[Bug 2112372] Re: Please increase fs.inotify.max_user_instances

[Mario Limonciello]

I don't think we should be increasing max instances to fix this bug.  We
had something similar reported upstream from a bad USB device.

https://github.com/fwupd/fwupd/issues/8712

It was fixed in fwupd 2.0.10 with this change:

https://github.com/fwupd/fwupd/commit/53bd09f66508050ea1d958a09c3db1b4dd4c6778

Would you be able to check if it helps?  Here's a quick primer on how
you can check (without disturbing your current system much).

1. Disable fwupd.service
sudo systemctl stop fwupd.service
sudo systemctl disable fwupd.service
2. Follow this guide to setup the fwupd development env
https://fwupd.github.io/libfwupdplugin/building.html
3. Run the daemon manually from the venv
4. Run the client manually from the venv (in another tab)

If it helps then we can confidently say that this will be fixed on the
next fwupd uprev.

** Bug watch added: github.com/fwupd/fwupd/issues #8712
   https://github.com/fwupd/fwupd/issues/8712

** Changed in: fwupd (Ubuntu)
       Status: New => Triaged

** Also affects: fwupd via
   https://github.com/fwupd/fwupd/issues/8712
   Importance: Unknown
       Status: Unknown

** Changed in: fwupd (Ubuntu)
   Importance: Undecided => Medium

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https://bugs.launchpad.net/bugs/2112372

Title:
  Please increase fs.inotify.max_user_instances

Status in Fwupd:
  Unknown
Status in fwupd package in Ubuntu:
  Triaged
Status in fwupd package in CentOS:
  Unknown

Bug description:
  Hi,

  on my system, with default sysctl parameters, fwupd fails to start
  because of a crash.

  In the journal, I see many error messages such as this one:

  Jun 03 10:16:59 vougeot fwupd[42726]: 08:16:59.639 FuBackend
  failed to create device: failed to probe: failed to open
  /sys/devices/pci0000:00/0000:00:08.3/uevent: Too many open files

  and then:

  Jun 03 10:17:01 vougeot fwupd[42726]: 08:17:01.371 GLib
  Creating pipes for GWakeup: Too many open files

  Finally fwupd crashes:

  Jun 03 10:17:01 vougeot kernel: traps: fwupd[42726] trap int3
  ip:7f8742880f0f sp:7ffd2e9639c0 error:0 in
  libglib-2.0.so.0.8400.1[73f0f,7f874282c000+bd000]

  Here are inotify parameters:

  # sysctl fs.inotify
  fs.inotify.max_queued_events = 16384
  fs.inotify.max_user_instances = 256   # This is already increased from a default of 128
  fs.inotify.max_user_watches = 65536

  Increasing fs.inotify.max_user_instances to 512 fixes the problem.

  Of course, fwupd should also be made more robust and not crash when it
  encounters a system limit.

  Thanks.

  ProblemType: Bug
  DistroRelease: Ubuntu 25.04
  Package: fwupd 2.0.7-1
  Uname: Linux 6.14.9-zabbly+ x86_64
  ApportVersion: 2.32.0-0ubuntu5.1
  Architecture: amd64
  CasperMD5CheckResult: unknown
  CurrentDesktop: KDE
  Date: Tue Jun  3 11:30:54 2025
  SourcePackage: fwupd
  UpgradeStatus: No upgrade log present (probably fresh install)
  modified.conffile..etc.fwupd.fwupd.conf: [inaccessible: [Errno 13] Permission denied: '/etc/fwupd/fwupd.conf']

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