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authorZhang Qiao <zhangqiao22@huawei.com>2022-01-21 18:12:10 +0800
committerTejun Heo <tj@kernel.org>2022-02-14 09:48:04 -1000
commit05c7b7a92cc87ff8d7fde189d0fade250697573c (patch)
treeca03eee0d94326ebdd3915f3e0127bbbdc3d4289 /kernel/cgroup/cpuset.c
parent2bdfd2825c9662463371e6691b1a794e97fa36b4 (diff)
cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug
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>
Diffstat (limited to 'kernel/cgroup/cpuset.c')
-rw-r--r--kernel/cgroup/cpuset.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 4c7254e8f49a..97c53f3cc917 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2289,6 +2289,7 @@ static void cpuset_attach(struct cgroup_taskset *tset)
cgroup_taskset_first(tset, &css);
cs = css_cs(css);
+ cpus_read_lock();
percpu_down_write(&cpuset_rwsem);
guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
@@ -2342,6 +2343,7 @@ static void cpuset_attach(struct cgroup_taskset *tset)
wake_up(&cpuset_attach_wq);
percpu_up_write(&cpuset_rwsem);
+ cpus_read_unlock();
}
/* The various types of files and directories in a cpuset file system */