INFO: task syz-executor.0:13452 blocked for more than 140 seconds. Not tainted 4.9.180+ #3 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D28648 13452 2097 0x00000004 0000000000000087 ffff8801d4362f80 ffff8801a20dee00 ffff8801db621000 ffff8801cc042f80 ffff8801db621018 ffff8801d15277c8 ffffffff8280932e ffffffff830c2ee0 ffff8801d15277e8 00ff8801d1527718 ffff8801db6218f0 Call Trace: [<000000008872f0c8>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000d877f9a0>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<0000000045cb605d>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<0000000045cb605d>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000778193a5>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 [<000000005ca0f48c>] loop_reread_partitions+0x7c/0x90 drivers/block/loop.c:637 [<00000000d2681f79>] loop_set_status+0xc02/0x1260 drivers/block/loop.c:1196 [<000000003e1f3eec>] loop_set_status64+0xd7/0x130 drivers/block/loop.c:1305 [<00000000acc4e012>] lo_ioctl+0x4c7/0x1b10 drivers/block/loop.c:1430 [<00000000f1be6715>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<00000000f1be6715>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<0000000087394517>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<00000000d27d5893>] vfs_ioctl fs/ioctl.c:43 [inline] [<00000000d27d5893>] file_ioctl fs/ioctl.c:493 [inline] [<00000000d27d5893>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<000000004329d6d2>] SYSC_ioctl fs/ioctl.c:694 [inline] [<000000004329d6d2>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<00000000ac812ea5>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000dd1297ef>] 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: [<0000000099ed2ec7>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<0000000099ed2ec7>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.?..}, at: [<00000000720bf086>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 1 lock held by rsyslogd/1886: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000f41ba062>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2015: #0: (&tty->ldisc_sem){++++++}, at: [<00000000e0964a6a>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000b102ec80>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.0/13452: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000861b8586>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000778193a5>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by syz-executor.0/13490: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000861b8586>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 2 locks held by syz-executor.5/13492: #0: (loop_index_mutex){+.+.+.}, at: [<00000000198bd8b3>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<00000000bece2942>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1987 1 lock held by syz-executor.4/13493: #0: (loop_index_mutex){+.+.+.}, at: [<00000000198bd8b3>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.4/13505: #0: (loop_index_mutex){+.+.+.}, at: [<00000000198bd8b3>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by blkid/13494: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003d2fc492>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.3/13496: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003d2fc492>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000eb844ea1>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.180+ #3 ffff8801d98d7cc8 ffffffff81b577f1 0000000000000001 0000000000000000 0000000000000001 ffffffff81099901 dffffc0000000000 ffff8801d98d7d00 ffffffff81b62a8c 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<00000000270de5d5>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000270de5d5>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000d6a447fb>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<0000000030e74e83>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<0000000097d2e768>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000c092618d>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000c092618d>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000c092618d>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000c092618d>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<00000000218a6e68>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000a429d829>] 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 0xffffffff82818481