[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 57.938957][ T26] audit: type=1800 audit(1570563471.183:25): pid=8683 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 57.978207][ T26] audit: type=1800 audit(1570563471.183:26): pid=8683 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 58.016873][ T26] audit: type=1800 audit(1570563471.183:27): pid=8683 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.1.20' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program syzkaller login: [ 153.921169][ T1523] block nbd5: Receive control failed (result -22) [ 153.929637][ T1523] block nbd3: Receive control failed (result -22) [ 153.936495][ T8854] block nbd1: Receive control failed (result -22) [ 153.944041][ T1523] block nbd0: Receive control failed (result -22) [ 153.946494][ T8845] block nbd3: shutting down sockets [ 153.952696][ T8844] block nbd5: shutting down sockets [ 153.956284][ T8859] block nbd4: Receive control failed (result -22) executing program executing program [ 153.962330][ T8854] block nbd2: Receive control failed (result -22) [ 153.976364][ T8846] block nbd1: shutting down sockets [ 153.983368][ T8847] block nbd4: shutting down sockets [ 153.990406][ T8839] block nbd0: shutting down sockets [ 153.994880][ T8848] block nbd2: shutting down sockets executing program executing program executing program executing program [ 154.025574][ T8854] block nbd3: Receive control failed (result -22) [ 154.035597][ T8854] block nbd5: Receive control failed (result -22) [ 154.041027][ T8862] block nbd3: shutting down sockets [ 154.051184][ T8863] block nbd5: shutting down sockets executing program [ 154.078844][ T8854] block nbd0: Receive control failed (result -22) [ 154.085996][ T8854] block nbd4: Receive control failed (result -22) [ 154.096250][ T8867] block nbd0: shutting down sockets [ 154.102745][ T8854] block nbd2: Receive control failed (result -22) [ 154.103895][ T8868] block nbd4: shutting down sockets [ 154.126344][ T8870] block nbd2: shutting down sockets [ 154.136198][ T8854] block nbd3: Receive control failed (result -22) [ 154.143007][ T1523] block nbd1: Receive control failed (result -22) [ 154.155167][ T8874] block nbd3: shutting down sockets executing program executing program executing program executing program executing program executing program [ 154.180874][ T8869] block nbd1: shutting down sockets [ 154.194941][ T8854] block nbd5: Receive control failed (result -22) [ 154.203743][ T8877] block nbd5: shutting down sockets [ 154.227460][ T8854] block nbd4: Receive control failed (result -22) [ 154.237036][ T8854] block nbd2: Receive control failed (result -22) [ 154.237311][ T1523] block nbd0: Receive control failed (result -22) [ 154.244569][ T8854] block nbd1: Receive control failed (result -22) [ 154.259565][ T8881] block nbd2: shutting down sockets [ 154.269654][ T8883] block nbd4: shutting down sockets executing program executing program [ 154.288987][ T1523] block nbd3: Receive control failed (result -22) [ 154.303597][ T8887] block nbd3: shutting down sockets [ 154.303614][ T8886] block nbd1: shutting down sockets [ 154.310728][ T1523] block nbd5: Receive control failed (result -22) [ 154.323716][ T8891] block nbd5: shutting down sockets executing program executing program executing program [ 154.335374][ T8882] block nbd0: shutting down sockets [ 154.351997][ T1523] block nbd4: Receive control failed (result -22) [ 154.368918][ T8892] block nbd4: shutting down sockets [ 154.382488][ T1523] block nbd2: Receive control failed (result -22) executing program executing program [ 154.390959][ T8896] block nbd2: shutting down sockets [ 154.403261][ T1523] block nbd3: Receive control failed (result -22) [ 154.413773][ T1523] block nbd5: Receive control failed (result -22) [ 154.423325][ T8899] block nbd5: shutting down sockets [ 154.432672][ T1523] block nbd1: Receive control failed (result -22) executing program executing program [ 154.432786][ T8898] block nbd3: shutting down sockets [ 154.445335][ T1523] block nbd2: Receive control failed (result -22) [ 154.455047][ T8906] block nbd2: shutting down sockets [ 154.466176][ T8902] block nbd1: shutting down sockets [ 154.472321][ T1523] block nbd4: Receive control failed (result -22) [ 154.482470][ T1523] block nbd0: Receive control failed (result -22) executing program executing program [ 154.484073][ T8904] block nbd4: shutting down sockets [ 154.495901][ T8903] block nbd0: shutting down sockets executing program executing program executing program executing program [ 154.544258][ T1523] block nbd5: Receive control failed (result -22) [ 154.553911][ T1523] block nbd2: Receive control failed (result -22) [ 154.558037][ T8912] block nbd5: shutting down sockets [ 154.577570][ T8911] block nbd2: shutting down sockets [ 154.585289][ T1523] block nbd3: Receive control failed (result -22) [ 154.592511][ T1523] block nbd0: Receive control failed (result -22) [ 154.601028][ T1523] block nbd1: Receive control failed (result -22) [ 154.606245][ T8916] block nbd0: shutting down sockets [ 154.614972][ T8913] block nbd1: shutting down sockets [ 154.632425][ T8917] block nbd3: shutting down sockets executing program executing program [ 154.640798][ T1523] block nbd4: Receive control failed (result -22) [ 154.649144][ T8918] block nbd4: shutting down sockets [ 154.660136][ T1523] block nbd5: Receive control failed (result -22) [ 154.668879][ T8923] block nbd5: shutting down sockets [ 154.682065][ T1523] block nbd2: Receive control failed (result -22) executing program executing program executing program executing program executing program [ 154.693022][ T8924] block nbd2: shutting down sockets [ 154.711297][ T1523] block nbd4: Receive control failed (result -22) [ 154.711642][ T8854] block nbd3: Receive control failed (result -22) [ 154.728226][ T8928] block nbd4: shutting down sockets [ 154.735374][ T8930] block nbd3: shutting down sockets executing program [ 154.741084][ T8854] block nbd5: Receive control failed (result -22) [ 154.750787][ T8854] block nbd0: Receive control failed (result -22) [ 154.757677][ T8935] block nbd5: shutting down sockets [ 154.773533][ T8854] block nbd1: Receive control failed (result -22) [ 154.783428][ T8927] block nbd1: shutting down sockets executing program [ 154.796165][ T8929] block nbd0: shutting down sockets [ 154.801663][ T8854] block nbd2: Receive control failed (result -22) [ 154.830029][ T8937] block nbd2: shutting down sockets executing program executing program executing program executing program executing program [ 154.843456][ T8854] block nbd5: Receive control failed (result -22) [ 154.852097][ T8939] block nbd5: shutting down sockets [ 154.871865][ T8854] block nbd3: Receive control failed (result -22) [ 154.880765][ T8946] block nbd3: shutting down sockets [ 154.886678][ T8854] block nbd1: Receive control failed (result -22) executing program [ 154.894222][ T8854] block nbd0: Receive control failed (result -22) [ 154.895397][ T8942] block nbd1: shutting down sockets [ 154.907676][ T8943] block nbd0: shutting down sockets [ 154.918871][ T1523] block nbd4: Receive control failed (result -22) [ 154.918878][ T8854] block nbd2: Receive control failed (result -22) [ 154.920802][ T8945] block nbd2: shutting down sockets [ 154.940665][ T8944] block nbd4: shutting down sockets executing program executing program [ 154.946492][ T1523] block nbd5: Receive control failed (result -22) [ 154.955355][ T8952] block nbd5: shutting down sockets [ 154.979005][ T1523] block nbd3: Receive control failed (result -22) [ 154.989586][ T8954] block nbd3: shutting down sockets executing program executing program executing program executing program [ 155.004384][ T1523] block nbd1: Receive control failed (result -22) [ 155.013283][ T8956] block nbd1: shutting down sockets [ 155.023559][ T1523] block nbd0: Receive control failed (result -22) [ 155.031417][ T1523] block nbd2: Receive control failed (result -22) [ 155.032134][ T8957] block nbd0: shutting down sockets executing program [ 155.050948][ T1523] block nbd4: Receive control failed (result -22) [ 155.060351][ T8961] block nbd4: shutting down sockets [ 155.068812][ T1523] block nbd5: Receive control failed (result -22) [ 155.077612][ T8959] block nbd5: shutting down sockets [ 155.083974][ T8960] block nbd2: shutting down sockets [ 155.097372][ T1523] block nbd3: Receive control failed (result -22) executing program executing program executing program executing program executing program [ 155.105612][ T8966] block nbd3: shutting down sockets [ 155.131458][ T1523] block nbd0: Receive control failed (result -22) [ 155.138911][ T8854] block nbd2: Receive control failed (result -22) [ 155.146709][ T1523] block nbd1: Receive control failed (result -22) [ 155.150492][ T8972] block nbd0: shutting down sockets [ 155.159087][ T8970] block nbd2: shutting down sockets [ 155.165003][ T1523] block nbd5: Receive control failed (result -22) [ 155.172700][ T1523] block nbd4: Receive control failed (result -22) executing program [ 155.173631][ T8969] block nbd5: shutting down sockets [ 155.186774][ T8971] block nbd4: shutting down sockets [ 155.220711][ T1523] block nbd3: Receive control failed (result -22) executing program executing program executing program [ 155.229007][ T8973] block nbd1: shutting down sockets [ 155.230573][ T8975] block nbd3: shutting down sockets [ 155.262228][ T1523] block nbd0: Receive control failed (result -22) [ 155.268654][ T8854] block nbd2: Receive control failed (result -22) executing program executing program [ 155.277328][ T8982] block nbd2: shutting down sockets [ 155.283636][ T8854] block nbd4: Receive control failed (result -22) [ 155.292457][ T8981] block nbd4: shutting down sockets [ 155.303956][ T8985] block nbd0: shutting down sockets [ 155.320404][ T8854] block nbd5: Receive control failed (result -22) executing program executing program [ 155.329054][ T8987] block nbd5: shutting down sockets [ 155.339923][ T8854] block nbd1: Receive control failed (result -22) [ 155.350037][ T8990] block nbd1: shutting down sockets [ 155.358297][ T8854] block nbd3: Receive control failed (result -22) [ 155.365799][ T8854] block nbd2: Receive control failed (result -22) [ 155.376008][ T8993] block nbd2: shutting down sockets executing program executing program executing program executing program [ 155.383030][ T8989] block nbd3: shutting down sockets executing program executing program [ 155.410683][ T8854] block nbd4: Receive control failed (result -22) [ 155.419161][ T8995] block nbd4: shutting down sockets [ 155.426372][ T8854] block nbd5: Receive control failed (result -22) [ 155.435270][ T8997] block nbd5: shutting down sockets [ 155.442496][ T8854] block nbd0: Receive control failed (result -22) [ 155.455283][ T8854] block nbd1: Receive control failed (result -22) [ 155.456708][ T8996] block nbd0: shutting down sockets [ 155.470533][ T8999] block nbd1: shutting down sockets [ 155.492076][ T8854] block nbd3: Receive control failed (result -22) [ 155.499682][ T8854] block nbd2: Receive control failed (result -22) executing program executing program executing program executing program [ 155.513800][ T9004] block nbd3: shutting down sockets [ 155.514802][ T9003] block nbd2: shutting down sockets [ 155.543360][ T8854] block nbd4: Receive control failed (result -22) [ 155.550726][ T1523] block nbd1: Receive control failed (result -22) [ 155.558148][ T8854] block nbd4: shutting down sockets [ 155.558406][ T1523] block nbd5: Receive control failed (result -22) [ 155.565292][ T9009] block nbd1: shutting down sockets [ 155.577224][ T9008] block nbd5: shutting down sockets [ 155.582888][ T1523] block nbd0: Receive control failed (result -22) [ 155.583645][ T8854] [ 155.591330][ T9010] block nbd0: shutting down sockets [ 155.591698][ T8854] ============================================ [ 155.603175][ T8854] WARNING: possible recursive locking detected [ 155.609334][ T8854] 5.4.0-rc2+ #0 Not tainted executing program [ 155.613815][ T8854] -------------------------------------------- [ 155.619963][ T8854] kworker/u5:1/8854 is trying to acquire lock: [ 155.626377][ T8854] ffff8880a1406528 ((wq_completion)knbd4-recv){+.+.}, at: flush_workqueue+0xf7/0x14c0 [ 155.635935][ T8854] [ 155.635935][ T8854] but task is already holding lock: [ 155.643305][ T8854] ffff8880a1406528 ((wq_completion)knbd4-recv){+.+.}, at: process_one_work+0x88b/0x1740 [ 155.653178][ T8854] [ 155.653178][ T8854] other info that might help us debug this: [ 155.661228][ T8854] Possible unsafe locking scenario: [ 155.661228][ T8854] [ 155.669469][ T8854] CPU0 [ 155.672733][ T8854] ---- [ 155.676007][ T8854] lock((wq_completion)knbd4-recv); [ 155.681265][ T8854] lock((wq_completion)knbd4-recv); [ 155.686529][ T8854] [ 155.686529][ T8854] *** DEADLOCK *** [ 155.686529][ T8854] [ 155.694660][ T8854] May be due to missing lock nesting notation [ 155.694660][ T8854] [ 155.702968][ T8854] 3 locks held by kworker/u5:1/8854: [ 155.708251][ T8854] #0: ffff8880a1406528 ((wq_completion)knbd4-recv){+.+.}, at: process_one_work+0x88b/0x1740 [ 155.718832][ T8854] #1: ffff888099787dc0 ((work_completion)(&args->work)){+.+.}, at: process_one_work+0x8c1/0x1740 [ 155.729421][ T8854] #2: ffff8880a30c5578 (&nbd->config_lock){+.+.}, at: refcount_dec_and_mutex_lock+0x56/0x90 [ 155.739669][ T8854] [ 155.739669][ T8854] stack backtrace: [ 155.745992][ T8854] CPU: 0 PID: 8854 Comm: kworker/u5:1 Not tainted 5.4.0-rc2+ #0 [ 155.753746][ T8854] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 155.763794][ T8854] Workqueue: knbd4-recv recv_work [ 155.768815][ T8854] Call Trace: [ 155.772146][ T8854] dump_stack+0x172/0x1f0 [ 155.776458][ T8854] __lock_acquire.cold+0x15d/0x385 [ 155.781549][ T8854] ? mark_held_locks+0xf0/0xf0 [ 155.786644][ T8854] lock_acquire+0x190/0x410 [ 155.791132][ T8854] ? flush_workqueue+0xf7/0x14c0 [ 155.796054][ T8854] flush_workqueue+0x126/0x14c0 [ 155.800903][ T8854] ? flush_workqueue+0xf7/0x14c0 [ 155.805826][ T8854] ? lock_downgrade+0x920/0x920 [ 155.810684][ T8854] ? drain_workqueue+0x2b/0x470 [ 155.815520][ T8854] ? debug_check_no_obj_freed+0x20a/0x43f [ 155.821222][ T8854] ? find_held_lock+0x35/0x130 [ 155.825977][ T8854] ? pwq_unbound_release_workfn+0x2f0/0x2f0 [ 155.831848][ T8854] ? mark_lock+0xc2/0x1220 [ 155.836246][ T8854] drain_workqueue+0x1b4/0x470 [ 155.840986][ T8854] ? drain_workqueue+0x1b4/0x470 [ 155.845909][ T8854] ? kfree+0x226/0x2c0 [ 155.849960][ T8854] destroy_workqueue+0x21/0x700 [ 155.854788][ T8854] ? nbd_config_put+0x378/0x870 [ 155.859622][ T8854] nbd_config_put+0x3dd/0x870 executing program executing program executing program [ 155.864277][ T8854] recv_work+0x19b/0x200 [ 155.868511][ T8854] process_one_work+0x9af/0x1740 [ 155.873433][ T8854] ? pwq_dec_nr_in_flight+0x320/0x320 [ 155.878780][ T8854] ? lock_acquire+0x190/0x410 [ 155.883438][ T8854] worker_thread+0x98/0xe40 [ 155.887987][ T8854] kthread+0x361/0x430 [ 155.892077][ T8854] ? process_one_work+0x1740/0x1740 [ 155.897266][ T8854] ? kthread_cancel_delayed_work_sync+0x20/0x20 [ 155.903487][ T8854] ret_from_fork+0x24/0x30 executing program executing program