Hi Chris,

I stood up a Jammy VM, and tried with and without apparmor=0 on the
kernel command line, for a few hours at a time.

The /proc/slabinfo for kmalloc-2k and /proc/meminfo for unreclaimable
slabs were stable and did not grow, so it must be related to your
workload.

What sort of workloads are running on your servers?

If you stand up a fresh VM and minimally configure it, can you still see
the kernel memory leak? Or do you need your workload to provoke it?

If you do have a set of commands to reproduce the issue, please list
them here.

Thanks,
Matthew

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You received this bug notification because you are a member of Kernel
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https://bugs.launchpad.net/bugs/1987430

Title:
  Ubuntu 22.04 kernel 5.15.0-46-generic leaks kernel memory in
  kmalloc-2k slabs

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  Since updating to kernel 5.15.0-46-generic (package version
  5.15.0-46.49), all of our Ubuntu 22.04 LTS servers are leaking kernel
  memory; our first server with 8 GB of RAM just fatally OOMed, causing
  us to detect this. Inspection of OOM reports, /proc/meminfo, and
  /proc/slabinfo says that it's mostly going to unreclaimable kmalloc-2k
  slabs:

          Aug 23 12:51:11 cluster kernel: [361299.864757] Unreclaimable slab 
info:
          Aug 23 12:51:11 cluster kernel: [361299.864757] Name                  
    Used          Total
          [...]
          Aug 23 12:51:11 cluster kernel: [361299.864924] kmalloc-2k           
6676584KB    6676596KB

  Most of our machines appear to be leaking slab memory at a rate of
  around 20 to 40 Mbytes/hour, with some machines leaking much faster;
  the champions are leaking kernel memory at 145 Mbytes/hour and 237
  Mbytes/hour.

  We aren't running any proprietary kernel modules and our only unusual
  kernel configuration is that we've disabled AppArmor with 'apparmor=0'
  on the kernel command line.

  /proc/version_signature:
  Ubuntu 5.15.0-46.49-generic 5.15.39

  Full kernel command line from the Dell R240 system that fatally OOMd:
  BOOT_IMAGE=/boot/vmlinuz-5.15.0-46-generic 
root=UUID=3165564f-a2dd-4b39-935b-114f3e23ff54 ro console=ttyS0,115200 
console=tty0 apparmor=0

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