INFO: task syz-executor.1:2115 blocked for more than 140 seconds. Not tainted 4.9.170+ #48 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D25528 2115 1 0x00000004 ffff8801d3cac740 ffff8801cee7ac00 ffff8801db721000 ffff8801d8de2f80 ffff8801db721018 ffff8801a788fa28 ffffffff82801a4e ffffffff82e2bb68 ffffffff81208040 0033602925179ac0 ffff8801db7218f0 1ffff10034f11f34 Call Trace: [<00000000fb9b0fdd>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000a56b1031>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000002c7d35db>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000002c7d35db>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000000f8af29a>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 [<00000000185289d6>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<00000000185289d6>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<00000000936cf0dd>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<00000000dc65d02e>] vfs_ioctl fs/ioctl.c:43 [inline] [<00000000dc65d02e>] file_ioctl fs/ioctl.c:493 [inline] [<00000000dc65d02e>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<0000000017782423>] SYSC_ioctl fs/ioctl.c:694 [inline] [<0000000017782423>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<0000000070bb3d00>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<000000004731c5db>] 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: [<000000004c679ae1>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<000000004c679ae1>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<00000000ca7eccdb>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 2 locks held by getty/2023: #0: (&tty->ldisc_sem){++++++}, at: [<00000000449a61b6>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<000000005adaa63a>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.1/2115: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000000f8af29a>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 1 lock held by syz-executor.2/2116: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e4026432>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.0/2117: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e4026432>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000b8d636b8>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.3/4143: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000001b969f49>] blkdev_put+0x2b/0x560 fs/block_dev.c:1629 3 locks held by syz-executor.4/4150: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000005d40c7ae>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<0000000062d4d74c>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000159683bc>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000159683bc>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 2 locks held by syz-executor.5/4168: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000000f8af29a>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f8695f4a>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by blkid/4160: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e4026432>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by blkid/4163: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e4026432>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000b8d636b8>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/4164: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e4026432>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by blkid/4171: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e4026432>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000b8d636b8>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.4/4177: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e4026432>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.170+ #48 ffff8801d98d7cc8 ffffffff81b4fb21 0000000000000001 0000000000000000 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5adbc 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<000000001f23db21>] __dump_stack lib/dump_stack.c:15 [inline] [<000000001f23db21>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000c6f191bd>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000edd7c740>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<0000000094b4a1ac>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000a83ecc52>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000a83ecc52>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000a83ecc52>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000a83ecc52>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000008b98f1ed>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000253904ed>] 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 skipped: idling at pc 0xffffffff82810ac2