INFO: task syz-executor.0:30053 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.0 D25400 30053 25756 0x00000004 0000000000000083 ffff8801a38a0000 ffff8801a1eef380 ffff8801db721000 ffff8801c9114740 ffff8801db721018 ffff8801a81f7988 ffffffff8281af8e ffffffff830c3120 ffff8801a81f79a8 00ff8801a81f78d8 ffff8801db7218f0 Call Trace: [<0000000076c1e196>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<000000001abf8336>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000008667722a>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000008667722a>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<0000000049302392>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 [<0000000057a229ac>] loop_reread_partitions+0x7c/0x90 drivers/block/loop.c:637 [<00000000c60bbcab>] loop_clr_fd+0x7dd/0xa60 drivers/block/loop.c:1081 [<000000000c9c315e>] lo_ioctl+0x7e9/0x1b10 drivers/block/loop.c:1414 [<00000000f97cc904>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<00000000f97cc904>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<00000000324cd8a0>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<00000000aad7f3e0>] vfs_ioctl fs/ioctl.c:43 [inline] [<00000000aad7f3e0>] file_ioctl fs/ioctl.c:493 [inline] [<00000000aad7f3e0>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<00000000b087dec3>] SYSC_ioctl fs/ioctl.c:694 [inline] [<00000000b087dec3>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<000000002b73c888>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<000000005b2518ea>] 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: [<000000009412d64d>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<000000009412d64d>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.?..}, at: [<00000000cbfea5d9>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 1 lock held by rsyslogd/1895: #0: (&f->f_pos_lock){+.+.+.}, at: [<0000000095f2a35e>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2023: #0: (&tty->ldisc_sem){++++++}, at: [<00000000c60683a6>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.+.}, at: [<00000000a6801c3f>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.5/15558: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000046aa0697>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000073040ed3>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 1 lock held by syz-executor.3/25750: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000046aa0697>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.0/30053: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000d2e883f8>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<0000000049302392>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by syz-executor.0/30063: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000046aa0697>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.1/30064: #0: (loop_index_mutex){+.+.+.}, at: [<000000002ce587af>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<0000000038459306>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1987 2 locks held by blkid/30066: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000046aa0697>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000073040ed3>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/30069: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000046aa0697>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000073040ed3>] 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 ffff8801d98efcc8 ffffffff81b67001 0000000000000001 0000000000000000 0000000000000001 ffffffff81099d01 dffffc0000000000 ffff8801d98efd00 ffffffff81b7229c 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<00000000fa20c19c>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000fa20c19c>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000decffe3c>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<0000000042944176>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000de002e5f>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000046b0b86>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000046b0b86>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000046b0b86>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000046b0b86>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000004dcac926>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000b9714d15>] 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