INFO: task syz-executor0:27665 blocked for more than 120 seconds. Not tainted 4.16.0-rc3+ #240 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D23152 27665 4302 0x20020004 Call Trace: context_switch kernel/sched/core.c:2862 [inline] __schedule+0x905/0x2070 kernel/sched/core.c:3440 schedule+0xf5/0x430 kernel/sched/core.c:3499 io_schedule+0x1c/0x70 kernel/sched/core.c:5115 wait_on_page_bit_common+0x4b3/0x770 mm/filemap.c:1099 wait_on_page_bit mm/filemap.c:1132 [inline] wait_on_page_writeback include/linux/pagemap.h:546 [inline] __filemap_fdatawait_range+0x282/0x430 mm/filemap.c:533 filemap_fdatawait_keep_errors+0x2a/0xb0 mm/filemap.c:600 fdatawait_one_bdev+0x50/0x70 fs/sync.c:95 iterate_bdevs+0x109/0x260 fs/block_dev.c:2147 sys_sync+0x120/0x1c0 fs/sync.c:117 do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7fc7c99 RSP: 002b:00000000f77c309c EFLAGS: 00000286 ORIG_RAX: 0000000000000024 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/799: #0: (rcu_read_lock){....}, at: [<00000000f2eac92a>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000f2eac92a>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000ae7d68ab>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 2 locks held by getty/4220: #0: (&tty->ldisc_sem){++++}, at: [<000000009b0645f7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000e55a519b>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4221: #0: (&tty->ldisc_sem){++++}, at: [<000000009b0645f7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000e55a519b>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4222: #0: (&tty->ldisc_sem){++++}, at: [<000000009b0645f7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000e55a519b>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4223: #0: (&tty->ldisc_sem){++++}, at: [<000000009b0645f7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000e55a519b>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4224: #0: (&tty->ldisc_sem){++++}, at: [<000000009b0645f7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000e55a519b>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4225: #0: (&tty->ldisc_sem){++++}, at: [<000000009b0645f7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000e55a519b>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/13403: #0: (&tty->ldisc_sem){++++}, at: [<000000009b0645f7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000e55a519b>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 3 locks held by kworker/u4:32/25342: #0: ((wq_completion)"writeback"){+.+.}, at: [<00000000679e55f4>] process_one_work+0xaaf/0x1af0 kernel/workqueue.c:2084 #1: ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: [<00000000bf57617a>] process_one_work+0xb01/0x1af0 kernel/workqueue.c:2088 #2: (&type->s_umount_key#27){.+.+}, at: [<0000000050a701df>] trylock_super+0x20/0x100 fs/super.c:395 1 lock held by syz-executor0/27665: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000f095d2d4>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2145 1 lock held by syz-executor6/27685: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000b46a667b>] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 1 lock held by syz-executor6/27687: #0: (&bdev->bd_mutex){+.+.}, at: [<00000000b46a667b>] __blkdev_get+0x158/0x10e0 fs/block_dev.c:1439 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 799 Comm: khungtaskd Not tainted 4.16.0-rc3+ #240 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+0x194/0x24d lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x122/0x180 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:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:407 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 4095 Comm: rsyslogd Not tainted 4.16.0-rc3+ #240 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:trace_hardirqs_off_caller+0xb0/0x2c0 kernel/locking/lockdep.c:2910 RSP: 0018:ffff8801b95df7e0 EFLAGS: 00000046 RAX: dffffc0000000000 RBX: ffff8801ba9ce140 RCX: ffff8801b95df860 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff885d3300 RBP: ffff8801b95df7f8 R08: 0000000000000000 R09: 1ffff100372bbee7 R10: 0000000000000000 R11: 0000000000000001 R12: ffff8801ba9ce140 R13: ffffffff85ca23f4 R14: ffff8801b95dfa88 R15: ffffffff86f39520 FS: 00007f772931d700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000008113184 CR3: 00000001cc0ff004 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: trace_hardirqs_off+0xd/0x10 kernel/locking/lockdep.c:2928 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline] _raw_spin_lock_irqsave+0x74/0xc0 kernel/locking/spinlock.c:152 prepare_to_wait_event+0xc4/0xba0 kernel/sched/wait.c:270 do_syslog+0x96c/0xb80 kernel/printk/printk.c:1455 kmsg_read+0x74/0xa0 fs/proc/kmsg.c:40 proc_reg_read+0xe8/0x160 fs/proc/inode.c:218 __vfs_read+0xef/0xa00 fs/read_write.c:411 vfs_read+0x11e/0x350 fs/read_write.c:447 SYSC_read fs/read_write.c:573 [inline] SyS_read+0xef/0x220 fs/read_write.c:566 do_syscall_64+0x280/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x7f772bd7d1fd RSP: 002b:00007f772931ce30 EFLAGS: 00000293 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00000000014234b0 RCX: 00007f772bd7d1fd RDX: 0000000000000fff RSI: 00007f772ab515a0 RDI: 0000000000000004 RBP: 0000000000000000 R08: 000000000140e260 R09: 0000000004000001 R10: 0000000000000001 R11: 0000000000000293 R12: 000000000065e420 R13: 00007f772931d9c0 R14: 00007f772c3c2040 R15: 0000000000000003 Code: 7c 08 84 d2 0f 85 ce 01 00 00 41 8b b4 24 74 08 00 00 85 f6 0f 85 19 01 00 00 48 c7 c7 00 33 5d 88 48 b8 00 00 00 00 00 fc ff df <48> 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38