INFO: task syz-executor.5:2108 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 D25416 2108 1 0x00000004 0000000000000083 ffff8801cf8f2f80 ffff8801d271f380 ffff8801db721000 ffff8801d2290000 ffff8801db721018 ffff8801a5417688 ffffffff8281af8e ffff8801cf8f2f80 ffffffff841f8b40 00ff8801a54175e8 ffff8801db7218f0 Call Trace: [<000000003355d995>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<0000000066425d45>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<0000000027d011c3>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<0000000027d011c3>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000c2972bd5>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 [<0000000031c7e522>] __blkdev_get+0x268/0xeb0 fs/block_dev.c:1287 [<0000000047acb009>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<00000000b2825ec5>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<000000002477cf8c>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<0000000037daced6>] vfs_open+0x105/0x230 fs/open.c:904 [<00000000da23e4f0>] do_last fs/namei.c:3541 [inline] [<00000000da23e4f0>] path_openat+0xbf5/0x2f60 fs/namei.c:3665 [<00000000160f97bd>] do_filp_open+0x1a1/0x280 fs/namei.c:3699 [<000000005f7ac8b2>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<0000000064c02ecb>] SYSC_open fs/open.c:1115 [inline] [<0000000064c02ecb>] SyS_open+0x2d/0x40 fs/open.c:1110 [<00000000a354420a>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000068bd169>] 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: [<00000000299cf6d2>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000299cf6d2>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<0000000053d29fa4>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 2 locks held by getty/2027: #0: (&tty->ldisc_sem){++++++}, at: [<000000006fd26b34>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+...}, at: [<0000000055f5fffb>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.5/2108: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000080f9cf81>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000c2972bd5>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.3/2114: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000080f9cf81>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000c2972bd5>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.1/2118: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000080f9cf81>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000c2972bd5>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.4/2120: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000080f9cf81>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000c2972bd5>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.0/3049: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<000000001f0e6e77>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000b670551c>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by syz-executor.2/3068: #0: (loop_index_mutex){+.+.+.}, at: [<0000000001df6dd1>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<000000009d23131e>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1987 1 lock held by syz-executor.2/3075: #0: (loop_index_mutex){+.+.+.}, at: [<0000000001df6dd1>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.2/3084: #0: (loop_index_mutex){+.+.+.}, at: [<0000000001df6dd1>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 2 locks held by blkid/3074: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000080f9cf81>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000c2972bd5>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.194+ #0 ffff8801d98d7cc8 ffffffff81b67001 0000000000000001 0000000000000000 0000000000000001 ffffffff81099d01 dffffc0000000000 ffff8801d98d7d00 ffffffff81b7229c 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<00000000a1e50ddd>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000a1e50ddd>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<000000008ae8751a>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000bb9cc025>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000e9316d49>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000cf0e9207>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000cf0e9207>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000cf0e9207>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000cf0e9207>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000007783522f>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000c8baf74b>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff8282a0e1