mm: hugetlb: switch to css_tryget() in hugetlb_cgroup_charge_cgroup()
An exiting task might belong to an offline cgroup. In this case an attempt to grab a cgroup reference from the task can end up with an infinite loop in hugetlb_cgroup_charge_cgroup(), because neither the cgroup will become online, neither the task will be migrated to a live cgroup. Fix this by switching over to css_tryget(). As css_tryget_online() can't guarantee that the cgroup won't go offline, in most cases the check doesn't make sense. In this particular case users of hugetlb_cgroup_charge_cgroup() are not affected by this change. A similar problem is described by commit 18fa84a2 ("cgroup: Use css_tryget() instead of css_tryget_online() in task_get_css()"). Link: http://lkml.kernel.org/r/20191106225131.3543616-2-guro@fb.com Signed-off-by:Roman Gushchin <guro@fb.com> Acked-by:
Johannes Weiner <hannes@cmpxchg.org> Acked-by:
Tejun Heo <tj@kernel.org> Reviewed-by:
Shakeel Butt <shakeelb@google.com> Cc: Michal Hocko <mhocko@ke...
parent
00d484f3
Please register or sign in to comment