INFO: task syz-executor.0:13346 blocked for more than 140 seconds. Not tainted 4.9.202+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D26808 13346 11717 0x00000004 0000000000000087 ffff8801d48b97c0 0000000000000000 ffff8801db71ffc0 ffff8801da6b2f80 ffff8801db71ffd8 ffff8801b1d877c8 ffffffff8280a1de dffffc0000000000 ffff8801d48b97c0 00ff8801b1d87718 ffff8801db7208b0 Call Trace: [<000000005985ce48>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<0000000071193c57>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000ba3e4109>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000ba3e4109>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000ef651d12>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 [<000000006a122aa7>] loop_reread_partitions+0x7c/0x90 drivers/block/loop.c:637 [<00000000b37c1c25>] loop_set_status+0xc02/0x1260 drivers/block/loop.c:1196 [<0000000085f6cd81>] loop_set_status64+0xd7/0x130 drivers/block/loop.c:1305 [<000000002309aaa1>] lo_ioctl+0x4c7/0x1b10 drivers/block/loop.c:1430 [<000000009c52142d>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<000000009c52142d>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<000000000433b7e6>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<000000001157372f>] vfs_ioctl fs/ioctl.c:43 [inline] [<000000001157372f>] file_ioctl fs/ioctl.c:493 [inline] [<000000001157372f>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<000000009b57119e>] SYSC_ioctl fs/ioctl.c:694 [inline] [<000000009b57119e>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<00000000f0e93911>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<000000003f4bbf50>] 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: [<00000000d4215e69>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000d4215e69>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<00000000878c8693>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1891: #0: (&f->f_pos_lock){+.+.+.}, at: [<0000000055a69ef0>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2018: #0: (&tty->ldisc_sem){++++++}, at: [<0000000030edce29>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+...}, at: [<000000001c97eb89>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.0/13346: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000f4e518ff>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ef651d12>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by syz-executor.2/13352: #0: (loop_index_mutex){+.+.+.}, at: [<00000000dc89f32f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<0000000093b2d06e>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1988 2 locks held by blkid/13354: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000009df19fec>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000b09c79f6>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.3/13360: #0: (loop_index_mutex){+.+.+.}, at: [<00000000dc89f32f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.3/13368: #0: (loop_index_mutex){+.+.+.}, at: [<00000000dc89f32f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.3/13373: #0: (loop_index_mutex){+.+.+.}, at: [<00000000dc89f32f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.3/13377: #0: (loop_index_mutex){+.+.+.}, at: [<00000000dc89f32f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.3/13381: #0: (loop_index_mutex){+.+.+.}, at: [<00000000dc89f32f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.3/13396: #0: (loop_index_mutex){+.+.+.}, at: [<00000000dc89f32f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.4/13372: #0: (loop_index_mutex){+.+.+.}, at: [<00000000dc89f32f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.4/13376: #0: (loop_index_mutex){+.+.+.}, at: [<00000000dc89f32f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.202+ #0 ffff8801d98d7cc8 ffffffff81b55d2b 0000000000000001 0000000000000000 0000000000000001 ffffffff8109a001 dffffc0000000000 ffff8801d98d7d00 ffffffff81b60fcc 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<0000000078c175c5>] __dump_stack lib/dump_stack.c:15 [inline] [<0000000078c175c5>] dump_stack+0xcb/0x130 lib/dump_stack.c:56 [<0000000022e9b820>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000b13fb515>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<000000004201de84>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000008fb4f500>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000008fb4f500>] check_hung_task kernel/hung_task.c:126 [inline] [<000000008fb4f500>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<000000008fb4f500>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000005677b6d9>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000bf2693f9>] 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 0xffffffff82819331