INFO: task syz-executor.2:2120 blocked for more than 140 seconds. Not tainted 4.9.170+ #48 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D25528 2120 1 0x00000004 ffff8801cf532f80 ffff8801d3d96880 ffff8801db621000 ffff8801d3a797c0 ffff8801db621018 ffff8801c64bf988 ffffffff82801a4e 0000000000000000 ffffffff830c1d40 00ff8801c64bf9b0 ffff8801db6218f0 1ffff10038c97f20 Call Trace: [<0000000015b1d051>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000bc72a1b4>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<0000000064ac9d50>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<0000000064ac9d50>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<0000000038f8c6aa>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 [<00000000fcc44f9a>] loop_reread_partitions+0x7c/0x90 drivers/block/loop.c:638 [<00000000384fac38>] loop_clr_fd+0x7dd/0xa60 drivers/block/loop.c:1082 [<000000004cf27881>] lo_ioctl+0x7b6/0x1a10 drivers/block/loop.c:1415 [<00000000daa67189>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<00000000daa67189>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<00000000ea3b8c7f>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<000000006d26ff88>] vfs_ioctl fs/ioctl.c:43 [inline] [<000000006d26ff88>] file_ioctl fs/ioctl.c:493 [inline] [<000000006d26ff88>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<0000000078812595>] SYSC_ioctl fs/ioctl.c:694 [inline] [<0000000078812595>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<00000000813ba8ff>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<00000000de7c5ca2>] 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: [<00000000e671be2c>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000e671be2c>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000005117b02d>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1904: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000b4c916dc>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2032: #0: (&tty->ldisc_sem){++++++}, at: [<00000000a15314fb>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000dbd8d484>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.2/2120: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000003b75e333>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<0000000038f8c6aa>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by syz-executor.1/2121: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004a9ad273>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000013e9172e>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.3/2124: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004a9ad273>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000013e9172e>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 3 locks held by syz-executor.5/2132: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000072e63140>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000870ddc5b>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000c8776139>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000c8776139>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 2 locks held by syz-executor.4/2133: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004a9ad273>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000013e9172e>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/6492: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000003b75e333>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 2 locks held by blkid/6497: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004a9ad273>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000013e9172e>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.170+ #48 ffff8801d98d7cc8 ffffffff81b4fb21 0000000000000001 0000000000000000 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5adbc 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<0000000049f8f043>] __dump_stack lib/dump_stack.c:15 [inline] [<0000000049f8f043>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<000000006356024e>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000e3d05b6a>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000ccac3ee6>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000008653a3b0>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000008653a3b0>] check_hung_task kernel/hung_task.c:126 [inline] [<000000008653a3b0>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<000000008653a3b0>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<00000000084fb62c>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000ea71e5f0>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff82810ac2