From 7d44d0d43465892d4753ff50592588f49d56cf95 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Thu, 10 Sep 2015 12:32:16 +0200

Subject: [PATCH] core: add support for the "pids" cgroup controller

This adds support for the new "pids" cgroup controller of 4.3 kernels.

It allows accounting the number of tasks in a cgroup and enforcing

limits on it.

This adds two new setting TasksAccounting= and TasksMax= to each unit,

as well as a gloabl option DefaultTasksAccounting=.

This also updated "cgtop" to optionally make use of the new

kernel-provided accounting.

systemctl has been updated to show the number of tasks for each service

if it is available.

This patch also adds correct support for undoing memory limits for units

using a MemoryLimit=infinity syntax. We do the same for TasksMax= now

and hence keep things in sync here.

Cherry-picked from: 03a7b521e3ffb7f5d153d90480ba5d4bc29d1e8f

Resolves: #1337244

---

 man/systemd-system.conf.xml           | 22 +++++-----

 man/systemd.resource-control.xml      | 63 ++++++++++++++++++++++-----

 src/core/cgroup.c                     | 44 +++++++++++++++++++

 src/core/cgroup.h                     |  5 +++

 src/core/dbus-cgroup.c                | 41 ++++++++++++++++-

 src/core/dbus-unit.c                  | 25 +++++++++++

 src/core/load-fragment-gperf.gperf.m4 |  2 +

 src/core/load-fragment.c              | 37 ++++++++++++++--

 src/core/load-fragment.h              |  1 +

 src/core/main.c                       |  3 ++

 src/core/manager.h                    |  1 +

 src/core/unit.c                       |  1 +

 src/shared/cgroup-util.h              |  1 +

 src/systemctl/systemctl.c             | 17 ++++++++

 14 files changed, 236 insertions(+), 27 deletions(-)

diff --git a/man/systemd-system.conf.xml b/man/systemd-system.conf.xml

index 57b3b90be1..d367ccd130 100644

--- a/man/systemd-system.conf.xml

+++ b/man/systemd-system.conf.xml

@@ -51,14 +51,14 @@

   </refnamediv>

   <refsynopsisdiv>

-    <para><filename>/etc/systemd/system.conf</filename></para>

-    <para><filename>/etc/systemd/system.conf.d/*.conf</filename></para>

-    <para><filename>/run/systemd/system.conf.d/*.conf</filename></para>

-    <para><filename>/usr/lib/systemd/system.conf.d/*.conf</filename></para>

-    <para><filename>/etc/systemd/user.conf</filename></para>

-    <para><filename>/etc/systemd/user.conf.d/*.conf</filename></para>

-    <para><filename>/run/systemd/user.conf.d/*.conf</filename></para>

-    <para><filename>/usr/lib/systemd/user.conf.d/*.conf</filename></para>

+    <para><filename>/etc/systemd/system.conf</filename>,

+    <filename>/etc/systemd/system.conf.d/*.conf</filename>,

+    <filename>/run/systemd/system.conf.d/*.conf</filename>,

+    <filename>/usr/lib/systemd/system.conf.d/*.conf</filename></para>

+    <para><filename>/etc/systemd/user.conf</filename>,

+    <filename>/etc/systemd/user.conf.d/*.conf</filename>,

+    <filename>/run/systemd/user.conf.d/*.conf</filename>,

+    <filename>/usr/lib/systemd/user.conf.d/*.conf</filename></para>

   </refsynopsisdiv>

   <refsect1>

@@ -307,12 +307,14 @@

         <term><varname>DefaultCPUAccounting=</varname></term>

         <term><varname>DefaultBlockIOAccounting=</varname></term>

         <term><varname>DefaultMemoryAccounting=</varname></term>

+        <term><varname>DefaultTasksAccounting=</varname></term>

         <listitem><para>Configure the default resource accounting

         settings, as configured per-unit by

         <varname>CPUAccounting=</varname>,

-        <varname>BlockIOAccounting=</varname> and

-        <varname>MemoryAccounting=</varname>. See

+        <varname>BlockIOAccounting=</varname>,

+        <varname>MemoryAccounting=</varname> and

+        <varname>TasksAccounting=</varname>. See

         <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>

         for details on the per-unit settings.</para></listitem>

       </varlistentry>

diff --git a/man/systemd.resource-control.xml b/man/systemd.resource-control.xml

index 8f4e7a3f16..6b9329bbee 100644

--- a/man/systemd.resource-control.xml

+++ b/man/systemd.resource-control.xml

@@ -103,10 +103,10 @@

         <listitem>

           <para>Turn on CPU usage accounting for this unit. Takes a

           boolean argument. Note that turning on CPU accounting for

-          one unit might also implicitly turn it on for all units

+          one unit will also implicitly turn it on for all units

           contained in the same slice and for all its parent slices

           and the units contained therein. The system default for this

-          setting maybe controlled with

+          setting may be controlled with

           <varname>DefaultCPUAccounting=</varname> in

           <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>

         </listitem>

@@ -134,7 +134,7 @@

           prioritizing specific services at boot-up differently than

           during normal runtime.</para>

-          <para>Those options imply

+          <para>These options imply

           <literal>CPUAccounting=true</literal>.</para>

         </listitem>

       </varlistentry>

@@ -168,9 +168,10 @@

         <listitem>

           <para>Turn on process and kernel memory accounting for this

           unit. Takes a boolean argument. Note that turning on memory

-          accounting for one unit might also implicitly turn it on for

-          all its parent slices. The system default for this setting

-          maybe controlled with

+          accounting for one unit will also implicitly turn it on for

+          all units contained in the same slice and for all its parent

+          slices and the units contained therein. The system default

+          for this setting may be controlled with

           <varname>DefaultMemoryAccounting=</varname> in

           <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>

         </listitem>

@@ -186,26 +187,64 @@

           memory size in bytes. If the value is suffixed with K, M, G

           or T, the specified memory size is parsed as Kilobytes,

           Megabytes, Gigabytes, or Terabytes (with the base 1024),

-          respectively. This controls the

-          <literal>memory.limit_in_bytes</literal> control group

-          attribute. For details about this control group attribute,

-          see 

+          respectively. If assigned the special value

+          <literal>infinity</literal> no memory limit is applied. This

+          controls the <literal>memory.limit_in_bytes</literal>

+          control group attribute. For details about this control

+          group attribute, see 

           url="https://www.kernel.org/doc/Documentation/cgroups/memory.txt">memory.txt</ulink>.</para>

           <para>Implies <literal>MemoryAccounting=true</literal>.</para>

         </listitem>

       </varlistentry>

+      <varlistentry>

+        <term><varname>TasksAccounting=</varname></term>

+

+        <listitem>

+          <para>Turn on task accounting for this unit. Takes a

+          boolean argument. If enabled, the system manager will keep

+          track of the number of tasks in the unit. The number of

+          tasks accounted this way includes both kernel threads and

+          userspace processes, with each thread counting

+          individually. Note that turning on tasks accounting for one

+          unit will also implicitly turn it on for all units contained

+          in the same slice and for all its parent slices and the

+          units contained therein. The system default for this setting

+          may be controlled with

+          <varname>DefaultTasksAccounting=</varname> in

+          <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>

+        </listitem>

+      </varlistentry>

+

+      <varlistentry>

+        <term><varname>TasksMax=<replaceable>N</replaceable></varname></term>

+

+        <listitem>

+          <para>Specify the maximum number of tasks that may be

+          created in the unit. This ensures that the number of tasks

+          accounted for the unit (see above) stays below a specific

+          limit. If assigned the special value

+          <literal>infinity</literal> no tasks limit is applied. This

+          controls the <literal>pids.max</literal> control group

+          attribute. For details about this control group attribute,

+          see 

+          url="https://www.kernel.org/doc/Documentation/cgroups/pids.txt">pids.txt</ulink>.</para>

+

+          <para>Implies <literal>TasksAccounting=true</literal>.</para>

+        </listitem>

+      </varlistentry>

+

       <varlistentry>

         <term><varname>BlockIOAccounting=</varname></term>

         <listitem>

           <para>Turn on Block IO accounting for this unit. Takes a

           boolean argument. Note that turning on block IO accounting

-          for one unit might also implicitly turn it on for all units

+          for one unit will also implicitly turn it on for all units

           contained in the same slice and all for its parent slices

           and the units contained therein. The system default for this

-          setting maybe controlled with

+          setting may be controlled with

           <varname>DefaultBlockIOAccounting=</varname> in

           <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>

         </listitem>

diff --git a/src/core/cgroup.c b/src/core/cgroup.c

index b7f08fb420..d4a8f9cbe3 100644

--- a/src/core/cgroup.c

+++ b/src/core/cgroup.c

@@ -40,6 +40,7 @@ void cgroup_context_init(CGroupContext *c) {

         c->memory_limit = (uint64_t) -1;

         c->blockio_weight = (unsigned long) -1;

         c->startup_blockio_weight = (unsigned long) -1;

+        c->tasks_max = (uint64_t) -1;

         c->cpu_quota_per_sec_usec = USEC_INFINITY;

 }

@@ -105,6 +106,7 @@ void cgroup_context_dump(CGroupContext *c, FILE* f, const char *prefix) {

                 "%sBlockIOWeight=%lu\n"

                 "%sStartupBlockIOWeight=%lu\n"

                 "%sMemoryLimit=%" PRIu64 "\n"

+                "%sTasksMax=%" PRIu64 "\n"

                 "%sDevicePolicy=%s\n"

                 "%sDelegate=%s\n",

                 prefix, yes_no(c->cpu_accounting),

@@ -116,6 +118,7 @@ void cgroup_context_dump(CGroupContext *c, FILE* f, const char *prefix) {

                 prefix, c->blockio_weight,

                 prefix, c->startup_blockio_weight,

                 prefix, c->memory_limit,

+                prefix, c->tasks_max,

                 prefix, cgroup_device_policy_to_string(c->device_policy),

                 prefix, yes_no(c->delegate));

@@ -456,6 +459,21 @@ void cgroup_context_apply(CGroupContext *c, CGroupControllerMask mask, const cha

                                 log_debug("Ignoring device %s while writing cgroup attribute.", a->path);

                 }

         }

+

+        if ((mask & CGROUP_PIDS) && !is_root) {

+

+                if (c->tasks_max != (uint64_t) -1) {

+                        char buf[DECIMAL_STR_MAX(uint64_t) + 2];

+

+                        sprintf(buf, "%" PRIu64 "\n", c->tasks_max);

+                        r = cg_set_attribute("pids", path, "pids.max", buf);

+                } else

+                        r = cg_set_attribute("pids", path, "pids.max", "max");

+

+                if (r < 0)

+                        log_full_errno(IN_SET(r, -ENOENT, -EROFS) ? LOG_DEBUG : LOG_WARNING, r,

+                                       "Failed to set pids.max on %s: %m", path);

+        }

 }

 CGroupControllerMask cgroup_context_get_mask(CGroupContext *c) {

@@ -484,6 +502,10 @@ CGroupControllerMask cgroup_context_get_mask(CGroupContext *c) {

             c->device_policy != CGROUP_AUTO)

                 mask |= CGROUP_DEVICE;

+        if (c->tasks_accounting ||

+            c->tasks_max != (uint64_t) -1)

+                mask |= CGROUP_PIDS;

+

         return mask;

 }

@@ -1044,6 +1066,28 @@ int manager_notify_cgroup_empty(Manager *m, const char *cgroup) {

         return 0;

 }

+int unit_get_tasks_current(Unit *u, uint64_t *ret) {

+        _cleanup_free_ char *v = NULL;

+        int r;

+

+        assert(u);

+       assert(ret);

+

+        if (!u->cgroup_path)

+                return -ENODATA;

+

+        if ((u->cgroup_realized_mask & CGROUP_PIDS) == 0)

+                return -ENODATA;

+

+        r = cg_get_attribute("pids", u->cgroup_path, "pids.current", &v);

+        if (r == -ENOENT)

+                return -ENODATA;

+        if (r < 0)

+                return r;

+

+        return safe_atou64(v, ret);

+}

+

 static const char* const cgroup_device_policy_table[_CGROUP_DEVICE_POLICY_MAX] = {

         [CGROUP_AUTO] = "auto",

         [CGROUP_CLOSED] = "closed",

diff --git a/src/core/cgroup.h b/src/core/cgroup.h

index 8fa851de32..8af3eaa3ae 100644

--- a/src/core/cgroup.h

+++ b/src/core/cgroup.h

@@ -72,6 +72,7 @@ struct CGroupContext {

         bool cpu_accounting;

         bool blockio_accounting;

         bool memory_accounting;

+        bool tasks_accounting;

         unsigned long cpu_shares;

         unsigned long startup_cpu_shares;

@@ -88,6 +89,8 @@ struct CGroupContext {

         LIST_HEAD(CGroupDeviceAllow, device_allow);

         bool delegate;

+

+        uint64_t tasks_max;

 };

 #include "unit.h"

@@ -127,5 +130,7 @@ pid_t unit_search_main_pid(Unit *u);

 int manager_notify_cgroup_empty(Manager *m, const char *group);

+int unit_get_tasks_current(Unit *u, uint64_t *ret);

+

 const char* cgroup_device_policy_to_string(CGroupDevicePolicy i) _const_;

 CGroupDevicePolicy cgroup_device_policy_from_string(const char *s) _pure_;

diff --git a/src/core/dbus-cgroup.c b/src/core/dbus-cgroup.c

index 4a9df06016..a4465dc7aa 100644

--- a/src/core/dbus-cgroup.c

+++ b/src/core/dbus-cgroup.c

@@ -168,6 +168,8 @@ const sd_bus_vtable bus_cgroup_vtable[] = {

         SD_BUS_PROPERTY("MemoryLimit", "t", NULL, offsetof(CGroupContext, memory_limit), 0),

         SD_BUS_PROPERTY("DevicePolicy", "s", property_get_cgroup_device_policy, offsetof(CGroupContext, device_policy), 0),

         SD_BUS_PROPERTY("DeviceAllow", "a(ss)", property_get_device_allow, 0, 0),

+        SD_BUS_PROPERTY("TasksAccounting", "b", bus_property_get_bool, offsetof(CGroupContext, tasks_accounting), 0),

+        SD_BUS_PROPERTY("TasksMax", "t", NULL, offsetof(CGroupContext, tasks_max), 0),

         SD_BUS_VTABLE_END

 };

@@ -551,7 +553,11 @@ int bus_cgroup_set_property(

                 if (mode != UNIT_CHECK) {

                         c->memory_limit = limit;

                         u->cgroup_realized_mask &= ~CGROUP_MEMORY;

-                        unit_write_drop_in_private_format(u, mode, name, "%s=%" PRIu64, name, limit);

+

+                        if (limit == (uint64_t) -1)

+                                unit_write_drop_in_private(u, mode, name, "MemoryLimit=infinity");

+                        else

+                                unit_write_drop_in_private_format(u, mode, name, "MemoryLimit=%" PRIu64, limit);

                 }

                 return 1;

@@ -667,6 +673,39 @@ int bus_cgroup_set_property(

                 return 1;

+        } else if (streq(name, "TasksAccounting")) {

+                int b;

+

+                r = sd_bus_message_read(message, "b", &b);

+                if (r < 0)

+                        return r;

+

+                if (mode != UNIT_CHECK) {

+                        c->tasks_accounting = b;

+                        u->cgroup_realized_mask &= ~CGROUP_PIDS;

+                        unit_write_drop_in_private(u, mode, name, b ? "TasksAccounting=yes" : "TasksAccounting=no");

+                }

+

+                return 1;

+

+        } else if (streq(name, "TasksMax")) {

+                uint64_t limit;

+

+                r = sd_bus_message_read(message, "t", &limit);

+                if (r < 0)

+                        return r;

+

+                if (mode != UNIT_CHECK) {

+                        c->tasks_max = limit;

+                        u->cgroup_realized_mask &= ~CGROUP_PIDS;

+

+                        if (limit == (uint64_t) -1)

+                                unit_write_drop_in_private(u, mode, name, "TasksMax=infinity");

+                        else

+                                unit_write_drop_in_private_format(u, mode, name, "TasksMax=%" PRIu64, limit);

+                }

+

+                return 1;

         }

         if (u->transient && u->load_state == UNIT_STUB) {

diff --git a/src/core/dbus-unit.c b/src/core/dbus-unit.c

index 056a17ac1f..1d0d6f67c7 100644

--- a/src/core/dbus-unit.c

+++ b/src/core/dbus-unit.c

@@ -673,11 +673,36 @@ static int property_get_current_memory(

         return sd_bus_message_append(reply, "t", sz);

 }

+static int property_get_current_tasks(

+                sd_bus *bus,

+                const char *path,

+                const char *interface,

+                const char *property,

+                sd_bus_message *reply,

+                void *userdata,

+                sd_bus_error *error) {

+

+        uint64_t cn = (uint64_t) -1;

+        Unit *u = userdata;

+        int r;

+

+        assert(bus);

+        assert(reply);

+        assert(u);

+

+        r = unit_get_tasks_current(u, &cn;;

+        if (r < 0 && r != -ENODATA)

+                log_unit_warning_errno(u->id, r, "Failed to get pids.current attribute: %m");

+

+        return sd_bus_message_append(reply, "t", cn);

+}

+

 const sd_bus_vtable bus_unit_cgroup_vtable[] = {

         SD_BUS_VTABLE_START(0),

         SD_BUS_PROPERTY("Slice", "s", property_get_slice, 0, 0),

         SD_BUS_PROPERTY("ControlGroup", "s", NULL, offsetof(Unit, cgroup_path), 0),

         SD_BUS_PROPERTY("MemoryCurrent", "t", property_get_current_memory, 0, 0),

+        SD_BUS_PROPERTY("TasksCurrent", "t", property_get_current_tasks, 0, 0),

         SD_BUS_VTABLE_END

 };

diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4

index f996032cf2..26e4c618ee 100644

--- a/src/core/load-fragment-gperf.gperf.m4

+++ b/src/core/load-fragment-gperf.gperf.m4

@@ -125,6 +125,8 @@ $1.StartupBlockIOWeight,         config_parse_blockio_weight,        0,

 $1.BlockIODeviceWeight,          config_parse_blockio_device_weight, 0,                             offsetof($1, cgroup_context)

 $1.BlockIOReadBandwidth,         config_parse_blockio_bandwidth,     0,                             offsetof($1, cgroup_context)

 $1.BlockIOWriteBandwidth,        config_parse_blockio_bandwidth,     0,                             offsetof($1, cgroup_context)

+$1.TasksAccounting,              config_parse_bool,                  0,                             offsetof($1, cgroup_context.tasks_accounting)

+$1.TasksMax,                     config_parse_tasks_max,             0,                             offsetof($1, cgroup_context)

 $1.Delegate,                     config_parse_bool,                  0,                             offsetof($1, cgroup_context.delegate)'

 )m4_dnl

 Unit.Description,                config_parse_unit_string_printf,    0,                             offsetof(Unit, description)

diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c

index 7d1ac6c251..7d2e737d05 100644

--- a/src/core/load-fragment.c

+++ b/src/core/load-fragment.c

@@ -3052,7 +3052,7 @@ int config_parse_memory_limit(

         off_t bytes;

         int r;

-        if (isempty(rvalue)) {

+        if (isempty(rvalue) || streq(rvalue, "infinity")) {

                 c->memory_limit = (uint64_t) -1;

                 return 0;

         }

@@ -3060,9 +3060,8 @@ int config_parse_memory_limit(

         assert_cc(sizeof(uint64_t) == sizeof(off_t));

         r = parse_size(rvalue, 1024, &bytes);

-        if (r < 0) {

-                log_syntax(unit, LOG_ERR, filename, line, EINVAL,

-                           "Memory limit '%s' invalid. Ignoring.", rvalue);

+        if (r < 0 || bytes < 1) {

+                log_syntax(unit, LOG_ERR, filename, line, EINVAL, "Memory limit '%s' invalid. Ignoring.", rvalue);

                 return 0;

         }

@@ -3070,6 +3069,36 @@ int config_parse_memory_limit(

         return 0;

 }

+int config_parse_tasks_max(

+                const char *unit,

+                const char *filename,

+                unsigned line,

+                const char *section,

+                unsigned section_line,

+                const char *lvalue,

+                int ltype,

+                const char *rvalue,

+                void *data,

+                void *userdata) {

+

+        CGroupContext *c = data;

+        uint64_t u;

+        int r;

+

+        if (isempty(rvalue) || streq(rvalue, "infinity")) {

+                c->tasks_max = (uint64_t) -1;

+                return 0;

+        }

+

+        r = safe_atou64(rvalue, &u);

+        if (r < 0 || u < 1) {

+                log_syntax(unit, LOG_ERR, filename, line, EINVAL, "Maximum tasks value '%s' invalid. Ignoring.", rvalue);

+                return 0;

+        }

+

+        return 0;

+}

+

 int config_parse_device_allow(

                 const char *unit,

                 const char *filename,

diff --git a/src/core/load-fragment.h b/src/core/load-fragment.h

index 2059353d38..8d334f2c86 100644

--- a/src/core/load-fragment.h

+++ b/src/core/load-fragment.h

@@ -89,6 +89,7 @@ int config_parse_pass_environ(const char *unit, const char *filename, unsigned l

 int config_parse_unit_slice(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

 int config_parse_cpu_shares(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

 int config_parse_memory_limit(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

+int config_parse_tasks_max(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

 int config_parse_device_policy(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

 int config_parse_device_allow(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

 int config_parse_blockio_weight(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

diff --git a/src/core/main.c b/src/core/main.c

index cba992cea2..aca05a5358 100644

--- a/src/core/main.c

+++ b/src/core/main.c

@@ -117,6 +117,7 @@ static bool arg_default_cpu_accounting = false;

 static bool arg_default_blockio_accounting = false;

 static bool arg_default_memory_accounting = false;

 static EmergencyAction arg_cad_burst_action = EMERGENCY_ACTION_REBOOT_FORCE;

+static bool arg_default_tasks_accounting = false;

 static void nop_handler(int sig) {}

@@ -676,6 +677,7 @@ static int parse_config_file(void) {

                 { "Manager", "DefaultBlockIOAccounting",  config_parse_bool,             0, &arg_default_blockio_accounting        },

                 { "Manager", "DefaultMemoryAccounting",   config_parse_bool,             0, &arg_default_memory_accounting         },

                 { "Manager", "CtrlAltDelBurstAction",     config_parse_emergency_action, 0, &arg_cad_burst_action                  },

+                { "Manager", "DefaultTasksAccounting",    config_parse_bool,             0, &arg_default_tasks_accounting          },

                 {}

         };

@@ -1685,6 +1687,7 @@ int main(int argc, char *argv[]) {

         m->default_cpu_accounting = arg_default_cpu_accounting;

         m->default_blockio_accounting = arg_default_blockio_accounting;

         m->default_memory_accounting = arg_default_memory_accounting;

+        m->default_tasks_accounting = arg_default_tasks_accounting;

         m->runtime_watchdog = arg_runtime_watchdog;

         m->shutdown_watchdog = arg_shutdown_watchdog;

diff --git a/src/core/manager.h b/src/core/manager.h

index 231c076b10..96dcd83dc0 100644

--- a/src/core/manager.h

+++ b/src/core/manager.h

@@ -261,6 +261,7 @@ struct Manager {

         bool default_cpu_accounting;

         bool default_memory_accounting;

         bool default_blockio_accounting;

+        bool default_tasks_accounting;

         usec_t default_timer_accuracy_usec;

diff --git a/src/core/unit.c b/src/core/unit.c

index 103f92084c..2fcb4fbf07 100644

--- a/src/core/unit.c

+++ b/src/core/unit.c

@@ -126,6 +126,7 @@ static void unit_init(Unit *u) {

                 cc->cpu_accounting = u->manager->default_cpu_accounting;

                 cc->blockio_accounting = u->manager->default_blockio_accounting;

                 cc->memory_accounting = u->manager->default_memory_accounting;

+                cc->tasks_accounting = u->manager->default_tasks_accounting;

         }

         ec = unit_get_exec_context(u);

diff --git a/src/shared/cgroup-util.h b/src/shared/cgroup-util.h

index 96a3d3bafa..31bd8d311f 100644

--- a/src/shared/cgroup-util.h

+++ b/src/shared/cgroup-util.h

@@ -35,6 +35,7 @@ typedef enum CGroupControllerMask {

         CGROUP_BLKIO = 4,

         CGROUP_MEMORY = 8,

         CGROUP_DEVICE = 16,

+        CGROUP_PIDS = 32,

         _CGROUP_CONTROLLER_MASK_ALL = 31

 } CGroupControllerMask;

diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c

index 0333599c87..b1862b5676 100644

--- a/src/systemctl/systemctl.c

+++ b/src/systemctl/systemctl.c

@@ -3280,6 +3280,8 @@ typedef struct UnitStatusInfo {

         /* CGroup */

         uint64_t memory_current;

         uint64_t memory_limit;

+        uint64_t tasks_current;

+        uint64_t tasks_max;

         LIST_HEAD(ExecStatusInfo, exec);

 } UnitStatusInfo;

@@ -3539,6 +3541,15 @@ static void print_status_info(

         if (i->status_errno > 0)

                 printf("    Error: %i (%s)\n", i->status_errno, strerror(i->status_errno));

+        if (i->tasks_current != (uint64_t) -1) {

+                printf("    Tasks: %" PRIu64, i->tasks_current);

+

+                if (i->tasks_max != (uint64_t) -1)

+                        printf(" (limit: %" PRIi64 ")\n", i->tasks_max);

+                else

+                        printf("\n");

+        }

+

         if (i->memory_current != (uint64_t) -1) {

                 char buf[FORMAT_BYTES_MAX];

@@ -3768,6 +3779,10 @@ static int status_property(const char *name, sd_bus_message *m, UnitStatusInfo *

                         i->memory_current = u;

                 else if (streq(name, "MemoryLimit"))

                         i->memory_limit = u;

+                else if (streq(name, "TasksCurrent"))

+                        i->tasks_current = u;

+                else if (streq(name, "TasksMax"))

+                        i->tasks_max = u;

                 break;

         }

@@ -4248,6 +4263,8 @@ static int show_one(

         UnitStatusInfo info = {

                 .memory_current = (uint64_t) -1,

                 .memory_limit = (uint64_t) -1,

+                .tasks_current = (uint64_t) -1,

+                .tasks_max = (uint64_t) -1,

         };

         ExecStatusInfo *p;

         int r;