| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.15 44/45] cgroup: Add missing cpus_read_lock() to cgroup_attach_task_all() | Date | Wed, 21 Sep 2022 17:46:34 +0200 |
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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
commit 43626dade36fa74d3329046f4ae2d7fdefe401c6 upstream.
syzbot is hitting percpu_rwsem_assert_held(&cpu_hotplug_lock) warning at cpuset_attach() [1], for commit 4f7e7236435ca0ab ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock") missed that cpuset_attach() is also called from cgroup_attach_task_all(). Add cpus_read_lock() like what cgroup_procs_write_start() does.
Link: https://syzkaller.appspot.com/bug?extid=29d3a3b4d86c8136ad9e [1] Reported-by: syzbot <syzbot+29d3a3b4d86c8136ad9e@syzkaller.appspotmail.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Fixes: 4f7e7236435ca0ab ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock") Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- kernel/cgroup/cgroup-v1.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -59,6 +59,7 @@ int cgroup_attach_task_all(struct task_s int retval = 0; mutex_lock(&cgroup_mutex); + cpus_read_lock(); percpu_down_write(&cgroup_threadgroup_rwsem); for_each_root(root) { struct cgroup *from_cgrp; @@ -75,6 +76,7 @@ int cgroup_attach_task_all(struct task_s break; } percpu_up_write(&cgroup_threadgroup_rwsem); + cpus_read_unlock(); mutex_unlock(&cgroup_mutex); return retval;
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