linux-kernel - [PATCH/for-next 0/2] cgroup/cpuset: Fix partition related locking issues

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Message-ID: <20260128044251.1229702-1-longman@redhat.com>
Date: Tue, 27 Jan 2026 23:42:49 -0500
From: Waiman Long <longman@...hat.com>
To: Chen Ridong <chenridong@...weicloud.com>,
	Tejun Heo <tj@...nel.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Koutný <mkoutny@...e.com>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Frederic Weisbecker <frederic@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Shuah Khan <shuah@...nel.org>
Cc: cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	Waiman Long <longman@...hat.com>
Subject: [PATCH/for-next 0/2] cgroup/cpuset: Fix partition related locking issues

After booting the latest cgroup for-next debug kernel with the latest
cgroup changes as well as Federic's "cpuset/isolation: Honour kthreads
preferred affinity" patch series [1] merged on top and running the
test-cpuset-prs.sh test, a circular locking dependency lockdep splat
was reported. See patch 2 for details.

The following changes are made to resolve this locking problem.
 1) Deferring calling housekeeping_update() from CPU hotplug to task work
 2) Release cpus_read_lock before calling housekeeping_update()

With these changes, the cpuset test ran to completion with no failure
and no lockdep splat.

[1] https://lore.kernel.org/lkml/20260125224541.50226-1-frederic@kernel.org/

Waiman Long (2):
  cgroup/cpuset: Defer housekeeping_update() call from CPU hotplug to
    task_work
  cgroup/cpuset: Introduce a new top level isolcpus_update_mutex

 kernel/cgroup/cpuset.c                        | 124 ++++++++++++++----
 kernel/sched/isolation.c                      |   4 +-
 kernel/time/timer_migration.c                 |   3 +-
 .../selftests/cgroup/test_cpuset_prs.sh       |   9 ++
 4 files changed, 111 insertions(+), 29 deletions(-)

-- 
2.52.0