INFO: task syz-executor.5:2106 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 2106 1 0x00000004 ffff8801cfe75f00 ffff8801d43cee00 ffff8801db621000 ffff8801d436af80 ffff8801db621018 ffff8801a85d7a28 ffffffff8280185e ffffffff82e2bb28 ffffffff81208040 002cf7e3bcade95b ffff8801db6218f0 1ffff100350baf34 Call Trace: [<000000009065f256>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<000000005ca489ee>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000006ebf4322>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000006ebf4322>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000007d1647e1>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 [<00000000cfc54c5b>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<00000000cfc54c5b>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<00000000a767bad3>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<00000000b63d67e4>] vfs_ioctl fs/ioctl.c:43 [inline] [<00000000b63d67e4>] file_ioctl fs/ioctl.c:493 [inline] [<00000000b63d67e4>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<000000004fb0ac70>] SYSC_ioctl fs/ioctl.c:694 [inline] [<000000004fb0ac70>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<00000000a030170c>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<000000009fbc6928>] 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: [<000000009408e799>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<000000009408e799>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<00000000462b7cba>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 2 locks held by getty/2019: #0: (&tty->ldisc_sem){++++++}, at: [<00000000ddf164a2>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<0000000042cec63e>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.5/2106: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000007d1647e1>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 2 locks held by syz-executor.0/2107: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033c48840>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000cd5ba9a0>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.2/2109: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033c48840>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.3/2114: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033c48840>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000cd5ba9a0>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.4/2117: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033c48840>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.1/10802: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000007d1647e1>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000d7b88dd0>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 3 locks held by blkid/10798: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ec904421>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000af334dae>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000ca103c41>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000ca103c41>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 2 locks held by blkid/10807: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033c48840>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000cd5ba9a0>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by blkid/10808: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033c48840>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000cd5ba9a0>] 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 0000000000000000 Call Trace: [<00000000084f260c>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000084f260c>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000cedf5e11>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000d5887f1a>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000777b9da5>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000c8e5eea4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000c8e5eea4>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000c8e5eea4>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000c8e5eea4>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000009f9e9d3e>] kthread+0x278/0x310 kernel/kthread.c:211 [<000000001e275a0b>] 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 skipped: idling at pc 0xffffffff828108d2