syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
udevd/5839 is trying to acquire lock:
ffff8880354fe470 (&nsock->tx_lock){+.+.}-{4:4}, at: nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
ffff8880354fe470 (&nsock->tx_lock){+.+.}-{4:4}, at: nbd_queue_rq+0x37b/0x1100 drivers/block/nbd.c:1207

but task is already holding lock:
ffff888032d88180 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc6/0x1100 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:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       nbd_queue_rq+0xc6/0x1100 drivers/block/nbd.c:1199
       blk_mq_dispatch_rq_list+0xa70/0x1910 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+0xdcc/0x1600 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386
       blk_mq_dispatch_list+0xd16/0xe10 include/linux/spinlock.h:-1
       blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997
       __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x28d/0x580 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x2f4/0xa70 block/blk-core.c:753
       submit_bh fs/buffer.c:2826 [inline]
       block_read_full_folio+0x599/0x830 fs/buffer.c:2444
       filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501
       do_read_cache_folio+0x358/0x590 mm/filemap.c:4101
       read_mapping_folio include/linux/pagemap.h:1028 [inline]
       read_part_sector+0xb6/0x2b0 block/partitions/core.c:723
       adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:142 [inline]
       blk_add_partitions block/partitions/core.c:590 [inline]
       bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694
       blkdev_get_whole+0x380/0x510 block/bdev.c:764
       bdev_open+0x31e/0xd30 block/bdev.c:973
       blkdev_open+0x470/0x610 block/fops.c:697
       do_dentry_open+0x785/0x14e0 fs/open.c:949
       vfs_open+0x3b/0x340 fs/open.c:1081
       do_open fs/namei.c:4671 [inline]
       path_openat+0x2e08/0x3860 fs/namei.c:4830
       do_file_open+0x23e/0x4a0 fs/namei.c:4859
       do_sys_openat2+0x113/0x200 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 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+0xca/0x3e0 kernel/rcu/srcutree.c:1505
       elevator_switch+0x1e8/0x7a0 block/elevator.c:576
       elevator_change+0x2cc/0x450 block/elevator.c:681
       elevator_set_default+0x36c/0x430 block/elevator.c:754
       blk_register_queue+0x366/0x430 block/blk-sysfs.c:946
       __add_disk+0x677/0xd50 block/genhd.c:528
       add_disk_fwnode+0xfb/0x480 block/genhd.c:597
       add_disk include/linux/blkdev.h:785 [inline]
       nbd_dev_add+0x72c/0xb50 drivers/block/nbd.c:1984
       nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692
       do_one_initcall+0x250/0x8d0 init/main.c:1382
       do_initcall_level+0x104/0x190 init/main.c:1444
       do_initcalls+0x59/0xa0 init/main.c:1460
       kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692
       kernel_init+0x1d/0x1d0 init/main.c:1582
       ret_from_fork+0x51e/0xb90 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:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       elevator_change+0x1b3/0x450 block/elevator.c:679
       elevator_set_none+0xb5/0x140 block/elevator.c:769
       blk_mq_elv_switch_none block/blk-mq.c:5110 [inline]
       __blk_mq_update_nr_hw_queues block/blk-mq.c:5155 [inline]
       blk_mq_update_nr_hw_queues+0x5e7/0x1a60 block/blk-mq.c:5220
       nbd_start_device+0x17f/0xb10 drivers/block/nbd.c:1489
       nbd_genl_connect+0x165b/0x1cf0 drivers/block/nbd.c:2239
       genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114
       genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
       genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209
       netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
       genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
       netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
       netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
       netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
       sock_sendmsg_nosec net/socket.c:721 [inline]
       __sock_sendmsg net/socket.c:736 [inline]
       ____sys_sendmsg+0x972/0x9f0 net/socket.c:2585
       ___sys_sendmsg+0x2a5/0x360 net/socket.c:2639
       __sys_sendmsg net/socket.c:2671 [inline]
       __do_sys_sendmsg net/socket.c:2676 [inline]
       __se_sys_sendmsg net/socket.c:2674 [inline]
       __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2674
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 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+0x546/0x680 block/blk-core.c:461
       blk_mq_alloc_queue block/blk-mq.c:4429 [inline]
       __blk_mq_alloc_disk+0x197/0x390 block/blk-mq.c:4476
       nbd_dev_add+0x499/0xb50 drivers/block/nbd.c:1954
       nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692
       do_one_initcall+0x250/0x8d0 init/main.c:1382
       do_initcall_level+0x104/0x190 init/main.c:1444
       do_initcalls+0x59/0xa0 init/main.c:1460
       kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692
       kernel_init+0x1d/0x1d0 init/main.c:1582
       ret_from_fork+0x51e/0xb90 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:4348 [inline]
       fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4362
       might_alloc include/linux/sched/mm.h:317 [inline]
       slab_pre_alloc_hook mm/slub.c:4489 [inline]
       slab_alloc_node mm/slub.c:4843 [inline]
       kmem_cache_alloc_node_noprof+0x4a/0x690 mm/slub.c:4918
       kmalloc_reserve net/core/skbuff.c:613 [inline]
       __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
       alloc_skb include/linux/skbuff.h:1383 [inline]
       __ip6_append_data+0x2a44/0x3c50 net/ipv6/ip6_output.c:1669
       ip6_append_data+0x10f/0x280 net/ipv6/ip6_output.c:1857
       rawv6_sendmsg+0x12d3/0x18e0 net/ipv6/raw.c:912
       sock_sendmsg_nosec net/socket.c:721 [inline]
       __sock_sendmsg net/socket.c:736 [inline]
       ____sys_sendmsg+0x80a/0x9f0 net/socket.c:2585
       ___sys_sendmsg+0x2a5/0x360 net/socket.c:2639
       __sys_sendmsg net/socket.c:2671 [inline]
       __do_sys_sendmsg net/socket.c:2676 [inline]
       __se_sys_sendmsg net/socket.c:2674 [inline]
       __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2674
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_sock_nested+0x41/0x100 net/core/sock.c:3780
       lock_sock include/net/sock.h:1713 [inline]
       inet_shutdown+0x6a/0x390 net/ipv4/af_inet.c:915
       nbd_mark_nsock_dead+0x2e9/0x560 drivers/block/nbd.c:318
       recv_work+0x1c7f/0x1d90 drivers/block/nbd.c:1021
       process_one_work kernel/workqueue.c:3276 [inline]
       process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
       worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
       kthread+0x388/0x470 kernel/kthread.c:436
       ret_from_fork+0x51e/0xb90 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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:614 [inline]
       __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
       nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
       nbd_queue_rq+0x37b/0x1100 drivers/block/nbd.c:1207
       blk_mq_dispatch_rq_list+0xa70/0x1910 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+0xdcc/0x1600 block/blk-mq-sched.c:307
       blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
       blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386
       blk_mq_dispatch_list+0xd16/0xe10 include/linux/spinlock.h:-1
       blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997
       __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230
       blk_finish_plug block/blk-core.c:1257 [inline]
       __submit_bio+0x28d/0x580 block/blk-core.c:649
       __submit_bio_noacct_mq block/blk-core.c:722 [inline]
       submit_bio_noacct_nocheck+0x2f4/0xa70 block/blk-core.c:753
       submit_bh fs/buffer.c:2826 [inline]
       block_read_full_folio+0x599/0x830 fs/buffer.c:2444
       filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501
       do_read_cache_folio+0x358/0x590 mm/filemap.c:4101
       read_mapping_folio include/linux/pagemap.h:1028 [inline]
       read_part_sector+0xb6/0x2b0 block/partitions/core.c:723
       adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360
       check_partition block/partitions/core.c:142 [inline]
       blk_add_partitions block/partitions/core.c:590 [inline]
       bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694
       blkdev_get_whole+0x380/0x510 block/bdev.c:764
       bdev_open+0x31e/0xd30 block/bdev.c:973
       blkdev_open+0x470/0x610 block/fops.c:697
       do_dentry_open+0x785/0x14e0 fs/open.c:949
       vfs_open+0x3b/0x340 fs/open.c:1081
       do_open fs/namei.c:4671 [inline]
       path_openat+0x2e08/0x3860 fs/namei.c:4830
       do_file_open+0x23e/0x4a0 fs/namei.c:4859
       do_sys_openat2+0x113/0x200 fs/open.c:1366
       do_sys_open fs/open.c:1372 [inline]
       __do_sys_openat fs/open.c:1388 [inline]
       __se_sys_openat fs/open.c:1383 [inline]
       __x64_sys_openat+0x138/0x170 fs/open.c:1383
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x14d/0xf80 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/5839:
 #0: ffff888026c2b358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:961
 #1: ffff8880259ac618 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
 #1: ffff8880259ac618 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
 #1: ffff8880259ac618 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x31f/0x4f0 block/blk-mq.c:2386
 #2: ffff888032d88180 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc6/0x1100 drivers/block/nbd.c:1199

stack backtrace:
CPU: 1 UID: 0 PID: 5839 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:614 [inline]
 __mutex_lock+0x19f/0x1300 kernel/locking/mutex.c:776
 nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
 nbd_queue_rq+0x37b/0x1100 drivers/block/nbd.c:1207
 blk_mq_dispatch_rq_list+0xa70/0x1910 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+0xdcc/0x1600 block/blk-mq-sched.c:307
 blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
 blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386
 blk_mq_dispatch_list+0xd16/0xe10 include/linux/spinlock.h:-1
 blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997
 __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230
 blk_finish_plug block/blk-core.c:1257 [inline]
 __submit_bio+0x28d/0x580 block/blk-core.c:649
 __submit_bio_noacct_mq block/blk-core.c:722 [inline]
 submit_bio_noacct_nocheck+0x2f4/0xa70 block/blk-core.c:753
 submit_bh fs/buffer.c:2826 [inline]
 block_read_full_folio+0x599/0x830 fs/buffer.c:2444
 filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501
 do_read_cache_folio+0x358/0x590 mm/filemap.c:4101
 read_mapping_folio include/linux/pagemap.h:1028 [inline]
 read_part_sector+0xb6/0x2b0 block/partitions/core.c:723
 adfspart_check_ICS+0xa5/0xa40 block/partitions/acorn.c:360
 check_partition block/partitions/core.c:142 [inline]
 blk_add_partitions block/partitions/core.c:590 [inline]
 bdev_disk_changed+0x7ba/0x1550 block/partitions/core.c:694
 blkdev_get_whole+0x380/0x510 block/bdev.c:764
 bdev_open+0x31e/0xd30 block/bdev.c:973
 blkdev_open+0x470/0x610 block/fops.c:697
 do_dentry_open+0x785/0x14e0 fs/open.c:949
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5c374a7407
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:00007ffdef8ae8b0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f5c37b87880 RCX: 00007f5c374a7407
RDX: 00000000000a0800 RSI: 000055876c1a9280 RDI: ffffffffffffff9c
RBP: 000055876c19a910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055876c1b2e00
R13: 000055876c1a8190 R14: 0000000000000000 R15: 000055876c1b2e00
 </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 0x800000 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 0x800000 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 0x800000 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 0x800000 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 0x800000 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 0x800000 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 0x800000 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 0x800000 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 0x800000 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 0x800000 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
block nbd3: Send control failed (result -32)
block nbd3: Request send failed, requeueing
block nbd3: Dead connection, failed to find a fallback
block nbd3: shutting down sockets
ldm_validate_partition_table(): Disk read failed.
Dev nbd3: unable to read RDB block 0
 nbd3: unable to read partition table
ldm_validate_partition_table(): Disk read failed.
Dev nbd3: unable to read RDB block 0
 nbd3: unable to read partition table
block nbd5: Dead connection, failed to find a fallback
block nbd5: shutting down sockets
ldm_validate_partition_table(): Disk read failed.
Dev nbd5: unable to read RDB block 0
 nbd5: unable to read partition table
ldm_validate_partition_table(): Disk read failed.
Dev nbd5: unable to read RDB block 0
 nbd5: unable to read partition table
block nbd7: Send control failed (result -32)
block nbd7: Request send failed, requeueing
ldm_validate_partition_table(): Disk read failed.
Dev nbd7: unable to read RDB block 0
 nbd7: unable to read partition table
ldm_validate_partition_table(): Disk read failed.
Dev nbd7: unable to read RDB block 0
 nbd7: unable to read partition table
block nbd9: Send control failed (result -32)
block nbd9: Request send failed, requeueing
ldm_validate_partition_table(): Disk read failed.
Dev nbd9: unable to read RDB block 0
 nbd9: unable to read partition table
ldm_validate_partition_table(): Disk read failed.
Dev nbd9: unable to read RDB block 0
 nbd9: unable to read partition table
block nbd11: Send control failed (result -32)
block nbd11: Request send failed, requeueing
ldm_validate_partition_table(): Disk read failed.
Dev nbd11: unable to read RDB block 0
 nbd11: unable to read partition table
ldm_validate_partition_table(): Disk read failed.
Dev nbd11: unable to read RDB block 0
 nbd11: unable to read partition table
block nbd13: Send control failed (result -32)
block nbd13: Request send failed, requeueing
block nbd13: Dead connection, failed to find a fallback
block nbd13: shutting down sockets
ldm_validate_partition_table(): Disk read failed.
Dev nbd13: unable to read RDB block 0
 nbd13: unable to read partition table
ldm_validate_partition_table(): Disk read failed.
Dev nbd13: unable to read RDB block 0
 nbd13: unable to read partition table
block nbd15: Send control failed (result -32)
block nbd15: Request send failed, requeueing