R13: 0000000000000c4e R14: 00000000004ca0d5 R15: 0000000000000002 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 NOHZ: local_softirq_pending 08 INFO: task syz-executor.1:10644 blocked for more than 140 seconds. Not tainted 4.14.176-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28672 10644 6353 0x00000004 Call Trace: schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x946/0xe40 kernel/time/timer.c:1723 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common kernel/sched/completion.c:123 [inline] wait_for_completion+0x241/0x390 kernel/sched/completion.c:144 flush_workqueue+0x3d1/0x13f0 kernel/workqueue.c:2676 nbd_start_device_ioctl drivers/block/nbd.c:1249 [inline] __nbd_ioctl drivers/block/nbd.c:1320 [inline] nbd_ioctl+0x4e1/0xa30 drivers/block/nbd.c:1360 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x91d/0x17d0 block/ioctl.c:594 block_ioctl+0xd9/0x120 fs/block_dev.c:1881 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45c889 RSP: 002b:00007f6fef67bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f6fef67c6d4 RCX: 000000000045c889 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000004 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000403 R14: 00000000004c6a47 R15: 000000000076bf0c Showing all locks held in the system: 1 lock held by khungtaskd/1057: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4544 2 locks held by kworker/u5:0/1191: #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] #0: ("knbd%d-recv"nbd->index){+.+.}, at: [] process_one_work+0x727/0x1540 kernel/workqueue.c:2087 #1: ((&args->work)){+.+.}, at: [] process_one_work+0x761/0x1540 kernel/workqueue.c:2091 1 lock held by in:imklog/6033: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0xa6/0xc0 fs/file.c:769 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1057 Comm: khungtaskd Not tainted 4.14.176-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x13e/0x194 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x139/0x17e lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5e2/0xb80 kernel/hung_task.c:274 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 3635 Comm: systemd-journal Not tainted 4.14.176-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880941be600 task.stack: ffff8880941c0000 RIP: 0010:__debug_check_no_obj_freed lib/debugobjects.c:741 [inline] RIP: 0010:debug_check_no_obj_freed+0x169/0x6e4 lib/debugobjects.c:776 RSP: 0018:ffff8880941c7b18 EFLAGS: 00000002 RAX: 0000000000000007 RBX: ffff888088511a48 RCX: 0000000087dc6952 RDX: 1ffff11012fc8431 RSI: ffff8880941c7b90 RDI: ffff888097e421a0 RBP: ffff8880a01020c8 R08: 0000000000000082 R09: ffffffff8a0658a0 R10: ffff8880941beea8 R11: ffff8880941be600 R12: dffffc0000000000 R13: ffff8880941c7bb0 R14: ffffffff8a6da288 R15: ffff888097e42188 FS: 00007fe996c038c0(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe994009000 CR3: 0000000094bc9000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: free_pages_prepare mm/page_alloc.c:1063 [inline] __free_pages_ok+0x22a/0xdf0 mm/page_alloc.c:1256 slab_destroy+0x1f/0x50 mm/slab.c:1723 slabs_destroy+0x6a/0x90 mm/slab.c:1739 cache_flusharray mm/slab.c:3483 [inline] ___cache_free+0x206/0x2b0 mm/slab.c:3525 qlink_free mm/kasan/quarantine.c:147 [inline] qlist_free_all+0x79/0x140 mm/kasan/quarantine.c:166 quarantine_reduce+0x140/0x170 mm/kasan/quarantine.c:259 kasan_kmalloc+0x95/0xe0 mm/kasan/kasan.c:536 slab_post_alloc_hook mm/slab.h:442 [inline] slab_alloc mm/slab.c:3390 [inline] kmem_cache_alloc+0x114/0x770 mm/slab.c:3550 getname_flags fs/namei.c:138 [inline] getname_flags+0xc8/0x560 fs/namei.c:128 do_sys_open+0x1c4/0x3f0 fs/open.c:1075 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x7fe996193840 RSP: 002b:00007ffd20c374c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007ffd20c377d0 RCX: 00007fe996193840 RDX: 00000000000001a0 RSI: 0000000000080042 RDI: 000055b38ff41be0 RBP: 000000000000000d R08: 00000000000001e0 R09: 00000000ffffffff R10: 0000000000000069 R11: 0000000000000246 R12: 00000000ffffffff R13: 000055b38ff34060 R14: 00007ffd20c37790 R15: 000055b38ff41a00 Code: 4d 85 ff 0f 84 fc 02 00 00 49 8d 75 e0 31 c0 4c 89 fa 48 c1 ea 03 42 80 3c 22 00 0f 85 eb 02 00 00 49 8d 7f 18 83 c0 01 49 8b 1f <48> 89 fa 48 c1 ea 03 42 80 3c 22 00 0f 85 f8 02 00 00 49 8b 6f