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dracut-module-setup: Skip initrd-cleanup and initrd-parse-etc in kdump

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When using multipath devices as the target for kdump, if user_friendly_name
is also specified, devices default to names like "mpath*", e.g., mpatha.
In dracut, we obtain a persistent device name via get_persistent_dev. However,
dracut currently believes using /dev/mapper/mpath* could cause issues, thus
alternatively names are used, here it's /dev/disk/by-uuid/<FS_UUID>.

During the kdump boot progress, the /dev/disk/by-uuid/<FS_UUID> will exist as
soon as one of the path devices exists, but it won't be usable by systemd,
since multipathd will claim that device as a path device. Then multipathd will
get stopped before it can create the multipath device.

Without user_friendly_name, /dev/mapper/<WWID> is considered a persistent
device name, avoiding the issue.

The exit of multipathd is due to two dependencies in the current dracut module
90multipath/multipathd.service, "Before=initrd-cleanup.service" and
"Conflicts=initrd-cleanup.service".

As per man 5 systemd.unit, if A.service has "Conflicts=B.service", starting
B.service will stop A.service.

This is useful during normal boot. However, we will never switch-root after
capturing vmcore in kdump.

We need to ensure that multipathd is not killed due to such dependency issue.
Without modifying multipathd.service, we add ConditionPathExists=!/proc/vmcore
to skip initrd-cleanup.service in kdump. This approach is beneficial as
it avoid the potential termination of other services that conflict with
initrd-cleanup.service. Also skip initrd-parse-etc.service as it will try to
start initrd-cleanup.service. Both of these services are used for switch root,
so they can be safely skipped in kdump.

Suggested-by: Benjamin Marzinski <bmarzins@redhat.com>
Suggested-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Lichen Liu <lichliu@redhat.com>
Reviewed-by: Philipp Rudo <prudo@redhat.com>
This commit is contained in:
Lichen Liu 2024-01-22 15:59:09 +08:00 committed by Coiby Xu
parent 6943de2cdc
commit 468336700d
1 changed files with 9 additions and 0 deletions
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9
dracut-module-setup.sh
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@ -1070,6 +1070,15 @@ install() {
's/\(^[[:space:]]*reserved_memory[[:space:]]*=\)[[:space:]]*[[:digit:]]*/\1 1024/' \ 's/\(^[[:space:]]*reserved_memory[[:space:]]*=\)[[:space:]]*[[:digit:]]*/\1 1024/' \
"${initdir}/etc/lvm/lvm.conf" &> /dev/null "${initdir}/etc/lvm/lvm.conf" &> /dev/null
# Skip initrd-cleanup.service and initrd-parse-etc.service becasue we don't
# need to switch root. Instead of removing them, we use ConditionPathExists
# to check if /proc/vmcore exists to determine if we are in kdump.
sed -i '/\[Unit\]/a ConditionPathExists=!\/proc\/vmcore' \
"${initdir}/${systemdsystemunitdir}/initrd-cleanup.service" &> /dev/null
sed -i '/\[Unit\]/a ConditionPathExists=!\/proc\/vmcore' \
"${initdir}/${systemdsystemunitdir}/initrd-parse-etc.service" &> /dev/null
# Save more memory by dropping switch root capability # Save more memory by dropping switch root capability
dracut_no_switch_root dracut_no_switch_root
} }