Proxmox 6.0.4
Backup Storage - Dir
VM Storage - Thin LVM
Backup type - snapshot

INFO: Starting Backup of VM 115 (qemu)
INFO: Backup started at 2019-08-30 03:31:42
INFO: status = running
INFO: update VM 115: -lock backup
INFO: VM Name: GREEN-6015
INFO: exclude disk 'sata0' 'backup:115/vm-115-disk-0.qcow2' (backup=no)
INFO: include disk 'sata1' 'local-lvm:vm-115-disk-1' 140G
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO: creating archive '/mnt/backup/dump/vzdump-qemu-115-2019_08_30-03_31_42.vma'
ERROR: got timeout
INFO: aborting backup job
ERROR: VM 115 qmp command 'backup-cancel' failed - got timeout
ERROR: Backup of VM 115 failed - got timeout
INFO: Failed at 2019-08-30 03:41:48

в логе dmesg такое:

[337488.297363] INFO: task kvm:2164 blocked for more than 120 seconds.
[337488.297384]       Tainted: P           O      5.0.15-1-pve #1
[337488.297397] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[337488.297414] kvm             D    0  2164      1 0x00000000
[337488.297416] Call Trace:
[337488.297423]  __schedule+0x2d4/0x870
[337488.297424]  schedule+0x2c/0x70
[337488.297427]  jbd2_log_wait_commit+0xaf/0x120
[337488.297430]  ? wait_woken+0x80/0x80
[337488.297431]  jbd2_complete_transaction+0x57/0x90
[337488.297433]  ext4_sync_file+0x3b0/0x400
[337488.297436]  vfs_fsync_range+0x48/0x80
[337488.297438]  ? __fget_light+0x54/0x60
[337488.297439]  do_fsync+0x3d/0x70
[337488.297443]  ? fire_user_return_notifiers+0x3e/0x50
[337488.297444]  __x64_sys_fdatasync+0x17/0x20
[337488.297447]  do_syscall_64+0x5a/0x110
[337488.297449]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[337488.297451] RIP: 0033:0x7fbb64e412e7
[337488.297454] Code: Bad RIP value.
[337488.297455] RSP: 002b:00007fb5815ad780 EFLAGS: 00000293 ORIG_RAX: 000000000000004b
[337488.297456] RAX: ffffffffffffffda RBX: 000000000000000f RCX: 00007fbb64e412e7
[337488.297457] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000000f
[337488.297457] RBP: 00007fbb5806c850 R08: 0000000000000000 R09: 00000000ffffffff
[337488.297457] R10: 00007fb5815ad760 R11: 0000000000000293 R12: 00005617df5b2ef2
[337488.297458] R13: 00007fbb5806c8b8 R14: 00007fbb4da28330 R15: 00005617df5af4c2