INFO: task syz-executor.2:2116 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.2 D24648 2116 1 0x00000004 ffff8801d0660000 ffff8801a127c780 ffff8801db721000 ffff8801a107df00 ffff8801db721018 ffff8801b0937a28 ffffffff8280185e ffffffff82e2bb28 ffffffff81208040 007aac8eee5a2002 ffff8801db7218f0 1ffff10036126f34 Call Trace: [<00000000a531d594>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<000000000d6f271f>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000003325f9e3>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000003325f9e3>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000c01d10f3>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 [<00000000736d887f>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<00000000736d887f>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<000000005f7132f2>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<000000009d62898f>] vfs_ioctl fs/ioctl.c:43 [inline] [<000000009d62898f>] file_ioctl fs/ioctl.c:493 [inline] [<000000009d62898f>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<00000000c95514fc>] SYSC_ioctl fs/ioctl.c:694 [inline] [<00000000c95514fc>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<00000000853d1e73>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<00000000b9b90ca9>] 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: [<0000000020a9dae9>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<0000000020a9dae9>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<00000000f44965d6>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1903: #0: (&f->f_pos_lock){+.+.+.}, at: [<0000000009712a37>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2030: #0: (&tty->ldisc_sem){++++++}, at: [<00000000c84876b2>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<000000003f3f642e>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.2/2116: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000c01d10f3>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 2 locks held by syz-executor.3/2122: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ac1ba47c>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000133660db>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.1/2137: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ac1ba47c>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000133660db>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.0/2139: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ac1ba47c>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.5/5938: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ac1ba47c>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000133660db>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.4/6265: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000c01d10f3>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000004386d45d>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 3 locks held by blkid/6260: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000fa8b93ca>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<000000005cba28b3>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000c9c68e60>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000c9c68e60>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 1 lock held by blkid/6266: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000c01d10f3>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 1 lock held by blkid/6268: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000c01d10f3>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 2 locks held by blkid/6273: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ac1ba47c>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000133660db>] 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: [<00000000fd56a571>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000fd56a571>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<000000007b2cfa7f>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<0000000083e267ee>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<000000008eacee51>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000005ee32812>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000005ee32812>] check_hung_task kernel/hung_task.c:126 [inline] [<000000005ee32812>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<000000005ee32812>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000004498922f>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000f0d72941>] 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