INFO: task syz-executor.3:11572 blocked for more than 143 seconds. Not tainted 5.7.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28128 11572 7346 0x00004004 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4158 schedule_timeout+0x55b/0x850 kernel/time/timer.c:1874 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x16a/0x270 kernel/sched/completion.c:138 flush_workqueue+0x403/0x14f0 kernel/workqueue.c:2831 nbd_start_device_ioctl drivers/block/nbd.c:1322 [inline] __nbd_ioctl drivers/block/nbd.c:1397 [inline] nbd_ioctl+0x7ae/0xb7f drivers/block/nbd.c:1437 __blkdev_driver_ioctl block/ioctl.c:322 [inline] blkdev_ioctl+0x25b/0x660 block/ioctl.c:718 block_ioctl+0xf9/0x140 fs/block_dev.c:2005 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0x11a/0x180 fs/ioctl.c:771 __do_sys_ioctl fs/ioctl.c:780 [inline] __se_sys_ioctl fs/ioctl.c:778 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:778 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45c829 Code: Bad RIP value. RSP: 002b:00007fb53ecb8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004e8c00 RCX: 000000000045c829 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000403 R14: 00000000004c69fa R15: 00007fb53ecb96d4 Showing all locks held in the system: 2 locks held by kworker/u4:4/182: #0: ffff8880ae637998 (&rq->lock){-.-.}-{2:2}, at: newidle_balance+0x9be/0xdb0 kernel/sched/fair.c:10512 #1: ffffffff899beb00 (rcu_read_lock){....}-{1:2}, at: __update_idle_core+0x42/0x3e0 kernel/sched/fair.c:5969 1 lock held by khungtaskd/1140: #0: ffffffff899beb00 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5754 2 locks held by kworker/u5:0/1623: #0: ffff888092f09938 ((wq_completion)knbd3-recv){+.+.}-{0:0}, at: __write_once_size include/linux/compiler.h:226 [inline] #0: ffff888092f09938 ((wq_completion)knbd3-recv){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888092f09938 ((wq_completion)knbd3-recv){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] #0: ffff888092f09938 ((wq_completion)knbd3-recv){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] #0: ffff888092f09938 ((wq_completion)knbd3-recv){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff888092f09938 ((wq_completion)knbd3-recv){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline] #0: ffff888092f09938 ((wq_completion)knbd3-recv){+.+.}-{0:0}, at: process_one_work+0x844/0x16a0 kernel/workqueue.c:2239 #1: ffffc90005587dc0 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x878/0x16a0 kernel/workqueue.c:2243 1 lock held by in:imklog/6733: #0: ffff8880a8379bb0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1140 Comm: khungtaskd Not tainted 5.7.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xa8c/0x1010 kernel/hung_task.c:289 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4115 Comm: systemd-journal Not tainted 5.7.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:43 [inline] RIP: 0010:stack_access_ok+0x37/0x130 arch/x86/kernel/unwind_orc.c:338 Code: 41 54 49 89 fc 55 48 c1 e9 03 48 89 f5 53 48 83 ec 08 0f b6 04 01 84 c0 74 08 3c 03 0f 8e af 00 00 00 41 8b 04 24 85 c0 74 68 <49> 8d 7c 24 08 48 b8 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 RSP: 0018:ffffc900016d7888 EFLAGS: 00000202 RAX: 0000000000000001 RBX: 1ffff920002daf16 RCX: 1ffff920002daf42 RDX: 0000000000000008 RSI: ffffc900016d7f38 RDI: ffffc900016d7a10 RBP: ffffc900016d7f38 R08: ffffffff8aebc264 R09: 0000000000000001 R10: 0000000000000222 R11: 000000000007001f R12: ffffc900016d7a10 R13: dffffc0000000000 R14: ffffc900016d7a60 R15: ffffc900016d7a10 FS: 00007f5a438a58c0(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5a40ccd000 CR3: 00000000904f6000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: deref_stack_reg+0x66/0xe0 arch/x86/kernel/unwind_orc.c:348 unwind_next_frame+0x10f4/0x19d0 arch/x86/kernel/unwind_orc.c:548 arch_stack_walk+0x74/0xd0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123 save_stack+0x1b/0x40 mm/kasan/common.c:49 set_track mm/kasan/common.c:57 [inline] __kasan_kmalloc mm/kasan/common.c:495 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468 slab_post_alloc_hook mm/slab.h:586 [inline] slab_alloc mm/slab.c:3320 [inline] __do_kmalloc mm/slab.c:3654 [inline] __kmalloc+0x14b/0x7a0 mm/slab.c:3665 kmalloc include/linux/slab.h:560 [inline] kzalloc include/linux/slab.h:669 [inline] lsm_cred_alloc security/security.c:532 [inline] security_prepare_creds+0x116/0x180 security/security.c:1605 prepare_creds+0x4bd/0x6b0 kernel/cred.c:285 do_faccessat+0x94/0x7a0 fs/open.c:360 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x7f5a42b619c7 Code: 83 c4 08 48 3d 01 f0 ff ff 73 01 c3 48 8b 0d c8 d4 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 b8 15 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a1 d4 2b 00 f7 d8 64 89 01 48 RSP: 002b:00007ffc963c2958 EFLAGS: 00000246 ORIG_RAX: 0000000000000015 RAX: ffffffffffffffda RBX: 00007ffc963c5870 RCX: 00007f5a42b619c7 RDX: 00007f5a435d2a00 RSI: 0000000000000000 RDI: 00005603d99e59a3 RBP: 00007ffc963c2990 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000069 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007ffc963c5870 R15: 00007ffc963c2e80