[PATCH] rcu: fix hotplug-cpu ->donelist leak

Pointed out by Srivatsa Vaddagiri <[e-mail]>.

rcu_do_batch() stops after processing maxbatch callbacks
on ->donelist leaving rcu_tasklet in TASKLET_STATE_SCHED
state.

If CPU_DEAD event happens remaining ->donelist entries are
lost, rcu_offline_cpu() kills this tasklet.

With this patch ->donelist migrates along with ->curlist
and ->nxtlist to the current cpu.

Compile tested.

Signed-off-by: Oleg Nesterov <[e-mail]>
Acked-by: Paul E. McKenney <[e-mail]>
Cc: Srivatsa Vaddagiri <[e-mail]>
Cc: Dipankar Sarma <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/rcupdate.c

···
 	spin_unlock_bh(&rcp->lock);
 	rcu_move_batch(this_rdp, rdp->curlist, rdp->curtail);
 	rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail);
-
+	rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail);
 }
+
 static void rcu_offline_cpu(int cpu)
 {
 	struct rcu_data *this_rdp = &get_cpu_var(rcu_data);