From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D15CCECAAD8 for ; Sun, 18 Sep 2022 15:54:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229733AbiIRPyE (ORCPT ); Sun, 18 Sep 2022 11:54:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229932AbiIRPxa (ORCPT ); Sun, 18 Sep 2022 11:53:30 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC3C71EC4D; Sun, 18 Sep 2022 08:53:29 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 58D526006F; Sun, 18 Sep 2022 15:53:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5DF75C4347C; Sun, 18 Sep 2022 15:53:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1663516408; bh=djdpWanOi4zWPI5MvBREvmwhOSv3FwS45ovTz/HZSl4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KfCosz0tEYKD25aaVLOYyBJvJG3AIHXJ0umANml2aOl8rUbGHeMhSPdLG2pki7eDq dNlGJo3NOYRF+IxXbm9AXmIgyyq+Rbnq+o714vDzCAbPen8yyfTaGt+Hudwd6iEF3a AAfGXlBsDCGFDuxDSNcH1rbTR5/+srnfZWS0c991EHQo80nPXq0gZTo/3ULUhlu0LU JixujdzO1sN3PXWnM3WPpDluQ/FVDasCswD3BL5meCMxvhZOwaqGDhj4Y5pRvBCbhg pGEBfF57UmqPi/TKV0drZF2L/nO7U8yjwAN8qDJ36yDR+fmAyHGKPEVeTq5h8wEIJ5 B4gtT8vYRk/vw== From: guoren@kernel.org To: arnd@arndb.de, guoren@kernel.org, palmer@rivosinc.com, tglx@linutronix.de, peterz@infradead.org, luto@kernel.org, conor.dooley@microchip.com, heiko@sntech.de, jszhang@kernel.org, lazyparser@gmail.com, falcon@tinylab.org, chenhuacai@kernel.org, apatel@ventanamicro.com, atishp@atishpatra.org, palmer@dabbelt.com, paul.walmsley@sifive.com, mark.rutland@arm.com, zouyipeng@huawei.com, bigeasy@linutronix.de, David.Laight@aculab.com Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Guo Ren Subject: [PATCH V5 06/11] entry: Prevent DEBUG_PREEMPT warning Date: Sun, 18 Sep 2022 11:52:41 -0400 Message-Id: <20220918155246.1203293-7-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220918155246.1203293-1-guoren@kernel.org> References: <20220918155246.1203293-1-guoren@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Guo Ren When DEBUG_PREEMPT=y, exit_to_user_mode_prepare ->tick_nohz_user_enter_prepare ->tick_nohz_full_cpu(smp_processor_id()) ->smp_processor_id() ->debug_smp_processor_id() ->check preempt_count() then: [ 5.717610] BUG: using smp_processor_id() in preemptible [00000000] code: S20urandom/94 [ 5.718111] caller is debug_smp_processor_id+0x24/0x38 [ 5.718417] CPU: 1 PID: 94 Comm: S20urandom Not tainted 6.0.0-rc3-00010-gfd0a0d619c63-dirty #238 [ 5.718886] Hardware name: riscv-virtio,qemu (DT) [ 5.719136] Call Trace: [ 5.719281] [] dump_backtrace+0x2c/0x3c [ 5.719566] [] show_stack+0x44/0x5c [ 5.720023] [] dump_stack_lvl+0x74/0xa4 [ 5.720557] [] dump_stack+0x1c/0x2c [ 5.721033] [] check_preemption_disabled+0x104/0x108 [ 5.721538] [] debug_smp_processor_id+0x24/0x38 [ 5.722001] [] exit_to_user_mode_prepare+0x48/0x178 [ 5.722355] [] irqentry_exit_to_user_mode+0x18/0x30 [ 5.722685] [] irqentry_exit+0x64/0xa4 [ 5.722953] [] do_page_fault+0x1d8/0x544 [ 5.723291] [] ret_from_exception+0x0/0xb8 (Above is found in riscv platform with generic_entry) The smp_processor_id() needs irqs disable or preempt_disable, so use preempt dis/in protecting the tick_nohz_user_enter_prepare(). Signed-off-by: Guo Ren Signed-off-by: Guo Ren --- kernel/entry/common.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/entry/common.c b/kernel/entry/common.c index 063068a9ea9b..36e4cd50531c 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -194,8 +194,10 @@ static void exit_to_user_mode_prepare(struct pt_regs *regs) lockdep_assert_irqs_disabled(); + preempt_disable(); /* Flush pending rcuog wakeup before the last need_resched() check */ tick_nohz_user_enter_prepare(); + preempt_enable(); if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK)) ti_work = exit_to_user_mode_loop(regs, ti_work); -- 2.36.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 835E5ECAAD8 for ; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org From: Guo Ren When DEBUG_PREEMPT=y, exit_to_user_mode_prepare ->tick_nohz_user_enter_prepare ->tick_nohz_full_cpu(smp_processor_id()) ->smp_processor_id() ->debug_smp_processor_id() ->check preempt_count() then: [ 5.717610] BUG: using smp_processor_id() in preemptible [00000000] code: S20urandom/94 [ 5.718111] caller is debug_smp_processor_id+0x24/0x38 [ 5.718417] CPU: 1 PID: 94 Comm: S20urandom Not tainted 6.0.0-rc3-00010-gfd0a0d619c63-dirty #238 [ 5.718886] Hardware name: riscv-virtio,qemu (DT) [ 5.719136] Call Trace: [ 5.719281] [] dump_backtrace+0x2c/0x3c [ 5.719566] [] show_stack+0x44/0x5c [ 5.720023] [] dump_stack_lvl+0x74/0xa4 [ 5.720557] [] dump_stack+0x1c/0x2c [ 5.721033] [] check_preemption_disabled+0x104/0x108 [ 5.721538] [] debug_smp_processor_id+0x24/0x38 [ 5.722001] [] exit_to_user_mode_prepare+0x48/0x178 [ 5.722355] [] irqentry_exit_to_user_mode+0x18/0x30 [ 5.722685] [] irqentry_exit+0x64/0xa4 [ 5.722953] [] do_page_fault+0x1d8/0x544 [ 5.723291] [] ret_from_exception+0x0/0xb8 (Above is found in riscv platform with generic_entry) The smp_processor_id() needs irqs disable or preempt_disable, so use preempt dis/in protecting the tick_nohz_user_enter_prepare(). Signed-off-by: Guo Ren Signed-off-by: Guo Ren --- kernel/entry/common.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/entry/common.c b/kernel/entry/common.c index 063068a9ea9b..36e4cd50531c 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -194,8 +194,10 @@ static void exit_to_user_mode_prepare(struct pt_regs *regs) lockdep_assert_irqs_disabled(); + preempt_disable(); /* Flush pending rcuog wakeup before the last need_resched() check */ tick_nohz_user_enter_prepare(); + preempt_enable(); if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK)) ti_work = exit_to_user_mode_loop(regs, ti_work); -- 2.36.1 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv