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cgroups/systemd: allow to set -1 as pids.limit 

Currently, both systemd cgroup drivers (v1 and v2) only set
"TasksMax" unit property if the value > 0, so there is no
way to update the limit to -1 / unlimited / infinity / max.

Since systemd driver is backed by fs driver, and both fs and fs2
set the limit of -1 properly, it works, but systemd still has
the old value:

 # runc --systemd-cgroup update $CT --pids-limit 42
 # systemctl show runc-$CT.scope | grep TasksMax
 TasksMax=42
 # cat /sys/fs/cgroup/system.slice/runc-$CT.scope/pids.max
 42

 # ./runc --systemd-cgroup update $CT --pids-limit -1
 # systemctl show runc-$CT.scope | grep TasksMax=
 TasksMax=42
 # cat /sys/fs/cgroup/system.slice/runc-xx77.scope/pids.max
 max

Fix by changing the condition to allow -1 as a valid value.

NOTE other negative values are still being ignored by systemd drivers
(as it was done before). I am not sure whether this is correct, or
should we return an error.

A test case is added.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Kir Kolyshkin 2020-05-04 19:19:46 -07:00
parent 95413ecdb0
commit 59897367c4
3 changed files with 8 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
libcontainer/cgroups/systemd/v1.go
View File

@ -125,7 +125,7 @@ func genV1ResourcesProperties(c *configs.Cgroup) ([]systemdDbus.Property, error)
newProp("BlockIOWeight", uint64(c.Resources.BlkioWeight))) newProp("BlockIOWeight", uint64(c.Resources.BlkioWeight)))
} }
if c.Resources.PidsLimit > 0 { if c.Resources.PidsLimit > 0 || c.Resources.PidsLimit == -1 {
properties = append(properties, properties = append(properties,
newProp("TasksAccounting", true), newProp("TasksAccounting", true),
newProp("TasksMax", uint64(c.Resources.PidsLimit))) newProp("TasksMax", uint64(c.Resources.PidsLimit)))

2
libcontainer/cgroups/systemd/v2.go
View File

@ -92,7 +92,7 @@ func genV2ResourcesProperties(c *configs.Cgroup) ([]systemdDbus.Property, error)
newProp("CPUQuotaPerSecUSec", cpuQuotaPerSecUSec)) newProp("CPUQuotaPerSecUSec", cpuQuotaPerSecUSec))
} }
if c.Resources.PidsLimit > 0 { if c.Resources.PidsLimit > 0 || c.Resources.PidsLimit == -1 {
properties = append(properties, properties = append(properties,
newProp("TasksAccounting", true), newProp("TasksAccounting", true),
newProp("TasksMax", uint64(c.Resources.PidsLimit))) newProp("TasksMax", uint64(c.Resources.PidsLimit)))

6
tests/integration/update.bats
View File

@ -161,6 +161,12 @@ EOF
check_cgroup_value "pids.max" 10 check_cgroup_value "pids.max" 10
check_systemd_value "TasksMax" 10 check_systemd_value "TasksMax" 10
# unlimited
runc update test_update --pids-limit -1
[ "$status" -eq 0 ]
check_cgroup_value "pids.max" max
check_systemd_value "TasksMax" $SD_UNLIMITED
# Revert to the test initial value via json on stdin # Revert to the test initial value via json on stdin
runc update -r - test_update <<EOF runc update -r - test_update <<EOF
{ {