From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 70E4234AB12; Mon, 18 Aug 2025 14:01:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755525699; cv=none; b=iNMUxksvMCixGe3qK62LW++DjQz0N9NuIAjJHLQYAuvcfdSzmZpJfZ7+fVcGGbJZXRAz/RHmt8TnarIZ6kn/g+/DCP5LDlsjBRDmtMRrzYywtZJXR07hsXan0eltvQlSm4prIDXgKxMYLOKUs/3YStuCVwi+g4vMpxo3UfeW40w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755525699; c=relaxed/simple; bh=dDjsH4FMrPsfi1oK42WtABQO5wCfEzsP0AtuzmWgxsM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZywsG5VHPcdc8yCra8yhcbH1TV9ek36s9pgOP7c8qRRII+8HE9HYoI3lOGWA5PCiU8SBVGZLJwlXVXwKcQvQQllpXyfCBH8iq3O+FYkG3ljXQ1/smgTerqk89HrVNzAA9gj3jBFrHY/lw1SMrGgWXlc/vjBGLNBqiicaHNkM90w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EUdfbNst; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="EUdfbNst" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 44E41C4CEEB; Mon, 18 Aug 2025 14:01:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755525699; bh=dDjsH4FMrPsfi1oK42WtABQO5wCfEzsP0AtuzmWgxsM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EUdfbNstw9nhblMBFH9PmvpZzz8j4juJ4fH2RjH0SWmGvTZHaOkOntP4QXxKcEcxZ MLOB1eKuA4KN+9y1ckXYHOyse8VomQ3npfYzfZ7Mh8il4mG2YMzPgBReXt5ftFePLU vVQ4QSyqpVx+ItezDSyRCzrPxq5Uoovd3ZJRNOgE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Paul E. McKenney" , Zqiang , Joel Fernandes , "Neeraj Upadhyay (AMD)" , Sasha Levin Subject: [PATCH 6.16 308/570] rcutorture: Fix rcutorture_one_extend_check() splat in RT kernels Date: Mon, 18 Aug 2025 14:44:55 +0200 Message-ID: <20250818124517.738636363@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250818124505.781598737@linuxfoundation.org> References: <20250818124505.781598737@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zqiang [ Upstream commit 8d71351d88e478d3c4e945e3218e97ec677fd807 ] For built with CONFIG_PREEMPT_RT=y kernels, running rcutorture tests resulted in the following splat: [ 68.797425] rcutorture_one_extend_check during change: Current 0x1 To add 0x1 To remove 0x0 preempt_count() 0x0 [ 68.797533] WARNING: CPU: 2 PID: 512 at kernel/rcu/rcutorture.c:1993 rcutorture_one_extend_check+0x419/0x560 [rcutorture] [ 68.797601] Call Trace: [ 68.797602] [ 68.797619] ? lockdep_softirqs_off+0xa5/0x160 [ 68.797631] rcutorture_one_extend+0x18e/0xcc0 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797646] ? local_clock+0x19/0x40 [ 68.797659] rcu_torture_one_read+0xf0/0x280 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797678] ? __pfx_rcu_torture_one_read+0x10/0x10 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797804] ? __pfx_rcu_torture_timer+0x10/0x10 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797815] rcu-torture: rcu_torture_reader task started [ 68.797824] rcu-torture: Creating rcu_torture_reader task [ 68.797824] rcu_torture_reader+0x238/0x580 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797836] ? kvm_sched_clock_read+0x15/0x30 Disable BH does not change the SOFTIRQ corresponding bits in preempt_count() for RT kernels, this commit therefore use softirq_count() to check the if BH is disabled. Reviewed-by: Paul E. McKenney Signed-off-by: Zqiang Signed-off-by: Joel Fernandes Signed-off-by: Neeraj Upadhyay (AMD) Signed-off-by: Sasha Levin --- kernel/rcu/rcutorture.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 70ec0f21abc3..1d4635f8bb43 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -464,7 +464,7 @@ rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp) !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) { started = cur_ops->get_gp_seq(); ts = rcu_trace_clock_local(); - if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK)) + if ((preempt_count() & HARDIRQ_MASK) || softirq_count()) longdelay_ms = 5; /* Avoid triggering BH limits. */ mdelay(longdelay_ms); rtrsp->rt_delay_ms = longdelay_ms; @@ -1930,7 +1930,7 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old, return; WARN_ONCE((curstate & (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH)) && - !(preempt_count() & SOFTIRQ_MASK), ROEC_ARGS); + !softirq_count(), ROEC_ARGS); WARN_ONCE((curstate & (RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED)) && !(preempt_count() & PREEMPT_MASK), ROEC_ARGS); WARN_ONCE(cur_ops->readlock_nesting && @@ -1944,7 +1944,7 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old, WARN_ONCE(cur_ops->extendables && !(curstate & (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH)) && - (preempt_count() & SOFTIRQ_MASK), ROEC_ARGS); + softirq_count(), ROEC_ARGS); /* * non-preemptible RCU in a preemptible kernel uses preempt_disable() @@ -1965,6 +1965,9 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old, if (!IS_ENABLED(CONFIG_PREEMPT_RCU)) mask |= RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED; + if (IS_ENABLED(CONFIG_PREEMPT_RT) && softirq_count()) + mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH; + WARN_ONCE(cur_ops->readlock_nesting && !(curstate & mask) && cur_ops->readlock_nesting() > 0, ROEC_ARGS); } -- 2.39.5