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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2022-08-25 17:38:38 +0900
committerTejun Heo <tj@kernel.org>2022-08-25 07:36:30 -1000
commit43626dade36fa74d3329046f4ae2d7fdefe401c6 (patch)
tree06f2784c54257714e1576003999fae747af04df7 /kernel/cgroup
parent763f4fb76e24959c370cdaa889b2492ba6175580 (diff)
cgroup: Add missing cpus_read_lock() to cgroup_attach_task_all()
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>
Diffstat (limited to 'kernel/cgroup')
-rw-r--r--kernel/cgroup/cgroup-v1.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 2ade21b54dc4..ff6a8099eb2a 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -59,6 +59,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
int retval = 0;
mutex_lock(&cgroup_mutex);
+ cpus_read_lock();
percpu_down_write(&cgroup_threadgroup_rwsem);
for_each_root(root) {
struct cgroup *from_cgrp;
@@ -72,6 +73,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
break;
}
percpu_up_write(&cgroup_threadgroup_rwsem);
+ cpus_read_unlock();
mutex_unlock(&cgroup_mutex);
return retval;