INFO: task loop0:5256 blocked for more than 120 seconds. Not tainted 4.4.120-gd63fdf6 #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. loop0 D ffff8800aaf6ede0 26888 5256 2 0x00000000 ffff8800aaf6ede0 ffffffff83fb2270 ffffffff81237410 0000000000000000 0000000000000000 0000000000000000 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8 ffffffff84217840 ffff8801cf108000 ffff8800aaf6f670 Call Trace: [] schedule+0x7a/0x1b0 kernel/sched/core.c:3353 [] schedule_timeout+0x3a0/0x970 kernel/time/timer.c:1515 [] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:4935 [] io_schedule include/linux/sched.h:447 [inline] [] bt_get+0x305/0x760 block/blk-mq-tag.c:301 [] __blk_mq_get_tag block/blk-mq-tag.c:325 [inline] [] blk_mq_get_tag+0x1eb/0x340 block/blk-mq-tag.c:353 [] __blk_mq_alloc_request+0x24/0xa50 block/blk-mq.c:215 [] blk_mq_map_request+0x8d1/0xde0 block/blk-mq.c:1190 [] blk_sq_make_request+0x1a0/0xfc0 block/blk-mq.c:1361 [] generic_make_request+0x311/0x990 block/blk-core.c:2081 [] submit_bio+0x17a/0x540 block/blk-core.c:2154 [] dio_bio_submit fs/direct-io.c:409 [inline] [] do_blockdev_direct_IO+0x6ba8/0x8810 fs/direct-io.c:1283 [] __blockdev_direct_IO+0xae/0xe0 fs/direct-io.c:1342 [] blkdev_direct_IO+0xb2/0xe0 fs/block_dev.c:167 [] generic_file_read_iter+0x360/0x1160 mm/filemap.c:1791 [] blkdev_read_iter+0x105/0x170 fs/block_dev.c:1679 [] lo_rw_aio drivers/block/loop.c:506 [inline] [] lo_rw_simple drivers/block/loop.c:520 [inline] [] do_req_filebacked drivers/block/loop.c:558 [inline] [] loop_handle_cmd drivers/block/loop.c:1698 [inline] [] loop_queue_work+0x1eac/0x31c0 drivers/block/loop.c:1710 [] kthread_worker_fn+0x27b/0x600 kernel/kthread.c:602 [] kthread+0x268/0x300 kernel/kthread.c:211 [] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:506 no locks held by loop0/5256. Sending NMI to all CPUs: NMI backtrace for cpu 0 CPU: 0 PID: 485 Comm: khungtaskd Not tainted 4.4.120-gd63fdf6 #28 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8800bb31c800 task.stack: ffff8800bacb8000 RIP: 0010:[] [] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline] RIP: 0010:[] [] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline] RIP: 0010:[] [] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline] RIP: 0010:[] [] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69 RSP: 0018:ffff8800bacbfcb8 EFLAGS: 00000046 RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000 RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300 RBP: ffff8800bacbfce0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246 R13: 0000000000000003 R14: ffffffff8426f420 R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5e836a59b8 CR3: 00000001d34ba000 CR4: 0000000000160670 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffffffff8426f420 ffffffff847efb00 fffffbfff08fda14 dffffc0000000000 ffff8801db31bca0 ffff8800bacbfd00 ffffffff810b999b ffffffff839f63c0 0000000000000003 ffff8800bacbfd60 ffffffff81d0eff4 0000000000000000 Call Trace: [] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33 [] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85 [] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 [] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline] [] check_hung_task kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [] watchdog+0x6fa/0xae0 kernel/hung_task.c:238 [] kthread+0x268/0x300 kernel/kthread.c:211 [] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:506 Code: b3 5f ff f6 c4 10 75 e1 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 74 1a e8 6b 2f 17 00 4c 89 e7 57 9d 0f 1f NMI backtrace for cpu 1 CPU: 1 PID: 7635 Comm: syz-executor5 Not tainted 4.4.120-gd63fdf6 #28 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8800b67d6000 task.stack: ffff8800b6718000 RIP: 0010:[] [] loop_set_fd drivers/block/loop.c:897 [inline] RIP: 0010:[] [] lo_ioctl+0x4e6/0x19c0 drivers/block/loop.c:1351 RSP: 0018:ffff8800b671fb98 EFLAGS: 00000246 RAX: 1ffff10017391d8d RBX: dffffc0000000000 RCX: ffffffff8241f983 RDX: 0000000000010000 RSI: ffffc900046f7000 RDI: ffff8800b9c8ec68 RBP: ffff8800b671fc18 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000000 R11: 1ffff10016ce3f2e R12: ffff8800b9c8e920 R13: ffff8800b8c7f600 R14: 0000000000000000 R15: ffff8800b9c8dc00 FS: 00007f2fa9771700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fdb41b08000 CR3: 00000001d6080000 CR4: 0000000000160670 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: ffff8800b671fbe0 1ffff10016ce3f78 0000000b00006000 ffff8800b8c7f750 0000002900700000 ffff8800b9c8eb00 ffff8800b9c8e920 ffff8801d613d600 ffff8800b9c8dcf0 000000000002001d ffff8800b8c7f758 ffff8800b9c8dc00 Call Trace: [] __blkdev_driver_ioctl block/ioctl.c:288 [inline] [] blkdev_ioctl+0x4ab/0x1990 block/ioctl.c:584 [] block_ioctl+0xde/0x120 fs/block_dev.c:1625 [] vfs_ioctl fs/ioctl.c:43 [inline] [] do_vfs_ioctl+0x7aa/0xee0 fs/ioctl.c:607 [] SYSC_ioctl fs/ioctl.c:622 [inline] [] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613 [] entry_SYSCALL_64_fastpath+0x1c/0x98 Code: 00 00 41 8b 44 24 4c c1 e8 14 83 f8 07 0f 85 0a 01 00 00 e8 cd 13 f4 fe 49 8d bc 24 48 03 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 <0f> 85 e4 13 00 00 4d 8b a4 24 48 03 00 00 4d 39 e7 0f 84 49 0e