From: Zqiang <qiang.zhang1211@gmail.com>
[ Upstream commit 1bba3900ca18bdae28d1b9fa10f16a8f8cb2ada1 ]
In the preparation stage of CPU online, if the corresponding
the rdp's->nocb_cb_kthread does not exist, will be created,
there is a situation where the rdp's rcuop kthreads creation fails,
and then de-offload this CPU's rdp, does not assign this CPU's
rdp->nocb_cb_kthread pointer, but this rdp's->nocb_gp_rdp and
rdp's->rdp_gp->nocb_gp_kthread is still valid.
This will cause the subsequent re-offload operation of this offline
CPU, which will pass the conditional check and the kthread_unpark()
will access invalid rdp's->nocb_cb_kthread pointer.
This commit therefore use rdp's->nocb_gp_kthread instead of
rdp_gp's->nocb_gp_kthread for safety check.
Signed-off-by: Zqiang <qiang.zhang1211@gmail.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
[ Minor conflict resolved. ]
Signed-off-by: Jianqiang kang <jianqkang@sina.cn>
---
kernel/rcu/tree_nocb.h | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
index 7c28d154b094..2f501de7bec9 100644
--- a/kernel/rcu/tree_nocb.h
+++ b/kernel/rcu/tree_nocb.h
@@ -1112,7 +1112,6 @@ static long rcu_nocb_rdp_offload(void *arg)
struct rcu_segcblist *cblist = &rdp->cblist;
unsigned long flags;
int wake_gp;
- struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
WARN_ON_ONCE(rdp->cpu != raw_smp_processor_id());
/*
@@ -1122,7 +1121,7 @@ static long rcu_nocb_rdp_offload(void *arg)
if (!rdp->nocb_gp_rdp)
return -EINVAL;
- if (WARN_ON_ONCE(!rdp_gp->nocb_gp_kthread))
+ if (WARN_ON_ONCE(!rdp->nocb_gp_kthread))
return -EINVAL;
pr_info("Offloading %d\n", rdp->cpu);
@@ -1151,7 +1150,7 @@ static long rcu_nocb_rdp_offload(void *arg)
*/
wake_gp = rdp_offload_toggle(rdp, true, flags);
if (wake_gp)
- wake_up_process(rdp_gp->nocb_gp_kthread);
+ wake_up_process(rdp->nocb_gp_kthread);
swait_event_exclusive(rdp->nocb_state_wq,
rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB) &&
rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_GP));
--
2.34.1