INFO: task syz-executor.5:8185 blocked for more than 140 seconds. Not tainted 4.9.194+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29144 8185 2097 0x80000002 0000000000000083 ffff8801cedc8000 ffff8801c8f47900 ffff8801db721000 ffff88019fd597c0 ffff8801db721018 ffff8801a0f576b8 ffffffff8281af8e ffff8801cedc8000 ffff8801a0f57790 0000000000000046 ffff8801db7218f0 Call Trace: [<00000000ead3efb9>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000b4ed1270>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000009369b568>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000009369b568>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000003dd10230>] lo_release+0x20/0x1b0 drivers/block/loop.c:1663 [<0000000043395d70>] __blkdev_put+0x461/0x840 fs/block_dev.c:1606 [<00000000eacd45e2>] blkdev_put+0x88/0x560 fs/block_dev.c:1671 [<00000000bf514b95>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1678 [<000000001350ca8a>] __fput+0x274/0x720 fs/file_table.c:208 [<00000000379d2210>] ____fput+0x16/0x20 fs/file_table.c:244 [<00000000113ea1a3>] task_work_run+0x108/0x180 kernel/task_work.c:116 [<00000000864349a2>] exit_task_work include/linux/task_work.h:21 [inline] [<00000000864349a2>] do_exit+0x78f/0x2aa0 kernel/exit.c:842 [<00000000dc8d7994>] do_group_exit+0x111/0x300 kernel/exit.c:946 [<00000000524ba93a>] get_signal+0x377/0x1cb0 kernel/signal.c:2395 [<0000000007874264>] do_signal+0x9c/0x1920 arch/x86/kernel/signal.c:812 [<00000000abe667f0>] exit_to_usermode_loop+0x11c/0x160 arch/x86/entry/common.c:159 [<000000000626a69d>] prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] [<000000000626a69d>] syscall_return_slowpath arch/x86/entry/common.c:266 [inline] [<000000000626a69d>] do_syscall_64+0x3ab/0x5c0 arch/x86/entry/common.c:293 [<00000000d4ae23ea>] 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: [<000000004a2cd4c2>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<000000004a2cd4c2>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000005120eb84>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 2 locks held by getty/2028: #0: (&tty->ldisc_sem){++++++}, at: [<00000000abe8c6ee>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.+.}, at: [<0000000090d29ad2>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.5/8185: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003eba0848>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<000000003dd10230>] lo_release+0x20/0x1b0 drivers/block/loop.c:1663 1 lock held by syz-executor.5/8387: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000067de4d26>] blkdev_put+0x2b/0x560 fs/block_dev.c:1629 2 locks held by syz-executor.5/8748: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003eba0848>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<000000003dd10230>] lo_release+0x20/0x1b0 drivers/block/loop.c:1663 2 locks held by syz-executor.3/17511: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000b6b27375>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000adffec09>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.0/17672: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000c37817c8>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000006ccffc40>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by syz-executor.0/17723: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000b6b27375>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by syz-executor.4/17676: #0: (loop_index_mutex){+.+.+.}, at: [<000000007da8a6d2>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.4/17695: #0: (loop_index_mutex){+.+.+.}, at: [<000000007da8a6d2>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.4/17705: #0: (loop_index_mutex){+.+.+.}, at: [<000000007da8a6d2>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.4/17722: #0: (loop_index_mutex){+.+.+.}, at: [<000000007da8a6d2>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 2 locks held by syz-executor.5/17671: #0: (loop_index_mutex){+.+.+.}, at: [<000000007da8a6d2>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<00000000e0f59c0c>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1987 1 lock held by syz-executor.5/17690: #0: (loop_index_mutex){+.+.+.}, at: [<000000007da8a6d2>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.5/17703: #0: (loop_index_mutex){+.+.+.}, at: [<000000007da8a6d2>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.5/17721: #0: (loop_index_mutex){+.+.+.}, at: [<000000007da8a6d2>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 2 locks held by blkid/17681: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000b6b27375>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000adffec09>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.194+ #0 ffff8801d98d7cc8 ffffffff81b67001 0000000000000000 0000000000000000 0000000000000000 ffffffff81099d01 dffffc0000000000 ffff8801d98d7d00 ffffffff81b7229c 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<000000007d3eb629>] __dump_stack lib/dump_stack.c:15 [inline] [<000000007d3eb629>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000f2ef4162>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<000000009cc1a074>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000bbaa2ba3>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000006fb8ca18>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000006fb8ca18>] check_hung_task kernel/hung_task.c:126 [inline] [<000000006fb8ca18>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<000000006fb8ca18>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<00000000a5b9ea80>] kthread+0x278/0x310 kernel/kthread.c:211 [<000000003a6e2e78>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff8282a0e1