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Date: Sun, 11 Nov 2018 11:32:15 -0800
From: "Paul E. McKenney" <paulmck@...ux.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
"Paul E. McKenney" <paulmck@...ux.ibm.com>
Subject: [PATCH tip/core/rcu 2/4] rcu: Eliminate BUG_ON() for kernel/rcu/tree.c
The tree.c file has a number of calls to BUG_ON(), which panics the
kernel, which is not a good strategy for devices (like embedded) that
don't have a way to capture console output. This commit therefore
converts these BUG_ON() calls to WARN_ON_ONCE() and WARN_ONCE().
Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@...ux.ibm.com>
---
kernel/rcu/tree.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 121f833acd04..bdb6659a8dbc 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2826,7 +2826,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func, int cpu, bool lazy)
* Very early boot, before rcu_init(). Initialize if needed
* and then drop through to queue the callback.
*/
- BUG_ON(cpu != -1);
+ WARN_ON_ONCE(cpu != -1);
WARN_ON_ONCE(!rcu_is_watching());
if (rcu_segcblist_empty(&rdp->cblist))
rcu_segcblist_init(&rdp->cblist);
@@ -3485,7 +3485,8 @@ static int __init rcu_spawn_gp_kthread(void)
rcu_scheduler_fully_active = 1;
t = kthread_create(rcu_gp_kthread, NULL, "%s", rcu_state.name);
- BUG_ON(IS_ERR(t));
+ if (WARN_ONCE(IS_ERR(t), "%s: Could not start grace-period kthread, OOM is now expected behavior\n", __func__))
+ return 0;
rnp = rcu_get_root();
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rcu_state.gp_kthread = t;
--
2.17.1
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