[PATCH 1/1] UBUNTU: SAUCE: Enable upstream config option "CONFIG_CPUSETS_V1"

[Mehmet Basaran]

BugLink: https://bugs.launchpad.net/bugs/2128722

For noble, some of the applied upstream commits are using "CONFIG_CPUSETS_V1"
to enable/disable some code paths. This changes the behaviour of cpusets and
currently noble is neither V1 nor V2. Because of this, "cpuset_inherit" and
"cpuset_hotplug" test cases are failing in ubuntu_ltp_controllers test suite.

cpuset_inherit 37 TFAIL: memory_migrate: Test result - 1 Expected string - "0"
cpuset_inherit 39 TFAIL: memory_migrate: Test result - 1 Expected string - "0"
cpuset_inherit 49 TFAIL: sched_load_balance: Test result - 0 Expected string - "1"

cpuset_hotplug 1 TINFO: CPUs are numbered continuously starting at 0 (0-1)
cpuset_hotplug 1 TINFO: Nodes are numbered continuously starting at 0 (0)
cpuset_hotplug 1 TFAIL: root group's cpus isn't expected(Result: 0-1, Expect: 0).
cpuset_hotplug 5 TFAIL: general group's cpus isn't expected(Result: 0-1, Expect: 0).
cpuset_hotplug 7 TFAIL: test task was still in general group, but its cpus is NULL
cpuset_hotplug 11 TFAIL: task's cpu present list isn't expected(Result: 0-1, Expect: 0).

For noble, we have to use v1 because there is no support for v2. Added
"CONFIG_CPUSETS_V1" kernel config option. This was added to upstream via
the following commit:

    [ Upstream commit 1abab1ba0775036bb67c6c57945c637be644c04f ]
    cgroup/cpuset: guard cpuset-v1 code under CONFIG_CPUSETS_V1

I have chosen to go with a SAUCE patch since, the commit above depends on
other commits. And in the future, we can revert this one and apply the
dependent commits if we want to follow cpusets follow from 6.12 versions so
that there are less conflicts between upstream stable and noble sources.

The other solution is to remove the use of "CONFIG_CPUSETS_V1" macro from
sources. However this will also cause noble and upstream stable sources to
diverge and make it difficult to backport patches.

Signed-off-by: Mehmet Basaran <mehmet.basaran at canonical.com>
---
 debian.master/config/annotations |  1 +
 init/Kconfig                     | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/debian.master/config/annotations b/debian.master/config/annotations
index 9ebb2a92ba55..3f3150b3aa99 100644
--- a/debian.master/config/annotations
+++ b/debian.master/config/annotations
@@ -3293,6 +3293,7 @@ CONFIG_CPU5_WDT                                 policy<{'amd64': 'm'}>
 CONFIG_CPUFREQ_DT_PLATDEV                       policy<{'arm64': 'y', 'armhf': 'y', 'ppc64el': 'y', 'riscv64': 'y'}>
 CONFIG_CPUMASK_OFFSTACK                         policy<{'amd64': 'y'}>
 CONFIG_CPUSETS                                  policy<{'amd64': 'y', 'arm64': 'y', 'armhf': 'y', 'ppc64el': 'y', 'riscv64': 'y', 's390x': 'y'}>
+CONFIG_CPUSETS_V1                               policy<{'amd64': 'y', 'arm64': 'y', 'armhf': 'y', 'ppc64el': 'y', 'riscv64': 'y', 's390x': 'y'}>
 CONFIG_CPU_32v6K                                policy<{'armhf': 'y'}>
 CONFIG_CPU_32v7                                 policy<{'armhf': 'y'}>
 CONFIG_CPU_ABRT_EV7                             policy<{'armhf': 'y'}>
diff --git a/init/Kconfig b/init/Kconfig
index 426c2464f653..3b728ed594cc 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1143,6 +1143,19 @@ config CPUSETS
 
 	  Say N if unsure.
 
+config CPUSETS_V1
+       bool "Legacy cgroup v1 cpusets controller"
+       depends on CPUSETS
+       default n
+       help
+         Legacy cgroup v1 cpusets controller which has been deprecated by
+         cgroup v2 implementation. The v1 is there for legacy applications
+         which haven't migrated to the new cgroup v2 interface yet. If you
+         do not have any such application then you are completely fine leaving
+         this option disabled.
+
+         Say N if unsure.
+
 config PROC_PID_CPUSET
 	bool "Include legacy /proc/<pid>/cpuset file"
 	depends on CPUSETS
-- 
2.43.0