O dispositivo raiz tem 2,9 GB de espaço livre, mas gera erros completos no disco

Question

Título explica tudo, aqui está uma saída do console abaixo para ilustrar o problema. Consegui contornar isso apagando os pacotes antigos que me davam 4.6GB grátis, mas eu queria colocar essa questão aqui por curiosidade, já que tenho trabalhado com ambientes Unix / Linux por mais de uma década agora e nunca vi nada parecido com isso, nem por onde começar a solucionar o problema. Não faz nenhum sentido.

ubuntu@ip-172-31-29-34:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            487M     0  487M   0% /dev
tmpfs           100M  3.0M   97M   4% /run
/dev/xvda1      7.8G  4.6G  2.9G  62% /
tmpfs           496M     0  496M   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           496M     0  496M   0% /sys/fs/cgroup
tmpfs           100M     0  100M   0% /run/user/1000
ubuntu@ip-172-31-29-34:~$ sudo apt-get -f install
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
  linux-headers-4.4.0-65 linux-headers-4.4.0-65-generic linux-headers-4.4.0-66 linux-headers-4.4.0-66-generic linux-headers-4.4.0-70 linux-headers-4.4.0-70-generic
  linux-headers-4.4.0-71 linux-headers-4.4.0-71-generic linux-headers-4.4.0-72 linux-headers-4.4.0-72-generic linux-headers-4.4.0-75 linux-headers-4.4.0-75-generic
  linux-headers-4.4.0-78 linux-headers-4.4.0-78-generic linux-headers-4.4.0-79 linux-headers-4.4.0-79-generic linux-headers-4.4.0-81 linux-headers-4.4.0-81-generic
  linux-headers-4.4.0-83 linux-headers-4.4.0-83-generic linux-headers-4.4.0-87 linux-headers-4.4.0-87-generic linux-image-4.4.0-65-generic
  linux-image-4.4.0-66-generic linux-image-4.4.0-70-generic linux-image-4.4.0-71-generic linux-image-4.4.0-72-generic linux-image-4.4.0-75-generic
  linux-image-4.4.0-78-generic linux-image-4.4.0-79-generic linux-image-4.4.0-81-generic linux-image-4.4.0-83-generic linux-image-4.4.0-87-generic
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  linux-headers-4.4.0-92
The following NEW packages will be installed:
  linux-headers-4.4.0-92
0 upgraded, 1 newly installed, 0 to remove and 149 not upgraded.
7 not fully installed or removed.
Need to get 0 B/9,876 kB of archives.
After this operation, 70.6 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
(Reading database ... 429900 files and directories currently installed.)
Preparing to unpack .../linux-headers-4.4.0-92_4.4.0-92.115_all.deb ...
Unpacking linux-headers-4.4.0-92 (4.4.0-92.115) ...
dpkg: error processing archive /var/cache/apt/archives/linux-headers-4.4.0-92_4.4.0-92.115_all.deb (--unpack):
 error creating directory './usr/src/linux-headers-4.4.0-92/tools/lib/bpf': No space left on device
No apport report written because the error message indicates a disk full error
                                                                              dpkg-deb: error: subprocess paste was killed by signal (Broken pipe)
Errors were encountered while processing:
 /var/cache/apt/archives/linux-headers-4.4.0-92_4.4.0-92.115_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)