From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DD6D4392C48; Wed, 7 Oct 2026 21:04:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791407051; cv=none; b=P39tuicfpu6SUi4Z0zXTziAvskEV6PDC4QKo0dBvArEIk9wAcaCP8TnitQq6ORphubjvVfqeZ4IGmioeKZn9AgOJt6cxEz9PhriAJzS+tX5E7+xisTPsrwAc9sMfRDC9b6s0gO4Uoiz+OIpvcnXtXqzaZzeLX2fI0mwpLS7N1/8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791407051; c=relaxed/simple; bh=NJZZDmd5/DjRwi67pNPvxn0iG7rqWhAtG757Fftippg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=dbrMamfI0wEhUDyTP4WUgVVFmqyPWWIz0VTvtHiVDr0CLrldgyGFL23S8qLQwB9aOOorjVzEJ+jKZauuKWGrr2+hw6DKr7MCA1LPQxrVqZhfrDtOcmX0ATpG8RvUl2Z7DLRgY+oC7foZCUmu1FbQ+DeWsaGnceZ+9jyO1De1pqY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MtuJP9tu; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MtuJP9tu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 949261F00898; Wed, 7 Oct 2026 21:04:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791407049; bh=7Qa41V5u9j9ZQLrRsUE9jtEW0kajDdVSHkggXzVTAdU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MtuJP9tuzKP7CyQPqEh9NNxoDEkB6eWRefOON/xSLve+MLBap73eqn5i7Ft5YA0aG t95ptX/V+RP36RF28AAbz2kFqB5j7/UPFn5vH9kktBauxVUGDNX74HzHjtLHtC3SMG ZPDvC8AyGcaekLv+TePYgVSzTHXzXlhTuD2Z1ZJV4oG6uT9R/mEUrvDOvW47hK80gC Ou6D03tFmxaks5OmaB9ElF3plZDMQ5TgYk8uJTmyZcQxlhKBp/jk4xdMhwGCt/GvAl ZGH8vxqjxMoXJ8rP1HaApI8uxqMe9ehZbyUCNVeJdES/Wv2FmA6Jbw5TyjQSVLYhDb cGBvestJdk1dQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 5296ACE1716; Wed, 7 Oct 2026 14:04:09 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, Zqiang , "Paul E . McKenney" Subject: [PATCH v2 2/8] rcutorture: Synchronously wait for all rcu_torture_irq() callbacks to complete Date: Wed, 7 Oct 2026 14:04:02 -0700 Message-Id: <20261007210408.1983713-2-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Zqiang The rcu_torture_reader() drives RCU readers from interrupt context via smp_call_function_single(cpu, rcu_torture_irq, NULL, 0) with wait=0, to runs rcu_torture_irq() on a remote CPU. this is async, nothing waits for the remote handler to run. On shutdown, torture_stop_kthread() only waits for each reader kthread to return, and the reader's timer_delete_sync() only drains its timer. Neither waits for a rcu_torture_irq() which still pending or executing on a remote CPU, so it can run after all readers have exited and rcu_torture_cleanup() has already advanced. 1. rcu_torture_irq() may issue cur_ops->call(rhp, rcu_torture_timer_cb) after cur_ops->cb_barrier() has been waiting for all outstanding callbacks complete. once the module is unloaded, fires into freed module text, a use-after-free happen. 2. rcu_torture_irq() may still be inside rcu_torture_one_read(), holding a read-side critical section, when cur_ops->cleanup() tears the flavor down (e.g. cleanup_srcu_struct()), triggering an active-reader warning or use-after-free of the torn-down structure. This commit therefore issue a kick_all_cpus_sync() after all readers kthread have returned and before cur_ops->cb_barrier(), synchronous IPI round trip to every CPU guarantees that every rcu_torture_irq() which previously issued by any reader has completed. Signed-off-by: Zqiang Signed-off-by: Paul E. McKenney --- kernel/rcu/rcutorture.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 79807475b6724..51ed35f5aab17 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -4491,6 +4491,8 @@ rcu_torture_cleanup(void) for (i = 0; i < nrealreaders; i++) torture_stop_kthread(rcu_torture_reader, reader_tasks[i]); + if (irqreader && cur_ops->irq_capable) + kick_all_cpus_sync(); kfree(reader_tasks); reader_tasks = NULL; } -- 2.40.1