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This bug was initially created as a copy of Bug #1748051
I am copying this bug because: it may affect RHEL8 as well
Description of problem:
The /lib/udev/rules.d/40-redhat.rules file defines the following rules for "memory" subsystem:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
# Memory hotadd request
SUBSYSTEM!="memory", GOTO="memory_hotplug_end"
ACTION!="add", GOTO="memory_hotplug_end"
PROGRAM="/bin/uname -p", RESULT=="s390*", GOTO="memory_hotplug_end"
PROGRAM="/bin/uname -p", RESULT=="ppc64*", GOTO="memory_hotplug_end"
ENV{.state}="online"
PROGRAM="/bin/systemd-detect-virt", RESULT=="none", ENV{.state}="online_movable"
ATTR{state}=="offline", ATTR{state}="$env{.state}"
LABEL="memory_hotplug_end"
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
On system that have many Memory devices (in some cases, I can see up to 1000 or 12000 memory devices!!!), these rules will spawn tons of "uname -p" / "systemd-detect-virt" processes which will kill the system.
This issue affects multiple packages as well, for example trace-cmd ("/lib/udev/rules.d/98-trace-cmd.rules") and kexec-tools ("/lib/udev/rules.d/98-kexec.rules").
Version-Release number of selected component (if applicable):
systemd-udev-239-17.el8
How reproducible:
Always
Steps to Reproduce:
1. Enable debugging in udev: "udev.log-priority=debug" while booting
2. Check the number of times a command executed
# journalctl -b | egrep '(PROGRAM|RUN)' | cut -f2- -d"'" | sort | uniq -c | sort -nr
Actual results:
127 kmod load $env{MODALIAS}' /usr/lib/udev/rules.d/80-drivers.rules:5
32 /bin/uname -p' /usr/lib/udev/rules.d/40-redhat.rules:9
32 /bin/uname -p' /usr/lib/udev/rules.d/40-redhat.rules:10
32 /bin/systemd-detect-virt' /usr/lib/udev/rules.d/40-redhat.rules:13
...
Expected results:
1 call to "systemd-detect-virt"
1 call to "uname -p", not 64 calls
Additional info:
This was observed on a system with 16 memory devices (2GB VM with 1 CPU).
Additionally, for some reason, rules execute twice as much as on RHEL7 for same number of memory devices.
On large physical systems, it can be just crazy.