High Shared memory usage


New Member
Feb 4, 2021
TL;DR : I'm trying to understand what the shared memory part of free means in proxmox

I've recently created a new container on a host that reports a 60% memory usage
I've got oom-kill that gets invoked because my RAM usage looks like that :

               total        used        free      shared  buff/cache   available
Mem:           31Gi        20Gi       194Mi        10Gi        10Gi       133Mi
Swap:            0B          0B          0B

So I understand that there is no free memory, but I'm only using 20 of the 32GB of memory that I have, so I would have guessed that it would be cache, that can be cleared when more memory is needed, and indeed, before running my new container, there is 11-12GiB of cache. When I run it, it drops to 10GiB, as shown on the output shown before, it seems that some cache is cleared, but it stops at 10GiB

So to me, the culprit is the shared memory, but I don't understand what is in that shared memory.
For info, in total I have 400MiB in tmpfs, and 140MiB in KSM Sharing, for a total of 540MiB of shared mem accounted for
The host contains mostly Containers, with only one VM that has 2GiB of RAM.

root@mimas:/home/me# df -h | grep tmpfs
tmpfs                               3.2G  330M  2.9G  11% /run
tmpfs                                16G   79M   16G   1% /dev/shm
tmpfs                               5.0M     0  5.0M   0% /run/lock
tmpfs                                16G     0   16G   0% /sys/fs/cgroup
tmpfs                               3.2G     0  3.2G   0% /run/user/1000

Feel free to ask any questions if anything is not clear
Kind regards
Last edited:
OK so turns out I forgot to account for the tmpfs in the containers themselves, which was taken by the journal, put the journl in persistent storage and that solved the issue


The Proxmox community has been around for many years and offers help and support for Proxmox VE, Proxmox Backup Server, and Proxmox Mail Gateway.
We think our community is one of the best thanks to people like you!

Get your subscription!

The Proxmox team works very hard to make sure you are running the best software and getting stable updates and security enhancements, as well as quick enterprise support. Tens of thousands of happy customers have a Proxmox subscription. Get yours easily in our online shop.

Buy now!