From 9cc6ee46e0083bc36b53d19e14fb637f7a1542dd Mon Sep 17 00:00:00 2001
From: Alexander Graf <graf@amazon.com>
Date: Thu, 9 Jun 2022 16:20:43 +0200
Subject: [PATCH] pstore: Run after modules are loaded

The systemd-pstore service takes pstore files on boot and transfers them
to disk. It only does it once on boot and only if it finds any. The typical
location of the pstore on modern systems is the UEFI variable store.

Most distributions ship with CONFIG_EFI_VARS_PSTORE=m. That means, the
UEFI variable store is only available on boot after the respective module
is loaded.

In most situations, the pstore service gets loaded before the UEFI pstore,
so we don't get to transfer logs. Instead, they accumulate, filling up the
pstore over time, potentially breaking the UEFI variable store.

Let's add a service dependency on any kernel module that can provide a
pstore to ensure we only scan for pstate after we can actually see pstate.

I have seen live occurences of systems breaking because we did not erase
the pstates and ran out of UEFI nvram space.

Fixes https://github.com/systemd/systemd/issues/18540

(cherry picked from commit 70e74a5997ae2ce7ba72a74ac949c3b2dad1a1d6)

Related: #2158832
---
 units/systemd-pstore.service.in | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/units/systemd-pstore.service.in b/units/systemd-pstore.service.in
index 8cbf264a99..1983a9738f 100644
--- a/units/systemd-pstore.service.in
+++ b/units/systemd-pstore.service.in
@@ -16,6 +16,8 @@ DefaultDependencies=no
 After=systemd-remount-fs.service
 Conflicts=shutdown.target
 Before=sysinit.target shutdown.target
+After=modprobe@efi_pstore.service modprobe@mtdpstore.service modprobe@chromeos_pstore.service modprobe@ramoops.service modprobe@pstore_zone.service modprobe@pstore_blk.service
+Wants=modprobe@efi_pstore.service modprobe@mtdpstore.service modprobe@chromeos_pstore.service modprobe@ramoops.service modprobe@pstore_zone.service modprobe@pstore_blk.service
 
 [Service]
 Type=oneshot