INFO: task loop0:6981 blocked for more than 120 seconds. Not tainted 4.9.99-gc462abb #23 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. loop0 D27080 6981 2 0x00000000 ffff8801d7ca3000 ffff8801b9338000 ffff8801d6cfd500 ffff8801d870e000 ffff8801db221b98 ffff8801d981edf0 ffffffff839e377d 0000000041b58ab3 ffffffff843c0f58 ffffffff81234380 0000000000000000 ffff8801db222468 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3557 [] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768 [] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180 [] io_schedule include/linux/sched.h:460 [inline] [] bt_get.isra.8+0x27c/0x780 block/blk-mq-tag.c:141 [] __blk_mq_get_tag block/blk-mq-tag.c:163 [inline] [] blk_mq_get_tag+0xac/0x220 block/blk-mq-tag.c:192 [] __blk_mq_alloc_request+0x2a/0xaa0 block/blk-mq.c:196 [] blk_mq_map_request.isra.38+0x3ab/0x900 block/blk-mq.c:1207 [] blk_sq_make_request+0x1d6/0x1220 block/blk-mq.c:1374 [] generic_make_request+0x20e/0x9b0 block/blk-core.c:2055 [] submit_bio+0xb0/0x460 block/blk-core.c:2126 [] dio_bio_submit fs/direct-io.c:420 [inline] [] do_blockdev_direct_IO+0x35da/0x5a80 fs/direct-io.c:1301 [] __blockdev_direct_IO+0xa5/0xd0 fs/direct-io.c:1360 [] blkdev_direct_IO+0xa0/0xd0 fs/block_dev.c:183 [] generic_file_read_iter+0x660/0x1a90 mm/filemap.c:1951 [] blkdev_read_iter+0x105/0x170 fs/block_dev.c:1738 [] lo_rw_aio+0x6b3/0x8a0 drivers/block/loop.c:506 [] do_req_filebacked drivers/block/loop.c:543 [inline] [] loop_handle_cmd drivers/block/loop.c:1698 [inline] [] loop_queue_work+0x3d7/0x2320 drivers/block/loop.c:1710 [] kthread_worker_fn+0x249/0x6b0 kernel/kthread.c:627 [] kthread+0x26d/0x300 kernel/kthread.c:211 [] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Showing all locks held in the system: 2 locks held by khungtaskd/519: #0: (rcu_read_lock){......}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [] watchdog+0x11c/0xa20 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336 2 locks held by getty/3758: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133 1 lock held by syz-executor0/3855: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344 1 lock held by syz-executor6/10945: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344 1 lock held by syz-executor6/10985: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344 1 lock held by syz-executor6/10990: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344 1 lock held by syz-executor6/10993: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344 1 lock held by blkid/11006: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.99-gc462abb #23 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801d85e7d08 ffffffff81eb0f09 0000000000000000 0000000000000001 0000000000000001 0000000000000001 ffffffff810b7da0 ffff8801d85e7d40 ffffffff81ebc207 0000000000000001 0000000000000000 0000000000000003 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99 [] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60 [] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [] check_hung_task kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [] watchdog+0x6b4/0xa20 kernel/hung_task.c:239 [] kthread+0x26d/0x300 kernel/kthread.c:211 [] 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 0xffffffff839f3286