diff options
| author | Zhang Qiao <zhangqiao22@huawei.com> | 2022-03-17 10:41:57 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-03-23 09:10:41 +0100 |
| commit | aa44002e7db25f333ddf412fb81e8db6c100841a (patch) | |
| tree | 4970f25f31e353e1789524735c39061c74e35cbf /kernel | |
| parent | 1ba1ec19460247ebe8b41c9a883d55f633c1282d (diff) | |
cpuset: Fix unsafe lock order between cpuset lock and cpuslock
The backport commit 4eec5fe1c680a ("cgroup/cpuset: Fix a race
between cpuset_attach() and cpu hotplug") looks suspicious since
it comes before commit d74b27d63a8b ("cgroup/cpuset: Change
cpuset_rwsem and hotplug lock order") v5.4-rc1~176^2~30 when
the locking order was: cpuset lock, cpus lock.
Fix it with the correct locking order and reduce the cpus locking
range because only set_cpus_allowed_ptr() needs the protection of
cpus lock.
Fixes: 4eec5fe1c680a ("cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug")
Reported-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup/cpuset.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index d43d25acc95a..153628277a48 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1528,9 +1528,13 @@ static void cpuset_attach(struct cgroup_taskset *tset) cgroup_taskset_first(tset, &css); cs = css_cs(css); - cpus_read_lock(); mutex_lock(&cpuset_mutex); + /* + * It should hold cpus lock because a cpu offline event can + * cause set_cpus_allowed_ptr() failed. + */ + get_online_cpus(); /* prepare for attach */ if (cs == &top_cpuset) cpumask_copy(cpus_attach, cpu_possible_mask); @@ -1549,6 +1553,7 @@ static void cpuset_attach(struct cgroup_taskset *tset) cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to); cpuset_update_task_spread_flag(cs, task); } + put_online_cpus(); /* * Change mm for all threadgroup leaders. This is expensive and may @@ -1584,7 +1589,6 @@ 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 */ |