Stories
Slash Boxes
Comments

SoylentNews is people

posted by Fnord666 on Sunday May 10 2020, @06:47PM   Printer-friendly
from the stormy-weather dept.

System adminsitrator Chris Siebenmann has found Modern versions of systemd can cause an unmount storm during shutdowns:

One of my discoveries about Ubuntu 20.04 is that my test machine can trigger the kernel's out of memory killing during shutdown. My test virtual machine has 4 GB of RAM and 1 GB of swap, but it also has 347 NFS[*] mounts, and after some investigation, what appears to be happening is that in the 20.04 version of systemd (systemd 245 plus whatever changes Ubuntu has made), systemd now seems to try to run umount for all of those filesystems all at once (which also starts a umount.nfs process for each one). On 20.04, this is apparently enough to OOM[**] my test machine.

[...] Unfortunately, so far I haven't found a way to control this in systemd. There appears to be no way to set limits on how many unmounts systemd will try to do at once (or in general how many units it will try to stop at once, even if that requires running programs). Nor can we readily modify the mount units, because all of our NFS mounts are done through shell scripts by directly calling mount; they don't exist in /etc/fstab or as actual .mount units.

[*] NFS: Network File System
[**] OOM Out of memory.

We've been here before and there is certainly more where that came from.

Previously:
(2020) Linux Home Directory Management is About to Undergo Major Change
(2019) System Down: A systemd-journald Exploit
(2017) Savaged by Systemd
(2017) Linux systemd Gives Root Privileges to Invalid Usernames
(2016) Systemd Crashing Bug
(2015) tmux Coders Asked to Add Special Code for systemd
(2016) SystemD Mounts EFI pseudo-fs RW, Facilitates Permanently Bricking Laptops, Closes Bug Invalid
(2015) A Technical Critique of Systemd
(2014) Devuan Developers Can Be Reached Via vua@debianfork.org
(2014) Systemd-resolved Subject to Cache Poisoning


Original Submission

 
This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 5, Informative) by NCommander on Sunday May 10 2020, @07:53PM (3 children)

    by NCommander (2) Subscriber Badge <michael@casadevall.pro> on Sunday May 10 2020, @07:53PM (#992512) Homepage Journal

    The Technical Committee vote is a serious sore point for me, but I can't go into details as most of it was on debian-private. I can't blame Canonical for switching to systemd when Debian did due to the burden it would have caused, but I put more of the blame on Red Hat who have a long history of shoving shit down the communities throat and forcing people to accept it.

    Red Hat was the reason we had to put up with Ulrich Drepper and the utter nightmare of glibc development until he was forked around with eglibc.

    Disclaimer: I was employed by Canonical at the time, and was a Debian Developer.

    --
    Still always moving
    Starting Score:    1  point
    Moderation   +4  
       Insightful=1, Interesting=1, Informative=2, Total=4
    Extra 'Informative' Modifier   0  
    Karma-Bonus Modifier   +1  

    Total Score:   5  
  • (Score: 0) by Anonymous Coward on Monday May 11 2020, @12:52AM

    by Anonymous Coward on Monday May 11 2020, @12:52AM (#992580)

    Do you recommend an inquiry?

  • (Score: 2, Interesting) by Anonymous Coward on Monday May 11 2020, @09:16PM

    by Anonymous Coward on Monday May 11 2020, @09:16PM (#993085)

    If Debian forgot one of the main points to exist was caring about their users, maybe it is time for some whistleblowing. Not you, just dropping the idea.

    Or the more polite enquire suggested above. But I guess transparency and accountability are just words in the dictionary, not to be applied in real world.

  • (Score: 1, Informative) by Anonymous Coward on Monday May 11 2020, @09:52PM

    by Anonymous Coward on Monday May 11 2020, @09:52PM (#993097)

    Thanks for the veiled insight. Consolations.