From: Qi Zheng zhengqi.arch@bytedance.com

mainline inclusion from mainline-v6.4-rc6 commit ab1de7ead871ebe6d12a774c3c25de0388cde082 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7RPDX CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id...

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The commit 4f7e7236435c ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock") fixed the deadlock between cgroup_threadgroup_rwsem and cpus_read_lock() by introducing cgroup_attach_{lock,unlock}() and removing cpus_read_{lock,unlock}() from cpuset_attach(). But cgroup_transfer_tasks() was missed and not handled, which will cause th following warning:

WARNING: CPU: 0 PID: 589 at kernel/cpu.c:526 lockdep_assert_cpus_held+0x32/0x40 CPU: 0 PID: 589 Comm: kworker/1:4 Not tainted 6.4.0-rc2-next-20230517 #50 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 Workqueue: events cpuset_hotplug_workfn RIP: 0010:lockdep_assert_cpus_held+0x32/0x40 <...> Call Trace: <TASK> cpuset_attach+0x40/0x240 cgroup_migrate_execute+0x452/0x5e0 ? _raw_spin_unlock_irq+0x28/0x40 cgroup_transfer_tasks+0x1f3/0x360 ? find_held_lock+0x32/0x90 ? cpuset_hotplug_workfn+0xc81/0xed0 cpuset_hotplug_workfn+0xcb1/0xed0 ? process_one_work+0x248/0x5b0 process_one_work+0x2b9/0x5b0 worker_thread+0x56/0x3b0 ? process_one_work+0x5b0/0x5b0 kthread+0xf1/0x120 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 </TASK>

So just use the cgroup_attach_{lock,unlock}() helper to fix it.

Reported-by: Zhao Gongyi zhaogongyi@bytedance.com Signed-off-by: Qi Zheng zhengqi.arch@bytedance.com Acked-by: Muchun Song songmuchun@bytedance.com Fixes: 05c7b7a92cc8 ("cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug") Cc: stable@vger.kernel.org # v5.17+ Signed-off-by: Tejun Heo tj@kernel.org conflicts: kernel/cgroup/cgroup-v1.c Signed-off-by: Cai Xinchen caixinchen1@huawei.com --- kernel/cgroup/cgroup-v1.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index 8bd36f2143eb..2e3748b1a333 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -105,7 +105,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)

mutex_lock(&cgroup_mutex);

- percpu_down_write(&cgroup_threadgroup_rwsem); + cgroup_attach_lock();

/* all tasks in @from are being moved, all csets are source */ spin_lock_irq(&css_set_lock); @@ -141,7 +141,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) } while (task && !ret); out_err: cgroup_migrate_finish(&mgctx); - percpu_up_write(&cgroup_threadgroup_rwsem); + cgroup_attach_unlock(); mutex_unlock(&cgroup_mutex); return ret; }