Preloaded disposables get created with weird amounts of memory

[Atrate]

How to file a helpful issue

Qubes OS release

r4.3-rc1

Brief summary

When preloading disposables, they get created with weird amounts of memory. They still do work, it's just this may be a symptom of something else going on?

Initial memory for the disposable template is set to 512MB here, MAXMEM is 3G.

Steps to reproduce

1. Have preloaded disposables.

Expected behavior

All of them use the same amount of memory (e.g. the initial memory assigned to the dvm template).

Actual behavior

See screenshot.

Additional information

By the way, I'm very happy to see that they take up so little memory when paused, I was afraid they'd take up MAXMEM memory, which would prohibit many people from having several disposables preloaded.

[ben-grande]

Before pause, qmemman attempts to set the domain memory to an value received from an internal algorithm called pref_mem. The client qube might be slow to reply or its preferred mem might be something different than the initial qube memory (memory property).

In the case of 0.4 and 0.5, it is expected, yes, even if it is a little bit lower than the initial memory.

On the 0.8 GB case, is a bit out of the ordinary because I haven't encountered the pause with more memory than the initial one. The initial memory is in MiB, so 512 MiB is 0.53 GB. 0.8GB/0.53 is 1.5, so it was paused with 50% more than the initial memory, which is not horrible, ideally, it would never happen.

I didn't update to rc1 yet.

1. What template are you using? Debian (12, 13), Fedora (41, 42), Whonix or Kicksecure 17?
2. Did you install something in the template before testing preloads?
3. How much RAM your system has?
4. Did you have many other qubes running also? If yes, how many?
5. Are you using LVM or something else?
6. Now debugging: 1. Set the feature to 0
   1. Watch the qubesd journal: sudo journalctl -fu qubesd -o cat | grep -v pam_unix, pay attention for WARNING log level
   2. Set the feature value to 4 again and check with which memory the qube was paused
   3. Post the qubesd logs here.

If the steps above are not enough to show the issue:

1. Shutdown all non-related qubes, will make logs shorter to read and not leak much info.
2. Change log-level in /etc/qubes/qmemman.conf to 10 (debug)
3. Restart qmemman: systemctl restart qubes-qmemman
4. Watch the qmemman logs: sudo journalctl -fu qubes-qmemman -o cat. It will be very very long. Post with details HTML tag.

By the way, I'm very happy to see that they take up so little memory when paused, I was afraid they'd take up MAXMEM memory, which would prohibit many people from having several disposables preloaded.

It was like that until very recently, not anymore :)

[Atrate]

1. Fedora 42
2. Yes, many things, as I upgraded in-place
3. 64G
4. Yes, over 10. I think that the 800 MB thing has happened when launching many qubes at once, maybe xen-balloon managed to kick in before the qube got paused?
5. btrfs

As for debugging, if you say that the memory being lower than initial memory is expected, I'll take that. When it comes to the 0.8 GB case, I'll try to reproduce it, but it doesn't happen too often.

[ben-grande]

2. Yes, many things, as I upgraded in-place
3. 64G
4. Yes, over 10. I think that the 800 MB thing has happened when launching many qubes at once, maybe xen-balloon managed to kick in before the qube got paused?
5. btrfs

As for debugging, if you say that the memory being lower than initial memory is expected, I'll take that. When it comes to the 0.8 GB case, I'll try to reproduce it, but it doesn't happen too often.

I have preloaded 10 at once on a 32 GB system without them pausing with more memory than necessary. Still, I believe that when multiple qubes are launched at once, it may impact the memory that the qube was paused with.

About pausing with less memory than the initial memory, I have qubes paused with 327 MiB when the initial memory is 400 MiB. Not all of them emit the warning WARNING: Failed to set memoy in qubesd journal. If you see this error, find the qube that emitted this warning and report with how much memory it was paused with. qui-domains might show a more precise info in MiB than xl top can in GB.

[ben-grande]

I have encountered this only after suspend, qubes may be paused with more memory than the initial one. I have 400 MiB initial, qube paused with 975 MiB. Qubesd reports that it failed to set memory. Didn't investigate qmemman yet.

---

It appears to be alleviated after restarting qubes-qmemman..., but still pausing sometimes with more memory than needed.

[ben-grande]

@Atrate Can you confirm that this only happens after you have suspended your machine and not before?

[Atrate]

@Atrate Can you confirm that this only happens after you have suspended your machine and not before?

I do not use suspend, so it's either the same thing triggered by two different things, or something unrelated.