INFO: task syz-executor.4:2113 blocked for more than 140 seconds. Not tainted 4.9.170+ #45 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D25528 2113 2104 0x00000000 ffff8801cfc6c740 ffff8801c7a82680 ffff8801db621000 ffff8801c5b18000 ffff8801db621018 ffff8801a85e7b28 ffffffff8280185e 0000000041b58ab3 ffff8801a85e7aa0 00ffffff81bb61ac ffff8801db6218f0 1ffff100350bcf54 Call Trace: [<0000000065833871>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000b68a57f2>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<0000000029813775>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<0000000029813775>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000ae515662>] __lo_release drivers/block/loop.c:1642 [inline] [<00000000ae515662>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 [<000000007958b6e8>] __blkdev_put+0x461/0x840 fs/block_dev.c:1606 [<000000000eef883f>] blkdev_put+0x88/0x560 fs/block_dev.c:1671 [<00000000302f2650>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1678 [<0000000026c8da2e>] __fput+0x274/0x720 fs/file_table.c:208 [<00000000726c81cd>] ____fput+0x16/0x20 fs/file_table.c:244 [<0000000096ac4ad5>] task_work_run+0x108/0x180 kernel/task_work.c:116 [<000000000e8ce102>] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [<000000000e8ce102>] exit_to_usermode_loop+0x13b/0x160 arch/x86/entry/common.c:162 [<0000000059848f45>] prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] [<0000000059848f45>] syscall_return_slowpath arch/x86/entry/common.c:263 [inline] [<0000000059848f45>] do_syscall_64+0x3f7/0x570 arch/x86/entry/common.c:290 [<0000000020cd791e>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Showing all locks held in the system: 2 locks held by khungtaskd/24: #0: (rcu_read_lock){......}, at: [<00000000a50a73a3>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000a50a73a3>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000007532561e>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 2 locks held by getty/2025: #0: (&tty->ldisc_sem){++++++}, at: [<00000000f6b978c4>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000a7679e90>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 3 locks held by syz-executor.4/2113: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000918dc564>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000d0fe19d6>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000ae515662>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000ae515662>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 2 locks held by syz-executor.0/23140: #0: (&tty->ldisc_sem){++++++}, at: [<00000000f6b978c4>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000a7679e90>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.2/5586: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000004705440c>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000fa0ae885>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by blkid/5588: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000c31e061a>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000c240a83a>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/5589: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000c31e061a>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by blkid/5590: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000c31e061a>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000c240a83a>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.170+ #45 ffff8801d98d7cc8 ffffffff81b4fb21 0000000000000001 0000000000000000 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5adbc 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<00000000877a4a5e>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000877a4a5e>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000e1c5ac88>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<000000005be539c2>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000295d2d68>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000eb9793f9>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000eb9793f9>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000eb9793f9>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000eb9793f9>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000007912ed5c>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000bed4f791>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 1897 Comm: rsyslogd Not tainted 4.9.170+ #45 task: 0000000026710977 task.stack: 00000000f87dee34 RIP: 0010:[] c [<00000000a93533cc>] strlen+0x5a/0xa0 lib/string.c:481 RSP: 0018:ffff8801d31777b0 EFLAGS: 00000006 RAX: ffffffff82a5fe63 RBX: dffffc0000000000 RCX: 0000000000000003 RDX: 0000000000000000 RSI: ffffffff830d4620 RDI: ffffffff82a5fe60 RBP: ffff8801d31777c8 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000001 R12: ffffffff82a5fe60 R13: 0000000000000000 R14: ffffffff830c1d40 R15: ffff8801d3177898 FS: 00007f10d0a0d700(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001ea2000 CR3: 00000001d2656000 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffff8801d31777f0c ffff8801d4af9508c 1ffff1003a62ef03c ffff8801d31778c0c ffffffff81200441c ffff8801d3d288f0c ffff8801d3d288a0c ffff8801d3d288f8c ffff8801d3d288a8c ffff8801d3d288b0c ffffffff830d4638c 0000000000000000c Call Trace: [<0000000030f927bf>] trace_event_get_offsets_lock include/trace/events/lock.h:38 [inline] [<0000000030f927bf>] perf_trace_lock+0xe1/0x540 include/trace/events/lock.h:38 [<00000000b76c2087>] trace_lock_release include/trace/events/lock.h:57 [inline] [<00000000b76c2087>] lock_release+0x92a/0xc30 kernel/locking/lockdep.c:3777 [<00000000327d2686>] rcu_lock_release include/linux/rcupdate.h:498 [inline] [<00000000327d2686>] rcu_read_unlock include/linux/rcupdate.h:931 [inline] [<00000000327d2686>] select_task_rq_fair+0x611/0x3920 kernel/sched/fair.c:7262 [<0000000036bba680>] select_task_rq kernel/sched/core.c:1615 [inline] [<0000000036bba680>] try_to_wake_up+0x3e6/0x1030 kernel/sched/core.c:2112 [<000000004c121e60>] wake_up_process kernel/sched/core.c:2197 [inline] [<000000004c121e60>] wake_up_q+0x95/0xf0 kernel/sched/core.c:470 [<000000002b1bef32>] futex_wake_op kernel/futex.c:1596 [inline] [<000000002b1bef32>] do_futex+0x12d3/0x1a70 kernel/futex.c:3287 [<00000000bf2a4618>] SYSC_futex kernel/futex.c:3337 [inline] [<00000000bf2a4618>] SyS_futex+0x253/0x360 kernel/futex.c:3305 [<00000000c75acd71>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<0000000020cd791e>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Code: c75 c4d c41 c80 c3c c24 c00 c74 c3b c48 cbb c00 c00 c00 c00 c00 cfc cff cdf c4c c89 ce0 c48 c83 cc0 c01 c48 c89 cc2 c48 c89 cc1 c48 cc1 cea c03 c83 ce1 c07 c0f cb6 c14 c1a c<38> cca c7f c04 c84 cd2 c75 c23 c80 c38 c00 c75 cde c48 c83 cc4 c08 c4c c29 ce0 c5b c