INFO: task syz-executor.4:2136 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.4 D25016 2136 1 0x00000004 0000000000000083 ffff8801d6675f00 ffff8801d09ff380 ffff8801db71ffc0 ffff8801d1ab5f00 ffff8801db71ffd8 ffff8801a10df688 ffffffff8280a1de ffff8801d6675f00 ffffffff841f6b00 00ff8801a10df5e8 ffff8801db7208b0 Call Trace: [<0000000027243641>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<0000000075d87a6b>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000dd00d4e8>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000dd00d4e8>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000ff9cacd0>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 [<00000000279f8fea>] __blkdev_get+0x268/0xeb0 fs/block_dev.c:1287 [<00000000ac9998ed>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<0000000041f5e31c>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<000000002dd0d562>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<000000004d1a8322>] vfs_open+0x105/0x230 fs/open.c:904 [<000000004d4c3958>] do_last fs/namei.c:3457 [inline] [<000000004d4c3958>] path_openat+0xbf5/0x2f60 fs/namei.c:3581 [<0000000056c9e24f>] do_filp_open+0x1a1/0x280 fs/namei.c:3615 [<00000000d21df944>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<000000003915c1a1>] SYSC_open fs/open.c:1115 [inline] [<000000003915c1a1>] SyS_open+0x2d/0x40 fs/open.c:1110 [<0000000084c3c4dc>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000958d0901>] 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: [<00000000412b00c9>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000412b00c9>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000004f52051c>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1897: #0: (&f->f_pos_lock){+.+.+.}, at: [<000000008ed82299>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2024: #0: (&tty->ldisc_sem){++++++}, at: [<000000008a8981fc>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+...}, at: [<0000000087f6f8f8>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.4/2136: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f2bed40d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ff9cacd0>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.3/4722: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f2bed40d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ff9cacd0>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.5/5490: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f2bed40d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ff9cacd0>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.2/5506: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f2bed40d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ff9cacd0>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.0/6460: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<0000000015f531d8>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000004c871b1a>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by syz-executor.0/6463: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f2bed40d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.1/6467: #0: (loop_index_mutex){+.+.+.}, at: [<00000000725981ed>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<000000000984ef59>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1988 1 lock held by syz-executor.1/6489: #0: (loop_index_mutex){+.+.+.}, at: [<00000000725981ed>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 2 locks held by blkid/6471: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f2bed40d>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ff9cacd0>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 ============================================= 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: [<000000005cc4e218>] __dump_stack lib/dump_stack.c:15 [inline] [<000000005cc4e218>] dump_stack+0xcb/0x130 lib/dump_stack.c:56 [<000000002068b8ef>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000e01a5fb5>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000357ad0d4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<0000000030daa572>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<0000000030daa572>] check_hung_task kernel/hung_task.c:126 [inline] [<0000000030daa572>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<0000000030daa572>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000007635f59e>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000bd1aa399>] 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