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 23481CCA47B for ; Sun, 5 Jun 2022 13:57:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348371AbiFEN5a (ORCPT ); Sun, 5 Jun 2022 09:57:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347740AbiFEN4A (ORCPT ); Sun, 5 Jun 2022 09:56:00 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6FB63DFE2; Sun, 5 Jun 2022 06:55:28 -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 A763460FC5; Sun, 5 Jun 2022 13:55:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8366DC34115; Sun, 5 Jun 2022 13:55:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654437312; bh=h4il9NEwlDhRClIoY7hNjlMkV92f7fL2oN4YkoUeJsM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a6xIyBD7H0Wf+6LPx7UQ1nj7bxkgRGrHdWrS8szvY/pNsmMcPy8rWQVNTjf67wvHp HlJv+L+1//Mx9T1/3NhZZb4pBIRA7TQeT6wQ9ZuHeQs+LebEN18AegoGvWFSLo7hRI TxaiFXI/qushYsIdVGqzjiX5M/PnetatiFUEy6N6gPco3j3jCPQ37V4lbkHqwDYX+h S6qmBn1B2YtXbRnWFLeLAaIR36LB9w0V4o+GpMtpvOdyYE+PxXGxiT0/IhwDjHXifP SQePlIdQ+Myqp8rcB1RzSsQVewQB33PakBkyQ2Xp18Id0909WQR8qiTriK54eSjgRA z9dccOi3/0+lg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sebastian Andrzej Siewior , Thomas Gleixner , Sasha Levin Subject: [PATCH MANUALSEL 5.4 3/4] lib/irq_poll: Prevent softirq pending leak in irq_poll_cpu_dead() Date: Sun, 5 Jun 2022 09:54:59 -0400 Message-Id: <20220605135503.61690-3-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220605135503.61690-1-sashal@kernel.org> References: <20220605135503.61690-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sebastian Andrzej Siewior [ Upstream commit 75d8cce128c516fe6cf4b8683e8fe1a59e919902 ] irq_poll_cpu_dead() pulls the blk_cpu_iopoll backlog from the dead CPU and raises the POLL softirq with __raise_softirq_irqoff() on the CPU it is running on. That just sets the bit in the pending softirq mask. This means the handling of the softirq is delayed until the next interrupt or a local_bh_disable/enable() pair. As a consequence the CPU on which this code runs can reach idle with the POLL softirq pending, which triggers a warning in the NOHZ idle code. Add a local_bh_disable/enable() pair around the interrupts disabled section in irq_poll_cpu_dead(). local_bh_enable will handle the pending softirq. [tglx: Massaged changelog and comment] Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/87k0bxgl27.ffs@tglx Signed-off-by: Sasha Levin --- lib/irq_poll.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/lib/irq_poll.c b/lib/irq_poll.c index 2f17b488d58e..2d5329a42105 100644 --- a/lib/irq_poll.c +++ b/lib/irq_poll.c @@ -188,14 +188,18 @@ EXPORT_SYMBOL(irq_poll_init); static int irq_poll_cpu_dead(unsigned int cpu) { /* - * If a CPU goes away, splice its entries to the current CPU - * and trigger a run of the softirq + * If a CPU goes away, splice its entries to the current CPU and + * set the POLL softirq bit. The local_bh_disable()/enable() pair + * ensures that it is handled. Otherwise the current CPU could + * reach idle with the POLL softirq pending. */ + local_bh_disable(); local_irq_disable(); list_splice_init(&per_cpu(blk_cpu_iopoll, cpu), this_cpu_ptr(&blk_cpu_iopoll)); __raise_softirq_irqoff(IRQ_POLL_SOFTIRQ); local_irq_enable(); + local_bh_enable(); return 0; } -- 2.35.1