diff options
| author | Zhang Qiao <zhangqiao22@huawei.com> | 2022-01-21 18:12:10 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-03-02 11:38:09 +0100 |
| commit | 4eec5fe1c680a6c47a9bc0cde00960a4eb663342 (patch) | |
| tree | 94e1f0298f77b899a18749db204e37c00cfb7a02 /kernel | |
| parent | 1763074989b3fdb49c4b6e38ad7d70c69f93076e (diff) | |
cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug
commit 05c7b7a92cc87ff8d7fde189d0fade250697573c upstream.
As previously discussed(https://lkml.org/lkml/2022/1/20/51),
cpuset_attach() is affected with similar cpu hotplug race,
as follow scenario:
cpuset_attach() cpu hotplug
--------------------------- ----------------------
down_write(cpuset_rwsem)
guarantee_online_cpus() // (load cpus_attach)
sched_cpu_deactivate
set_cpu_active()
// will change cpu_active_mask
set_cpus_allowed_ptr(cpus_attach)
__set_cpus_allowed_ptr_locked()
// (if the intersection of cpus_attach and
cpu_active_mask is empty, will return -EINVAL)
up_write(cpuset_rwsem)
To avoid races such as described above, protect cpuset_attach() call
with cpu_hotplug_lock.
Fixes: be367d099270 ("cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time")
Cc: stable@vger.kernel.org # v2.6.32+
Reported-by: Zhao Gongyi <zhaogongyi@huawei.com>
Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup/cpuset.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index ff956ccbb6df..d43d25acc95a 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1528,6 +1528,7 @@ static void cpuset_attach(struct cgroup_taskset *tset) cgroup_taskset_first(tset, &css); cs = css_cs(css); + cpus_read_lock(); mutex_lock(&cpuset_mutex); /* prepare for attach */ @@ -1583,6 +1584,7 @@ static void cpuset_attach(struct cgroup_taskset *tset) wake_up(&cpuset_attach_wq); mutex_unlock(&cpuset_mutex); + cpus_read_unlock(); } /* The various types of files and directories in a cpuset file system */ |