Gentle ping on this patch. 在 2022/1/21 18:12, Zhang Qiao 写道: > 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") > Reported-by: Zhao Gongyi <zhaogongyi@xxxxxxxxxx> > Signed-off-by: Zhang Qiao <zhangqiao22@xxxxxxxxxx> > --- > kernel/cgroup/cpuset.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index dc653ab26e50..0af5725cc1df 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -2252,6 +2252,7 @@ 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); > @@ -2305,6 +2306,7 @@ 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 */ > -- > 2.18.0 > > . >
