Merge pull request #17363 from keszybz/oomd-meson-and-news

oomd meson and NEWS adjustments

NEWS

@@ -495,17 +495,6 @@ CHANGES WITH 247 in spe:
           such as replay debuggers where non-deterministic behaviour is not
           desirable.
 
-        * When building systemd the Meson option
-          -Dcompat-mutable-uid-boundaries may now be specified. If enabled,
-          systemd reads the system UID boundaries from /etc/login.defs, instead
-          of using the built-in values selected during build-time. This is an
-          option to improve compatibility for upgrades from old systems. It's
-          strongly recommended not to make use of this functionality on new
-          systems (or even enable it during build), as it makes something
-          runtime-configurable that is mostly an implementation detail of the
-          OS, and permits avoidable differences in deployments that create all
-          kinds of problems in the long run.
-
         * The autopaging logic in systemd's various tools (such as systemctl)
           has been updated to turn on "secure" mode in "less"
           (i.e. $LESSECURE=1) if execution in a "sudo" environment is
@@ -513,6 +502,44 @@ CHANGES WITH 247 in spe:
           via the pipe logic. This behaviour may be overridden via the new
           $SYSTEMD_PAGERSECURE environment variable.
 
+        * Units which have resource limits (.service, .mount, .swap, .slice,
+          .socket, and .slice) gained new configuration settings
+          ManagedOOMSwap=, ManagedOOMMemoryPressure=, and
+          ManagedOOMMemoryPressureLimitPercent= that speicify resource pressure
+          limits and optional action taken by systemd-oomd.
+
+        * A new service systemd-oomd has been added. It monitors resource
+          contention for selected parts of the unit hierarchy using the PSI
+          information reported by the kernel, and kills processes when memory
+          or swap pressure is above configured limits. This service is only
+          enabled in developer mode (see below) and should be considered a
+          preview in this release. Behaviour details and option names are
+          subject to change without the usual backwards-compatibility promises.
+
+        * A new helper oomctl has been added to introspect systemd-oomd state.
+          If also is only available in developer mode and should be considered
+          a preview without the usual backwards-compatibility promises.
+
+        * New meson option -Dcompat-mutable-uid-boundaries= has been added. If
+          enabled, systemd reads the system UID boundaries from /etc/login.defs
+          at runtime, instead of using the built-in values selected during
+          build. This is an option to improve compatibility for upgrades from
+          old systems. It's strongly recommended not to make use of this
+          functionality on new systems (or even enable it during build), as it
+          makes something runtime-configurable that is mostly an implementation
+          detail of the OS, and permits avoidable differences in deployments
+          that create all kinds of problems in the long run.
+
+        * New meson option '-Dmode=developer|release' has been added. When
+          'developer', additional checks and features are enabled that are
+          relevant during upstream development, e.g. verification that
+          semi-automatically-generated documentation has been properly updated
+          following API changes. Those checks are considered hints for
+          developers and are not actionable in downstream builds. In addition,
+          extra features that are not ready for general consumption may be
+          enabled in developer mode. It is thus recommended to set
+          '-Dmode=release' in end-user and distro builds.
+
 CHANGES WITH 246:
 
         * The service manager gained basic support for cgroup v2 freezer. Units

meson.build

@@ -1412,7 +1412,15 @@ conf.set10('ENABLE_HOMED', have)
 have = have and conf.get('HAVE_PAM') == 1
 conf.set10('ENABLE_PAM_HOME', have)
 
-have = get_option('oomd') and get_option('mode') == 'developer'
+have = get_option('oomd')
+if have == 'auto'
+        have = get_option('mode') == 'developer'
+else
+        have = have == 'true'
+        if have and get_option('mode') != 'developer'
+                error('oomd is not available in release mode (yet)')
+        endif
+endif
 conf.set10('ENABLE_OOMD', have)
 
 want_remote = get_option('remote')

meson_options.txt

@@ -97,7 +97,7 @@ option('coredump', type : 'boolean',
        description : 'install the coredump handler')
 option('pstore', type : 'boolean',
        description : 'install the pstore archival tool')
-option('oomd', type : 'boolean', value : 'false',
+option('oomd', type : 'combo', choices : ['auto', 'true', 'false'],
        description : 'install the userspace oom killer')
 option('logind', type : 'boolean',
        description : 'install the systemd-logind stack')