INFO: task syz-executor.5:2132 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.5 D25528 2132 1 0x00000004 ffff8801d9925f00 0000000000000000 ffff8801db621000 ffffffff83031180 ffff8801db621018 ffff8801a8effb28 ffffffff8280185e ffff8801d9925f00 ffff8801a8effc00 0000000000000046 ffff8801db6218f0 1ffff100351dff54Call Trace: [<000000009f048b25>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000e69456cb>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<0000000069b6a662>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<0000000069b6a662>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000005c31f91a>] __lo_release drivers/block/loop.c:1642 [inline] [<000000005c31f91a>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 [<00000000e6c4bcf5>] __blkdev_put+0x461/0x840 fs/block_dev.c:1606 [<000000005a4c636f>] blkdev_put+0x88/0x560 fs/block_dev.c:1671 [<000000008ba8cb47>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1678 [<00000000f2513945>] __fput+0x274/0x720 fs/file_table.c:208 [<000000001e8a375c>] ____fput+0x16/0x20 fs/file_table.c:244 [<000000006a52b905>] task_work_run+0x108/0x180 kernel/task_work.c:116 [<000000006db38472>] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [<000000006db38472>] exit_to_usermode_loop+0x13b/0x160 arch/x86/entry/common.c:162 [<00000000885b6b57>] prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] [<00000000885b6b57>] syscall_return_slowpath arch/x86/entry/common.c:263 [inline] [<00000000885b6b57>] do_syscall_64+0x3f7/0x570 arch/x86/entry/common.c:290 [<00000000a09709a8>] 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: [<0000000092bcc83f>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] (rcu_read_lock){......}, at: [<0000000092bcc83f>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 (tasklist_lock){.+.+..}, at: [<00000000e6f361ef>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 #0: (&f->f_pos_lock){+.+.+.}, at: [<000000009d1dde3a>] __fdget_pos+0xa8/0xd0 fs/file.c:782 #0: (&tty->ldisc_sem){++++++}, at: [<00000000fa58ffef>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 (&ldata->atomic_read_lock){+.+.+.}, at: [<000000004142480a>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000008fffed06>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 (loop_index_mutex){+.+.+.}, at: [<00000000bba19ffe>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 (loop_ctl_mutex#2){+.+.+.}, at: [<000000005c31f91a>] __lo_release drivers/block/loop.c:1642 [inline] (loop_ctl_mutex#2){+.+.+.}, at: [<000000005c31f91a>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e2a44874>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 (loop_index_mutex){+.+.+.}, at: [<00000000b2f4cf91>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e2a44874>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 (loop_index_mutex){+.+.+.}, at: [<00000000b2f4cf91>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e2a44874>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 (loop_index_mutex){+.+.+.}, at: [<00000000b2f4cf91>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 #0: (loop_ctl_mutex/1){+.+.+.}, at: [<0000000076b5553c>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 (&bdev->bd_mutex){+.+.+.}, at: [<000000004c79f950>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e2a44874>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 (loop_index_mutex){+.+.+.}, at: [<00000000b2f4cf91>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.170+ #45 ffff8801d98d7cc8 ffffffff81b4fb21 0000000000000000 0000000000000000 0000000000000000 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5adbc 0000000000000000 0000000000000000 0000000000000000Call Trace: [<00000000c94b8dc7>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000c94b8dc7>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<000000000341777c>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000da20b2ab>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<0000000013b0cdf2>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000dea10b01>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000dea10b01>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000dea10b01>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000dea10b01>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<00000000e0b0a7dd>] kthread+0x278/0x310 kernel/kthread.c:211 [<000000007720b2bf>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 1912 Comm: rs:main Q:Reg Not tainted 4.9.170+ #45 task: 00000000a0d31a07 task.stack: 00000000264bce10 RIP: 0033:[<00007f7963782624>] c [<00000000ab8e86ab>] 0x7f7963782624 RSP: 002b:00007f79623a74a8 EFLAGS: 00000293 RAX: 0000000000d9aa60 RBX: 0000000000db4e28 RCX: 0000000000d8bc70 RDX: 0000000000000009 RSI: 0000000000db4e8d RDI: 0000000000d9aa60 RBP: 0000000000000009 R08: 0000000000000000 R09: fffffffffffcd800 R10: 00007f79623a7650 R11: 00007f79637b6a50 R12: 0000000000000058 R13: 0000000000db4ed0 R14: 0000000000000009 R15: 0000000000d8bc50 FS: 00007f79623a8700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6e291e5a30 CR3: 00000001d489c000 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400