This bug was fixed in the package linux-kvm - 5.8.0-1016.18
---------------
linux-kvm (5.8.0-1016.18) groovy; urgency=medium
* groovy/linux-kvm: 5.8.0-1016.18 -proposed tracker (LP: #1911344)
* CONFIG_BASE_SMALL=1 restricts pid space, which conflicts with systemd
default sysctl (LP: #1866149)
- [Config]: set CONFIG_BASE_FULL
* Missing module nfsv4 in linux-kvm (LP: #1907266)
- [Config] kvm: Enable NFSv4
[ Ubuntu: 5.8.0-39.44 ]
* groovy/linux: 5.8.0-39.44 -proposed tracker (LP: #1911350)
* overlay: permission regression in 5.4.0-51.56 due to patches related to
CVE-2020-16120 (LP: #1900141)
- ovl: do not fail because of O_NOATIME
[ Ubuntu: 5.8.0-38.43 ]
* groovy/linux: 5.8.0-38.43 -proposed tracker (LP: #1911143)
* CVE-2020-28374
- SAUCE: target: fix XCOPY NAA identifier lookup
* Packaging resync (LP: #1786013)
- update dkms package versions
[ Ubuntu: 5.8.0-36.40 ]
* debian/scripts/file-downloader does not handle positive failures correctly
(LP: #1878897)
- [Packaging] file-downloader not handling positive failures correctly
[ Ubuntu: 5.8.0-35.39 ]
* Packaging resync (LP: #1786013)
- update dkms package versions
* CVE-2021-1052 // CVE-2021-1053
- [Packaging] NVIDIA -- Add the NVIDIA 460 driver
-- Kelsey Skunberg <kelsey.skunb...@canonical.com> Thu, 14 Jan 2021
16:31:26 -0700
** Changed in: linux-kvm (Ubuntu Xenial)
Status: Fix Committed => Fix Released
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https://bugs.launchpad.net/bugs/1866149
Title:
CONFIG_BASE_SMALL=1 restricts pid space, which conflicts with systemd
default sysctl
Status in linux package in Ubuntu:
Invalid
Status in linux-kvm package in Ubuntu:
Incomplete
Status in linux source package in Xenial:
Invalid
Status in linux-kvm source package in Xenial:
Fix Released
Status in linux source package in Bionic:
Invalid
Status in linux-kvm source package in Bionic:
Fix Released
Status in linux source package in Focal:
Invalid
Status in linux-kvm source package in Focal:
Fix Released
Status in linux source package in Groovy:
Invalid
Status in linux-kvm source package in Groovy:
Fix Released
Bug description:
[Impact]
systemd-systemctl will fail to set kernel.pid_max, leading to a degraded boot.
[Fix]
Set CONFIG_BASE_FULL=y, CONFIG_BASE_SMALL=0.
[Test case]
Write 419304 to /proc/sys/kernel/pid_max.
[Potential regression]
Boot time may be affected.
====================================================================
I'm not completely sure which package to log this against.
I'm running the kvm focal minimal cloud image from 20200302. I noticed
on boot that there was an error complaining that systemd-systemctl
couldn't update pid_max to the value it wanted:
systemd-sysctl[117]: Couldn't write '4194304' to 'kernel/pid_max':
Invalid argument
Digging into it a bit more, this comes from /usr/lib/sysctl.d/50-pid-max.conf:
# Bump the numeric PID range to its maximum of 2^22 (from the in-kernel
default
# of 2^16), to make PID collisions less likely.
kernel.pid_max = 4194304
However, the linux-image-kvm kernel is compiled with
CONFIG_BASE_SMALL=1
and this triggers the following code in include/linux/threads.h
#define PID_MAX_LIMIT (CONFIG_BASE_SMALL ? PAGE_SIZE * 8 : \
(sizeof(long) > 4 ? 4 * 1024 * 1024 : PID_MAX_DEFAULT))
which means that if CONFIG_BASE_SMALL is set we get a maximum limit of
PAGE_SIZE * 8, which on x86 would be 32768.
As a workaround I can override it with a file in /etc/sysctl.d/ but
this shouldn't be needed.
I really don't know if CONFIG_BASE_SMALL makes any sense on x86 cloud
images, they really aren't small machines in the scheme of things!
Cheers
David
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