From: Kunwu Chan <kunwu.chan@gmail.com>
To: jiangshanlai@gmail.com, paulmck@kernel.org,
josh@joshtriplett.org, work@onurozkan.dev, frederic@kernel.org,
neeraj.upadhyay@kernel.org, joelagnelf@nvidia.com,
boqun@kernel.org, urezki@gmail.com
Cc: rostedt@goodmis.org, mathieu.desnoyers@efficios.com,
qiang.zhang@linux.dev, rcu@vger.kernel.org,
linux-kernel@vger.kernel.org, Kunwu Chan <kunwu.chan@gmail.com>,
Kunwu Chan <chentao@kylinos.cn>
Subject: [PATCH v2 09/10] rcu-tasks: Detect duplicate callback enqueue
Date: Tue, 27 Oct 2026 15:09:22 +0800 [thread overview]
Message-ID: <20261027070923.3054462-10-kunwu.chan@gmail.com> (raw)
In-Reply-To: <20261027070923.3054462-1-kunwu.chan@gmail.com>
Detect duplicate callback enqueue attempts in the generic
RCU Tasks callback registration path. Use __ratelimit()
for the diagnostic output group.
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
---
kernel/rcu/tasks.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 5d7f234795b4..d5d060a5c4b6 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -6,6 +6,8 @@
*/
#ifdef CONFIG_TASKS_RCU_GENERIC
+#include <linux/mm.h>
+#include <linux/ratelimit.h>
#include "rcu_segcblist.h"
////////////////////////////////////////////////////////////////////////
@@ -339,6 +341,12 @@ static void call_rcu_tasks_iw_wakeup(struct irq_work *iwp)
}
// Enqueue a callback for the specified flavor of Tasks RCU.
+static void rcu_tasks_leak_callback(struct rcu_head *rhp) { }
+
+static DEFINE_RATELIMIT_STATE(rcu_tasks_dup_rs,
+ DEFAULT_RATELIMIT_INTERVAL,
+ DEFAULT_RATELIMIT_BURST);
+
static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func,
struct rcu_tasks *rtp)
{
@@ -358,6 +366,17 @@ static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func,
if (WARN_ON_ONCE(!func))
return;
+ if (debug_rcu_head_queue(rhp)) {
+ if (__ratelimit(&rcu_tasks_dup_rs)) {
+ pr_err("%s(): Duplicate CB for %s, %p->%pS()\n",
+ __func__, rtp->name, rhp, rhp->func);
+ mem_dump_obj(rhp);
+ dump_stack();
+ }
+ WRITE_ONCE(rhp->func, rcu_tasks_leak_callback);
+ return;
+ }
+
rhp->next = NULL;
rhp->func = func;
local_irq_save(flags);
@@ -586,6 +605,7 @@ static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp, struct rcu_tasks_percpu
raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);
len = rcl.len;
for (rhp = rcu_cblist_dequeue(&rcl); rhp; rhp = rcu_cblist_dequeue(&rcl)) {
+ debug_rcu_head_unqueue(rhp);
debug_rcu_head_callback(rhp);
local_bh_disable();
rhp->func(rhp);
--
2.43.0
next prev parent reply other threads:[~2026-10-27 7:11 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-27 7:09 [PATCH v2 00/10] rcu: Improve callback diagnostics and validation Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 01/10] srcu: Record callback registration stack for KASAN Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 02/10] srcutiny: " Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 03/10] rcu: Record callback registration stack for Tiny RCU Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 04/10] srcu: Validate callback arguments Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 05/10] rcu: Validate callback arguments in Tiny RCU Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 06/10] rcu-tasks: Validate callback arguments Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 07/10] srcu: Detect duplicate callback enqueue at registration Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 08/10] srcutiny: Detect duplicate callback enqueue Kunwu Chan
2026-10-27 7:09 ` Kunwu Chan [this message]
2026-10-27 7:09 ` [PATCH v2 10/10] rcu: Improve duplicate callback diagnostics Kunwu Chan
2026-10-27 23:13 ` [PATCH v2 00/10] rcu: Improve callback diagnostics and validation Joel Fernandes
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