File 5009-cgroup-Restrict-effective-limits-with-global-resourc.patch of Package systemd.34838

From edfd70ab2c5490131fcf5a4348e31c19251d3479 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20Koutn=C3=BD?= <mkoutny@suse.com>
Date: Tue, 23 Jan 2024 11:30:20 +0100
Subject: [PATCH 5009/5011] cgroup: Restrict effective limits with global
 resource provision

Global resource (whole system or root cg's (e.g. in a container)) is
also a well-defined limit for memory and tasks, take it into account
when calculating effective limits.

(cherry picked from commit 93f8e88d23bd383b5134f32c1e2ee315ac3a38c8)

[mkoutny: fixes jsc#PED-5659]
---
 man/systemd.resource-control.xml |  2 +-
 src/core/cgroup.c                | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/man/systemd.resource-control.xml b/man/systemd.resource-control.xml
index 5b7900af87..ded4722e7a 100644
--- a/man/systemd.resource-control.xml
+++ b/man/systemd.resource-control.xml
@@ -422,7 +422,7 @@ CPUWeight=20   DisableControllers=cpu              /          \
           <literal>memory.max</literal> control group attribute. For details about this control group attribute, see
           <ulink url="https://docs.kernel.org/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.
           The effective configuration is reported as <varname>EffectiveMemoryMax=</varname> (the value is
-          the most stringent limit of the unit and parent slices).</para>
+          the most stringent limit of the unit and parent slices and it is capped by physical memory).</para>
 
           <para>While <varname>StartupMemoryMax=</varname> applies to the startup and shutdown phases of the system,
           <varname>MemoryMax=</varname> applies to normal runtime of the system, and if the former is not set also to
diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index 0842036559..a53d90486c 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -4006,6 +4006,17 @@ static uint64_t unit_get_effective_limit_one(Unit *u, CGroupLimitType type) {
         assert(u);
         assert(UNIT_HAS_CGROUP_CONTEXT(u));
 
+        if (unit_has_name(u, SPECIAL_ROOT_SLICE))
+                switch (type) {
+                        case CGROUP_LIMIT_MEMORY_MAX:
+                        case CGROUP_LIMIT_MEMORY_HIGH:
+                                return physical_memory();
+                        case CGROUP_LIMIT_TASKS_MAX:
+                                return system_tasks_max();
+                        default:
+                                assert_not_reached();
+                }
+
         cc = unit_get_cgroup_context(u);
         switch (type) {
                 /* Note: on legacy/hybrid hierarchies memory_max stays CGROUP_LIMIT_MAX unless configured
-- 
2.35.3