Kernel bloat

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davo4prog
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Kernel bloat

Post by davo4prog » Tue Mar 06, 2018 7:30 am

I used to have an 8 gig partition for root (an another larger for home). This was adequate for the past 20 odd years. I increased that to 15 gig a year or so ago and it has been running out of space. The constant updating of Kernels is what is doing it. So apart from cleaning our /var/cache/apt/archives from time to time I started deleting old versions of vmlinuz in /boot. Recently I ran a check for large files and found /lib/modules was big, deleting old versions here cleared up 4 gig. Point of this post is that the frequent release of kernel versions, virtually every time I do an update, is bloating the system because they don't get deleted.

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Moem
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Re: Kernel bloat

Post by Moem » Tue Mar 06, 2018 7:56 am

So delete them. It's a normal part of OS maintenance and can be done through the Update Manager.
We're getting a lot more kernel updates recently because of the patches needed to help protect us from Spectre and Meltdown, so it's for a good cause.

Is there anything you wanted to ask with regards to this?

Mod note: moving this post because it's not about software or applications.
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If your issue is solved, kindly indicate that by editing the first post in the topic, and adding [SOLVED] to the title. Thanks!

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kc1di
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Re: Kernel bloat

Post by kc1di » Tue Mar 06, 2018 7:58 am

Kernels become bloated because users keep asking for it to do more and more. - you can keep your disc usage in check by removing unused kernels. I usually make it a habit of keep one older kernel and the one I'm currently using. Just in case I need to go back because of hardware or such. But once I'm satisfied that the new kernel is working properly I may even delete that older one.
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Cosmo.
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Re: Kernel bloat

Post by Cosmo. » Tue Mar 06, 2018 8:34 am

There is indeed a problem with the amount of kernels, which can fill a drive after some time. Newbie users do not necessarily know, that in difference to all other packages, where an updated package replaces the previous one, new kernels get added to the system. If there should be a way to make it easier to remove not needed kernels, is an open questions, which starts with the question, which kernels are really not needed for an easy way to revert in case of problems. But as the update manager is permanently adding new kernels it should have an option to display a message, if a certain number of installed kernels (possibly configurable in the preferences) have been reached. This could e. g. be done with a colored bar at the top of the update manager, similar to the bar which advises to switch to a mirror.

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Pjotr
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Re: Kernel bloat

Post by Pjotr » Tue Mar 06, 2018 9:27 am

Restore normality with this kernel cleaning method:
https://sites.google.com/site/easylinux ... one-stroke
(item 8.1, right column)

As I've already tried to communicate to the devs: this is a feature that should be built into Update Manager, imo.....
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davo4prog
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Re: Kernel bloat

Post by davo4prog » Tue Mar 06, 2018 6:35 pm

Thanks for the help. Much better than manually deleting them.

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majpooper
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Re: Kernel bloat

Post by majpooper » Thu Mar 08, 2018 12:05 am

As a rule of thumb I always keep one or two prior kernels - just in case. However every time I download a new kernel and do a restart I then remove the oldest kernel via the update manager. I have yet to have to go back to a prior kernel - but one never knows . . . Anyway this keeps the number of kernels to a manageable level.

davo4prog
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Re: Kernel bloat

Post by davo4prog » Fri Mar 09, 2018 8:31 am

Discussing this in https://www.linuxquestions.org/question ... ost5829000


Originally Posted by chrism01
ok - also in /etc/yum.conf we have
Code:

Code: Select all

installonly_limit=3
which automatically limits installed kernels to last ie newest 3.
It auto purges oldest when you install a '4th', so you never actually need to run yum manually to reduce kernels :)
Hi Thanks,

Mint does not use YUM, in looking in /etc I did find a generated file /etc/apt/apt.conf.d/01autoremove-kernels which is created by
/etc/kernel/postinst.d/apt-auto-removal
There was mention on #lines about keeping 4 kernels, but this hasn't been my experience, My linux progaming skills extend to simple scripts, however I will pass this over to Mint Forums. Thanks indeed, the answer is there somewhere.
Last edited by Moem on Fri Mar 09, 2018 8:34 am, edited 1 time in total.
Reason: Some improvements in formatting.

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kc1di
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Re: Kernel bloat

Post by kc1di » Fri Mar 09, 2018 9:12 am

This ubuntu wiki page (Though quite old now) addresses the problems involved in auto removal of kernels. And it's the same rational used by Mint, I don't believe this has changed over the years.
https://wiki.ubuntu.com/KernelTeam/removing-old-kernels
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davo4prog
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Re: Kernel bloat

Post by davo4prog » Sat Mar 10, 2018 6:40 am

This is /etc/apt/apt.conf.d/01autoremove-kernels

Code: Select all

// DO NOT EDIT! File autogenerated by /etc/kernel/postinst.d/apt-auto-removal
APT::NeverAutoRemove
{
   "^linux-image-4\.10\.0-38-generic$";
   "^linux-image-4\.13\.0-36-generic$";
   "^linux-headers-4\.10\.0-38-generic$";
   "^linux-headers-4\.13\.0-36-generic$";
   "^linux-image-extra-4\.10\.0-38-generic$";
   "^linux-image-extra-4\.13\.0-36-generic$";
   "^linux-signed-image-4\.10\.0-38-generic$";
   "^linux-signed-image-4\.13\.0-36-generic$";
   "^kfreebsd-image-4\.10\.0-38-generic$";
   "^kfreebsd-image-4\.13\.0-36-generic$";
   "^kfreebsd-headers-4\.10\.0-38-generic$";
   "^kfreebsd-headers-4\.13\.0-36-generic$";
   "^gnumach-image-4\.10\.0-38-generic$";
   "^gnumach-image-4\.13\.0-36-generic$";
   "^.*-modules-4\.10\.0-38-generic$";
   "^.*-modules-4\.13\.0-36-generic$";
   "^.*-kernel-4\.10\.0-38-generic$";
   "^.*-kernel-4\.13\.0-36-generic$";
   "^linux-backports-modules-.*-4\.10\.0-38-generic$";
   "^linux-backports-modules-.*-4\.13\.0-36-generic$";
   "^linux-tools-4\.10\.0-38-generic$";
   "^linux-tools-4\.13\.0-36-generic$";
};
/* Debug information:
# dpkg list:
ii  linux-image-4.10.0-38-generic               4.10.0-38.42~16.04.1                         amd64        Linux kernel image for version 4.10.0 on 64 bit x86 SMP
ii  linux-image-4.13.0-36-generic               4.13.0-36.40~16.04.1                         amd64        Linux kernel image for version 4.13.0 on 64 bit x86 SMP
ii  linux-image-extra-4.10.0-38-generic         4.10.0-38.42~16.04.1                         amd64        Linux kernel extra modules for version 4.10.0 on 64 bit x86 SMP
iF  linux-image-extra-4.13.0-36-generic         4.13.0-36.40~16.04.1                         amd64        Linux kernel extra modules for version 4.13.0 on 64 bit x86 SMP
# list of installed kernel packages:
4.10.0-38-generic 4.10.0-38.42~16.04.1
4.13.0-36-generic 4.13.0-36.40~16.04.1
# list of different kernel versions:
4.13.0-36.40~16.04.1
4.10.0-38.42~16.04.1
# Installing kernel: 4.13.0-36.40~16.04.1 (4.13.0-36-generic)
# Running kernel: 4.10.0-38.42~16.04.1 (4.10.0-38-generic)
# Last kernel: 4.13.0-36.40~16.04.1
# Previous kernel: 4.10.0-38.42~16.04.1
# Kernel versions list to keep:
4.10.0-38.42~16.04.1
This is /etc/kernel/postinst.d/apt-auto-removal

Code: Select all

#!/bin/sh
set -e
# Mark as not-for-autoremoval those kernel packages that are:
#  - the currently booted version
#  - the kernel version we've been called for
#  - the latest kernel version (as determined by debian version number)
#  - the second-latest kernel version
#
# In the common case this results in two kernels saved (booted into the
# second-latest kernel, we install the latest kernel in an upgrade), but
# can save up to four. Kernel refers here to a distinct release, which can
# potentially be installed in multiple flavours counting as one kernel.

eval $(apt-config shell APT_CONF_D Dir::Etc::parts/d)
test -n "${APT_CONF_D}" || APT_CONF_D="/etc/apt/apt.conf.d"
config_file="${APT_CONF_D}/01autoremove-kernels"

eval $(apt-config shell DPKG Dir::bin::dpkg/f)
test -n "$DPKG" || DPKG="/usr/bin/dpkg"

list="$("${DPKG}" -l | awk '/^[ih][^nc][ ]+(linux|kfreebsd|gnumach)-image-[0-9]+\./ && $2 !~ /-dbg(:.*)?$/ && $2 !~ /-dbgsym(:.*)?$/ { print $2,$3; }' \
   | sed -e 's#^\(linux\|kfreebsd\|gnumach\)-image-##' -e 's#:[^:]\+ # #')"
debverlist="$(echo "$list" | cut -d' ' -f 2 | sort --unique --reverse --version-sort)"

if [ -n "$1" ]; then
	installed_version="$(echo "$list" | awk "\$1 == \"$1\" { print \$2;exit; }")"
fi
unamer="$(uname -r)"
if [ -n "$unamer" ]; then
	running_version="$(echo "$list" | awk "\$1 == \"$unamer\" { print \$2;exit; }")"
fi
latest_version="$(echo "$debverlist" | sed -n 1p)"
previous_version="$(echo "$debverlist" | sed -n 2p)"

debkernels="$(echo "$latest_version
$installed_version
$running_version
$previous_version" | sort -u | sed -e '/^$/ d')"
kernels="$( (echo "$1
$unamer"; for deb in $debkernels; do echo "$list" | awk "\$2 == \"$deb\" { print \$1; }"; done; ) \
   | sed -e 's#\([\.\+]\)#\\\1#g' -e '/^$/ d' | sort -u)"

generateconfig() {
	cat <<EOF
// DO NOT EDIT! File autogenerated by $0
APT::NeverAutoRemove
{
EOF
	for package in $(apt-config dump --no-empty --format '%v%n' 'APT::VersionedKernelPackages'); do
		for kernel in $kernels; do
			echo "   \"^${package}-${kernel}$\";"
		done
	done
	echo '};'
	if [ "${APT_AUTO_REMOVAL_KERNELS_DEBUG:-true}" = 'true' ]; then
		cat <<EOF
/* Debug information:
# dpkg list:
$(dpkg -l | grep '\(linux\|kfreebsd\|gnumach\)-image-')
# list of installed kernel packages:
$list
# list of different kernel versions:
$debverlist
# Installing kernel: $installed_version ($1)
# Running kernel: $running_version ($unamer)
# Last kernel: $latest_version
# Previous kernel: $previous_version
# Kernel versions list to keep:
$debkernels
# Kernel packages (version part) to protect:
$kernels
*/
EOF
	fi
}
generateconfig "$@" > "${config_file}.dpkg-new"
mv -f "${config_file}.dpkg-new" "$config_file"
chmod 444 "$config_file"
Last edited by Moem on Sat Mar 10, 2018 7:27 am, edited 1 time in total.
Reason: Please use the code tags for long code and terminal outputs.

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