** Also affects: linux-meta-hwe-6.5 (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2041668
Title:
Memory leak in 23.10 kernel (6.5.0-10)
Status in linux package in Ubuntu:
Confirmed
Status in linux-meta package in Ubuntu:
Confirmed
Status in linux-meta-hwe-6.5 package in Ubuntu:
New
Bug description:
There appears to be a memory 'leak' in the kernel of the latest Ubuntu release
(Mantic Minotaur, kernel version 6.5.0-10). I put 'leak' in quotes because
this
memory appears to be allocated but never used. The kernel's memory
over-commit
mechanism seems to prevent this leak from manifesting in OOM killer triggers
or
other failures.
The primary symptom is a steady increase in the value reported as
'Committed_AS'
in '/proc/meminfo'. The other memory stats reported there remain reasonable,
though.
I've observed this problem on a fairly diverse set of machines (both VMs and
physical machines) with a variety of workloads. Busier machines seem to have
a
faster leak rate. I've tried to narrow down the issue by rebooting into
single
user mode, killing all userspace processes (except the systemd processes) and
removing as many kernel models as possible. The problem continues in that
state. I didn't see any obvious culprits in /proc/slabinfo nor
/proc/vmallocinfo.
So far, the only way I've been able to remediate this issue is to reboot back
into the Lunar Lobster kernel (6.2.0-35). I think this fact alone rules out
any
triggers that may be part of the 23.10 userspace environment.
I've attached the generic debug info requested by this component's bug
template
from an example machine. Please let me know if there is any more information I
can provide. It seems to be pretty trivial to reproduce though, and I'm
guessing it has not been reported yet because the leak doesn't actually
manifest
in an out-of-memory situation. At least, I haven't observed that yet. The
worst case I've observed was 150 GB of memory committed on a machine with 16
GB
of physical RAM after about 24 hours. Moving back to the previous kernel
version, the committed memory statistic holds fairly steady around 7 GB on
that
machine and workload.
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