 RAX: 00007fbe8a1f76c8 RBX: 0000000000000000 RCX: 000000c4336cf000 RDX: 000000c42013b000 RSI: 0000000000000006 RDI: 0000000000000000 RBP: 000000c420301d18 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000003 R11: 000000c42969fb80 R12: 0000000000000101 R13: 0000000000000100 R14: 0000000000000200 R15: 0000000000000080 Showing all locks held in the system: 1 lock held by khungtaskd/1052: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544 2 locks held by kworker/0:2/2799: #0: ("events"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("events"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("events"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("events"){+.+.}, at: [] process_one_work+0x76e/0x1600 kernel/workqueue.c:2085 #1: ((&ns->proc_work)){+.+.}, at: [] process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089 2 locks held by getty/7301: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7302: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7303: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7304: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7305: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7306: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/8030: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 3 locks held by kworker/u4:7/8518: #0: ("%s""netns"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("%s""netns"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("%s""netns"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("%s""netns"){+.+.}, at: [] process_one_work+0x76e/0x1600 kernel/workqueue.c:2085 #1: (net_cleanup_work){+.+.}, at: [] process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089 #2: (net_mutex){+.+.}, at: [] cleanup_net+0x11c/0x870 net/core/net_namespace.c:450 2 locks held by kworker/0:0/8848: #0: ("events"){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("events"){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("events"){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("events"){+.+.}, at: [] process_one_work+0x76e/0x1600 kernel/workqueue.c:2085 #1: ((&ns->proc_work)){+.+.}, at: [] process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1052 Comm: khungtaskd Not tainted 4.14.166-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x142/0x197 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x141/0x189 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5e7/0xb90 kernel/hung_task.c:274 kthread+0x319/0x430 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 7324 Comm: syz-fuzzer Not tainted 4.14.166-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880a9970440 task.stack: ffff88808db40000 RIP: 0033:0x412124 RSP: 002b:000000c42004be38 EFLAGS: 00000246 RAX: 000000c420000000 RBX: 000000c436870de0 RCX: 000000c420000900 RDX: 000000000000b438 RSI: 00007fbe897eb568 RDI: 000000c436870000 RBP: 000000c42004be80 R08: 0000000000000001 R09: 000000000b58f4c0 R10: 0000000000000030 R11: 000000c436870de0 R12: 000000c43741c000 R13: 0000000000000017 R14: 0000000000000000 R15: 0000000000000000 FS: 000000c420040490(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c436db9010 CR3: 0000000091a40000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400