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Tejun Heo 3bf4bf5406 cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock

[ Upstream commit 4f7e723643 ]

Bringing up a CPU may involve creating and destroying tasks which requires
read-locking threadgroup_rwsem, so threadgroup_rwsem nests inside
cpus_read_lock(). However, cpuset's ->attach(), which may be called with
thredagroup_rwsem write-locked, also wants to disable CPU hotplug and
acquires cpus_read_lock(), leading to a deadlock.

Fix it by guaranteeing that ->attach() is always called with CPU hotplug
disabled and removing cpus_read_lock() call from cpuset_attach().

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-and-tested-by: Imran Khan <imran.f.khan@oracle.com>
Reported-and-tested-by: Xuewen Yan <xuewen.yan@unisoc.com>
Fixes: 05c7b7a92c ("cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug")
Cc: stable@vger.kernel.org # v5.17+
Signed-off-by: Sasha Levin <sashal@kernel.org>

2022-09-15 11:30:03 +02:00

cgroup-internal.h

cgroup: Use open-time cgroup namespace for process migration perm checks

2022-01-11 15:35:15 +01:00

cgroup-v1.c

cgroup-v1: Correct privileges check in release_agent writes

2022-03-02 11:47:47 +01:00

cgroup.c

cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock

2022-09-15 11:30:03 +02:00

cpuset.c

cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock