Re: [PATCH] cgroup: fixed the cset refcnt leak when fork() failed

[Waiman Long]

On 6/5/23 10:12, Waiman Long wrote:
> > kernel/cgroup/cgroup.c | 5 +++++
> >   1 file changed, 5 insertions(+)
> >
> > diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
> > index d18c2ef..5ecd706 100644
> > --- a/kernel/cgroup/cgroup.c
> > +++ b/kernel/cgroup/cgroup.c
> > @@ -6284,6 +6284,11 @@ void cgroup_cancel_fork(struct task_struct 
> > *child,
> >           if (ss->cancel_fork)
> >               ss->cancel_fork(child, kargs->cset);
> >   +    if (!(kargs->flags & CLONE_INTO_CGROUP) &&
> > +            kargs->cset) {
> > +        put_css_set(kargs->cset);
> > +    }
> > +
> I believe the out_revert error path of cgroup_can_fork() has a similar 
> issue. Perhaps you may want to put the put_css_set() call in 
> cgroup_css_set_put_fork().

Sorry, it should not be done in cgroup_css_set_put_fork(). As the 
increase in reference is properly matched in css_post_fork(). That means 
similar change will be needed in cgroup_can_fork().

Cheers,
Longman