Out of memory error during git push

Hi all

I'm experiencing the following error while pushing a git repo (home
directory) to my QNAP TS-210:

user@mypc:~$ git push origin master
Counting objects: 12532, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (8974/8974), done.
fatal: Out of memory, malloc failed, 986.06 MiB | 1.65 MiB/s
error: pack-objects died of signal 13
error: pack-objects died with strange error
error: failed to push some refs to
'ssh://nas//share/MD0_DATA/user/repositories/backup.mypc'

I've searched the internet and found suggestions to try to repack with
lower values for 'depth', 'window' and 'windowMemory'. I used 3, 3, 50
respectively, but a push after the repack command resulted in the same
error.

I tried git fsck which reported a few dangling blobs only and I got the
same error again during the next push.

I watched /proc/meminfo and /proc/swaps on the NAS while pushing and saw
that there are always 20-50MB of free RAM and that from 512MB swap space
only about 180MB are used.

What else can I try to successfully push my repo to my NAS?

Thanks for your help,
Tom