audit: type=1804 audit(1577220825.981:91): pid=12475 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op="invalid_pcr" cause="open_writers" comm="syz-executor.4" name="/root/syzkaller-testdir339298454/syzkaller.tXTZO2/133/file0" dev="sda1" ino=17011 res=1 block nbd3: Receive control failed (result -107) block nbd3: shutting down sockets ============================================ WARNING: possible recursive locking detected 4.14.160-syzkaller #0 Not tainted -------------------------------------------- kworker/u5:0/1179 is trying to acquire lock: ("knbd%d-recv"nbd->index){+.+.}, at: [] flush_workqueue+0xda/0x1400 kernel/workqueue.c:2619 but task is already holding lock: ("knbd%d-recv"nbd->index){+.+.}, at: [] work_static include/linux/workqueue.h:199 [inline] ("knbd%d-recv"nbd->index){+.+.}, at: [] set_work_data kernel/workqueue.c:619 [inline] ("knbd%d-recv"nbd->index){+.+.}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline] ("knbd%d-recv"nbd->index){+.+.}, at: [] process_one_work+0x76e/0x1600 kernel/workqueue.c:2085 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock("knbd%d-recv"nbd->index); lock("knbd%d-recv"nbd->index); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by kworker/u5:0/1179: #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+0x76e/0x1600 kernel/workqueue.c:2085 #1: ((&args->work)){+.+.}, at: [] process_one_work+0x7ab/0x1600 kernel/workqueue.c:2089 #2: (&nbd->config_lock){+.+.}, at: [] refcount_dec_and_mutex_lock lib/refcount.c:312 [inline] #2: (&nbd->config_lock){+.+.}, at: [] refcount_dec_and_mutex_lock+0x41/0x5f lib/refcount.c:307 stack backtrace: CPU: 0 PID: 1179 Comm: kworker/u5:0 Not tainted 4.14.160-syzkaller #0 kobject: 'loop1' (ffff8880a4046360): kobject_uevent_env Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 kobject: 'loop1' (ffff8880a4046360): fill_kobj_path: path = '/devices/virtual/block/loop1' Workqueue: knbd3-recv recv_work Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x142/0x197 lib/dump_stack.c:58 print_deadlock_bug kernel/locking/lockdep.c:1796 [inline] check_deadlock kernel/locking/lockdep.c:1843 [inline] validate_chain kernel/locking/lockdep.c:2444 [inline] __lock_acquire.cold+0x2bf/0x8dc kernel/locking/lockdep.c:3487 lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994 flush_workqueue+0x109/0x1400 kernel/workqueue.c:2622 drain_workqueue+0x177/0x3e0 kernel/workqueue.c:2787 kobject: 'loop4' (ffff8880a41815e0): kobject_uevent_env kobject: 'loop4' (ffff8880a41815e0): fill_kobj_path: path = '/devices/virtual/block/loop4' destroy_workqueue+0x75/0x670 kernel/workqueue.c:4100 nbd_config_put+0x43c/0x7a0 drivers/block/nbd.c:1151 recv_work+0x18d/0x1f0 drivers/block/nbd.c:730 process_one_work+0x863/0x1600 kernel/workqueue.c:2114 worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248 kthread+0x319/0x430 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 kobject: 'loop0' (ffff88808a8a17a0): kobject_uevent_env kobject: 'loop0' (ffff88808a8a17a0): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (ffff88808a8a17a0): kobject_uevent_env kobject: 'loop0' (ffff88808a8a17a0): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (ffff8880a41815e0): kobject_uevent_env kobject: 'loop4' (ffff8880a41815e0): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop1' (ffff8880a4046360): kobject_uevent_env kobject: 'loop1' (ffff8880a4046360): fill_kobj_path: path = '/devices/virtual/block/loop1' kobject: 'loop0' (ffff88808a8a17a0): kobject_uevent_env kobject: 'loop0' (ffff88808a8a17a0): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop0' (ffff88808a8a17a0): kobject_uevent_env kobject: 'loop0' (ffff88808a8a17a0): fill_kobj_path: path = '/devices/virtual/block/loop0' kobject: 'loop4' (ffff8880a41815e0): kobject_uevent_env kobject: 'loop4' (ffff8880a41815e0): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop4' (ffff8880a41815e0): kobject_uevent_env kobject: 'loop4' (ffff8880a41815e0): fill_kobj_path: path = '/devices/virtual/block/loop4' kobject: 'loop4' (ffff8880a41815e0): kobject_uevent_env kobject: 'loop4' (ffff8880a41815e0): fill_kobj_path: path = '/devices/virtual/block/loop4'