INFO: task syz-executor.5:2087 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.5 D25168 2087 1 0x00000004 0000000000000083 ffff8801d1845f00 ffff8801d0119b80 ffff8801db621000 ffff8801d21fdf00 ffff8801db621018 ffff8801a9367688 ffffffff8281af8e 0000000041b58ab3 ffffffff82e2c730 00ffffff81204ef0 ffff8801db6218f0 Call Trace: [<00000000869b8258>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000b67c773e>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000329d39be>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000329d39be>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000006239f5f8>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 [<00000000c27fe4de>] __blkdev_get+0x268/0xeb0 fs/block_dev.c:1287 [<00000000fe765c4c>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<000000004c3e4f7b>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<0000000090de5620>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<00000000bfe9aecf>] vfs_open+0x105/0x230 fs/open.c:904 [<00000000da530fb0>] do_last fs/namei.c:3541 [inline] [<00000000da530fb0>] path_openat+0xbf5/0x2f60 fs/namei.c:3665 [<00000000dd009421>] do_filp_open+0x1a1/0x280 fs/namei.c:3699 [<0000000013cd9a06>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<00000000d3df840b>] SYSC_open fs/open.c:1115 [inline] [<00000000d3df840b>] SyS_open+0x2d/0x40 fs/open.c:1110 [<0000000012604b3d>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<000000003a874204>] 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: [<00000000875fe528>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000875fe528>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000005d36ec58>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 1 lock held by rsyslogd/1895: #0: (&f->f_pos_lock){+.+.+.}, at: [<000000006c2df590>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2022: #0: (&tty->ldisc_sem){++++++}, at: [<0000000093c9da61>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+...}, at: [<000000007d823b9c>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.5/2087: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000550a7b35>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000006239f5f8>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.4/4665: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000550a7b35>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000006239f5f8>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.2/5307: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000550a7b35>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000006239f5f8>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.3/5326: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000550a7b35>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000006239f5f8>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.1/6099: #0: (loop_index_mutex){+.+.+.}, at: [<000000000e5ff6de>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 #1: (&lo->lo_ctl_mutex#2){+.+...}, at: [<000000009d033535>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1987 2 locks held by syz-executor.0/6104: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000aa85eee8>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000006cf4ca71>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by blkid/6112: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000550a7b35>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000006239f5f8>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.194+ #0 ffff8801d98efcc8 ffffffff81b67001 0000000000000000 0000000000000000 0000000000000000 ffffffff81099d01 dffffc0000000000 ffff8801d98efd00 ffffffff81b7229c 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<0000000049bcfe1d>] __dump_stack lib/dump_stack.c:15 [inline] [<0000000049bcfe1d>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000b619252f>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000b1a1e17a>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000632d44d4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<0000000035360cee>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<0000000035360cee>] check_hung_task kernel/hung_task.c:126 [inline] [<0000000035360cee>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<0000000035360cee>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<00000000445e62b3>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000921ab10a>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff8282a0e1