======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
udevd/5756 is trying to acquire lock:
ffff88803f19c668 (&nsock->tx_lock){+.+.}-{4:4}, at: nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
ffff88803f19c668 (&nsock->tx_lock){+.+.}-{4:4}, at: nbd_queue_rq+0x428/0x1080 drivers/block/nbd.c:1207

but task is already holding lock:
ffff888037a7e178 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #6 (&cmd->lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:820
       nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199
       blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
       __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386
       blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949
       blk_mq_flush_plug_list block/blk-mq.c:2997 [inline]
       blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x584/0x6c0 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x543/0xbf0 block/blk-core.c:753
       submit_bio_noacct+0xd18/0x2000 block/blk-core.c:884
       blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
       submit_bh_wbc+0x681/0x890 fs/buffer.c:2737
       submit_bh fs/buffer.c:2742 [inline]
       block_read_full_folio+0x264/0x8e0 fs/buffer.c:2344
       filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2502
       do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4107
       read_mapping_folio include/linux/pagemap.h:1017 [inline]
       read_part_sector+0xd1/0x370 block/partitions/core.c:724
       adfspart_check_ICS+0x91/0x7d0 block/partitions/acorn.c:356
       check_partition block/partitions/core.c:143 [inline]
       blk_add_partitions block/partitions/core.c:591 [inline]
       bdev_disk_changed+0x7a3/0x1250 block/partitions/core.c:695
       blkdev_get_whole+0x187/0x290 block/bdev.c:756
       bdev_open+0x2c7/0xe40 block/bdev.c:965
       blkdev_open+0x34e/0x4f0 block/fops.c:697
       do_dentry_open+0x6ab/0x14d0 fs/open.c:947
       vfs_open+0x82/0x3f0 fs/open.c:1079
       do_open fs/namei.c:4699 [inline]
       path_openat+0x208c/0x31a0 fs/namei.c:4858
       do_file_open+0x20e/0x430 fs/namei.c:4887
       do_sys_openat2+0x10d/0x1e0 fs/open.c:1364
       do_sys_open fs/open.c:1370 [inline]
       __do_sys_openat fs/open.c:1386 [inline]
       __se_sys_openat fs/open.c:1381 [inline]
       __x64_sys_openat+0x12d/0x210 fs/open.c:1381
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (set->srcu){.+.+}-{0:0}:
       srcu_lock_sync include/linux/srcu.h:199 [inline]
       __synchronize_srcu+0xa2/0x300 kernel/rcu/srcutree.c:1481
       blk_mq_wait_quiesce_done block/blk-mq.c:284 [inline]
       blk_mq_wait_quiesce_done block/blk-mq.c:281 [inline]
       blk_mq_quiesce_queue block/blk-mq.c:304 [inline]
       blk_mq_quiesce_queue+0x149/0x1c0 block/blk-mq.c:299
       elevator_switch+0x17b/0x7e0 block/elevator.c:576
       elevator_change+0x352/0x530 block/elevator.c:681
       elevator_set_default+0x29e/0x360 block/elevator.c:754
       blk_register_queue+0x48e/0x630 block/blk-sysfs.c:987
       __add_disk+0x73f/0xe40 block/genhd.c:528
       add_disk_fwnode+0x118/0x5c0 block/genhd.c:597
       add_disk include/linux/blkdev.h:794 [inline]
       nbd_dev_add+0x77a/0xb10 drivers/block/nbd.c:1984
       nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692
       do_one_initcall+0x121/0x750 init/main.c:1392
       do_initcall_level init/main.c:1454 [inline]
       do_initcalls init/main.c:1470 [inline]
       do_basic_setup init/main.c:1490 [inline]
       kernel_init_freeable+0x6ea/0x7b0 init/main.c:1703
       kernel_init+0x1f/0x1e0 init/main.c:1593
       ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #4 (&q->elevator_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:820
       elevator_change+0x1bc/0x530 block/elevator.c:679
       elevator_set_none+0x92/0xf0 block/elevator.c:769
       blk_mq_elv_switch_none block/blk-mq.c:5134 [inline]
       __blk_mq_update_nr_hw_queues block/blk-mq.c:5179 [inline]
       blk_mq_update_nr_hw_queues+0x4c1/0x15f0 block/blk-mq.c:5244
       nbd_start_device+0x1a6/0xbd0 drivers/block/nbd.c:1489
       nbd_genl_connect+0xff2/0x1a40 drivers/block/nbd.c:2239
       genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114
       genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
       genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209
       netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2555
       genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
       netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
       netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1344
       netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1899
       sock_sendmsg_nosec net/socket.c:787 [inline]
       __sock_sendmsg net/socket.c:802 [inline]
       ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2699
       ___sys_sendmsg+0x190/0x1e0 net/socket.c:2753
       __sys_sendmsg+0x170/0x220 net/socket.c:2785
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&q->q_usage_counter(io)#50){++++}-{0:0}:
       blk_alloc_queue+0x610/0x790 block/blk-core.c:461
       blk_mq_alloc_queue+0x174/0x290 block/blk-mq.c:4453
       __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4500
       nbd_dev_add+0x492/0xb10 drivers/block/nbd.c:1954
       nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692
       do_one_initcall+0x121/0x750 init/main.c:1392
       do_initcall_level init/main.c:1454 [inline]
       do_initcalls init/main.c:1470 [inline]
       do_basic_setup init/main.c:1490 [inline]
       kernel_init_freeable+0x6ea/0x7b0 init/main.c:1703
       kernel_init+0x1f/0x1e0 init/main.c:1593
       ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #2 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:4320 [inline]
       fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4334
       might_alloc include/linux/sched/mm.h:317 [inline]
       slab_pre_alloc_hook mm/slub.c:4521 [inline]
       slab_alloc_node mm/slub.c:4876 [inline]
       kmem_cache_alloc_node_noprof+0x53/0x6f0 mm/slub.c:4951
       __alloc_skb+0x140/0x710 net/core/skbuff.c:702
       alloc_skb include/linux/skbuff.h:1385 [inline]
       __ip6_append_data+0x34f1/0x4bf0 net/ipv6/ip6_output.c:1701
       ip6_append_data net/ipv6/ip6_output.c:1891 [inline]
       ip6_append_data+0x10b/0x410 net/ipv6/ip6_output.c:1860
       rawv6_sendmsg+0x169c/0x4420 net/ipv6/raw.c:913
       inet_sendmsg+0x11c/0x140 net/ipv4/af_inet.c:866
       sock_sendmsg_nosec net/socket.c:787 [inline]
       __sock_sendmsg net/socket.c:802 [inline]
       ____sys_sendmsg+0x98d/0xb70 net/socket.c:2699
       ___sys_sendmsg+0x190/0x1e0 net/socket.c:2753
       __sys_sendmsg+0x170/0x220 net/socket.c:2785
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_sock_nested+0x41/0xf0 net/core/sock.c:3792
       lock_sock include/net/sock.h:1713 [inline]
       inet_shutdown+0x67/0x410 net/ipv4/af_inet.c:915
       nbd_mark_nsock_dead+0xae/0x5c0 drivers/block/nbd.c:318
       recv_work+0x5fb/0x8c0 drivers/block/nbd.c:1021
       process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314
       process_scheduled_works kernel/workqueue.c:3397 [inline]
       worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478
       kthread+0x370/0x450 kernel/kthread.c:436
       ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #0 (&nsock->tx_lock){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:820
       nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
       nbd_queue_rq+0x428/0x1080 drivers/block/nbd.c:1207
       blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148
       __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
       blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
       __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386
       blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949
       blk_mq_flush_plug_list block/blk-mq.c:2997 [inline]
       blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969
       __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x584/0x6c0 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x543/0xbf0 block/blk-core.c:753
       submit_bio_noacct+0xd18/0x2000 block/blk-core.c:884
       blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
       submit_bh_wbc+0x681/0x890 fs/buffer.c:2737
       submit_bh fs/buffer.c:2742 [inline]
       block_read_full_folio+0x264/0x8e0 fs/buffer.c:2344
       filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2502
       do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4107
       read_mapping_folio include/linux/pagemap.h:1017 [inline]
       read_part_sector+0xd1/0x370 block/partitions/core.c:724
       adfspart_check_ICS+0x91/0x7d0 block/partitions/acorn.c:356
       check_partition block/partitions/core.c:143 [inline]
       blk_add_partitions block/partitions/core.c:591 [inline]
       bdev_disk_changed+0x7a3/0x1250 block/partitions/core.c:695
       blkdev_get_whole+0x187/0x290 block/bdev.c:756
       bdev_open+0x2c7/0xe40 block/bdev.c:965
       blkdev_open+0x34e/0x4f0 block/fops.c:697
       do_dentry_open+0x6ab/0x14d0 fs/open.c:947
       vfs_open+0x82/0x3f0 fs/open.c:1079
       do_open fs/namei.c:4699 [inline]
       path_openat+0x208c/0x31a0 fs/namei.c:4858
       do_file_open+0x20e/0x430 fs/namei.c:4887
       do_sys_openat2+0x10d/0x1e0 fs/open.c:1364
       do_sys_open fs/open.c:1370 [inline]
       __do_sys_openat fs/open.c:1386 [inline]
       __se_sys_openat fs/open.c:1381 [inline]
       __x64_sys_openat+0x12d/0x210 fs/open.c:1381
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &nsock->tx_lock --> set->srcu --> &cmd->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&cmd->lock);
                               lock(set->srcu);
                               lock(&cmd->lock);
  lock(&nsock->tx_lock);

 *** DEADLOCK ***

3 locks held by udevd/5756:
 #0: ffff888029a46350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe40 block/bdev.c:953
 #1: ffff888029208098 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
 #1: ffff888029208098 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
 #1: ffff888029208098 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x22e/0x670 block/blk-mq.c:2386
 #2: ffff888037a7e178 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199

stack backtrace:
CPU: 0 UID: 0 PID: 5756 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043
 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:820
 nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
 nbd_queue_rq+0x428/0x1080 drivers/block/nbd.c:1207
 blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
 __blk_mq_sched_dispatch_requests+0xcea/0x1620 block/blk-mq-sched.c:307
 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329
 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386
 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949
 blk_mq_flush_plug_list block/blk-mq.c:2997 [inline]
 blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969
 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230
 blk_finish_plug block/blk-core.c:1257 [inline]
 __submit_bio+0x584/0x6c0 block/blk-core.c:649
 __submit_bio_noacct_mq block/blk-core.c:722 [inline]
 submit_bio_noacct_nocheck+0x543/0xbf0 block/blk-core.c:753
 submit_bio_noacct+0xd18/0x2000 block/blk-core.c:884
 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
 submit_bh_wbc+0x681/0x890 fs/buffer.c:2737
 submit_bh fs/buffer.c:2742 [inline]
 block_read_full_folio+0x264/0x8e0 fs/buffer.c:2344
 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2502
 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4107
 read_mapping_folio include/linux/pagemap.h:1017 [inline]
 read_part_sector+0xd1/0x370 block/partitions/core.c:724
 adfspart_check_ICS+0x91/0x7d0 block/partitions/acorn.c:356
 check_partition block/partitions/core.c:143 [inline]
 blk_add_partitions block/partitions/core.c:591 [inline]
 bdev_disk_changed+0x7a3/0x1250 block/partitions/core.c:695
 blkdev_get_whole+0x187/0x290 block/bdev.c:756
 bdev_open+0x2c7/0xe40 block/bdev.c:965
 blkdev_open+0x34e/0x4f0 block/fops.c:697
 do_dentry_open+0x6ab/0x14d0 fs/open.c:947
 vfs_open+0x82/0x3f0 fs/open.c:1079
 do_open fs/namei.c:4699 [inline]
 path_openat+0x208c/0x31a0 fs/namei.c:4858
 do_file_open+0x20e/0x430 fs/namei.c:4887
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9c0dea7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fff91cebf40 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f9c0e573880 RCX: 00007f9c0dea7407
RDX: 00000000000a0800 RSI: 000055f00121cbf0 RDI: ffffffffffffff9c
RBP: 000055f000fb22c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055f0011f8320
R13: 000055f0011ed8d0 R14: 0000000000000000 R15: 000055f0011f8320
 </TASK>
block nbd1: Dead connection, failed to find a fallback
block nbd1: shutting down sockets
I/O error, dev nbd1, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Buffer I/O error on dev nbd1, logical block 0, async page read
I/O error, dev nbd1, sector 2 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Buffer I/O error on dev nbd1, logical block 1, async page read
I/O error, dev nbd1, sector 4 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Buffer I/O error on dev nbd1, logical block 2, async page read
I/O error, dev nbd1, sector 6 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Buffer I/O error on dev nbd1, logical block 3, async page read
I/O error, dev nbd1, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Buffer I/O error on dev nbd1, logical block 0, async page read
I/O error, dev nbd1, sector 2 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Buffer I/O error on dev nbd1, logical block 1, async page read
I/O error, dev nbd1, sector 4 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Buffer I/O error on dev nbd1, logical block 2, async page read
I/O error, dev nbd1, sector 6 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Buffer I/O error on dev nbd1, logical block 3, async page read
I/O error, dev nbd1, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Buffer I/O error on dev nbd1, logical block 0, async page read
I/O error, dev nbd1, sector 2 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
Buffer I/O error on dev nbd1, logical block 1, async page read
ldm_validate_partition_table(): Disk read failed.
Dev nbd1: unable to read RDB block 0
 nbd1: unable to read partition table
ldm_validate_partition_table(): Disk read failed.
Dev nbd1: unable to read RDB block 0
 nbd1: unable to read partition table