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 74B38C5479D for ; Mon, 9 Jan 2023 21:57:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237270AbjAIV5k (ORCPT ); Mon, 9 Jan 2023 16:57:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235477AbjAIV5S (ORCPT ); Mon, 9 Jan 2023 16:57:18 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 75EB9100F for ; Mon, 9 Jan 2023 13:57:16 -0800 (PST) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1673301433; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=crQggRCCTS9KBx/w5xi4+o+X/zIwoXHiy4Qxywl0rDY=; b=jlhroFq0hxX606/TPil8wehF7+JDsZOfxdrARjn596nzoPnZKntRgSd5B0I6u3D7LnEeWE GsagpDDtjim395PeSYkqvD58jgt5eBJYzDid2C0ySb7pMsrRFepGaMMJBAPQyHn8EVKseV yaJYjMvwfbwZrWewMiuj1sxZLTVKVyZZVXWNNck12KUaRQRozg76SeGCavZ6bwx3eLVe/1 iqhIPM5BPejrIZFeQ9tqe2/sSHs1wAGJdbCqiT4kRgiuXV06sC/kqNBimwwXHua2WrijbV fx0g6XHKV5zv5s+VP1Ci/+tpROThGXTxQuqDBw7EI+SBjJ+VUX3xXaghq9H/fg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1673301433; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=crQggRCCTS9KBx/w5xi4+o+X/zIwoXHiy4Qxywl0rDY=; b=cjhakuEtujcCDmFY4QZr2I17y5uHf1FyH/jMBZ+npa0D1+5SUnwh4QUVQlJp9sYLneLi8l J/FInu9LD+UqeiAw== To: Baoquan He , linux-kernel@vger.kernel.org Cc: x86@kernel.org, kexec@lists.infradead.org Subject: Re: kdump kernel randomly hang with tick_periodic call trace on bare metal system In-Reply-To: References: Date: Mon, 09 Jan 2023 22:57:13 +0100 Message-ID: <87mt6rjrra.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 20 2022 at 13:41, Baoquan He wrote: > On one intel bare metal system, I can randomly reproduce the kdump hang > as below with tick_periodic call trace. Attach the kernel config for > reference. This has absolutely nothing to do with x2apic IPI shorthands > [ 0.045980] Spurious LAPIC timer interrupt on cpu 0 So here the CPU receives a spurious Local APIC timer interrupt, but that's a red herring. > [ 1.152690] BUG: kernel NULL pointer dereference, address: 0000000000000088 > [ 1.159634] #PF: supervisor read access in kernel mode > [ 1.164757] #PF: error_code(0x0000) - not-present page > [ 1.169882] PGD 0 P4D 0 > [ 1.172407] Oops: 0000 [#1] PREEMPT SMP PTI > [ 1.176578] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.0.11-300.fc37.x86_64 #1 > [ 1.183870] Hardware name: Dell Inc. PowerEdge R410/0N051F, BIOS 1.11.0 07/20/2012 > [ 1.191420] RIP: 0010:tick_periodic+0x23/0x80 I'm willing to bet that this is caused by the following line in tick_periodic(): update_process_times(user_mode(get_irq_regs())); user_mode() is invoked with a NULL pointer. user_mode() accesses regs->cs. CS is at offset 0x88.... The reason for this is here: > [ 1.280648] tick_handle_periodic+0x1f/0x70 > [ 1.284821] timer_interrupt+0x14/0x20 > [ 1.288561] __handle_irq_event_percpu+0x46/0x190 > [ 1.293253] handle_irq_event+0x34/0x70 > [ 1.297080] handle_level_irq+0xa8/0x180 > [ 1.300993] resend_irqs+0x5d/0x70 > [ 1.304386] tasklet_action_common.constprop.0+0xab/0xe0 > [ 1.309686] __do_softirq+0xfb/0x319 > [ 1.313254] __irq_exit_rcu+0xd7/0x140 > [ 1.316993] common_interrupt+0xb9/0xd0 For some reason the timer interrupt is resent in software. I assume it is the HPET interrupt because that's what just got initialized. > [ 1.143537] clocksource: hpet: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 133484882848 ns and the callchain below just confirms that: > [ 1.393315] _raw_spin_unlock_irqrestore+0x19/0x40 > [ 1.398093] __setup_irq+0x443/0x6d0 > [ 1.401659] request_threaded_irq+0x109/0x170 > [ 1.406005] hpet_time_init+0x2d/0x4b > [ 1.409661] x86_late_time_init+0x17/0x34 > [ 1.413658] start_kernel+0x8cf/0x97f The software resend code does not go through the regular interrupt entry path which explains why get_irq_regs() returns NULL. That software resend is bogus especially since the timer interrupt is a level interrupt. As dmesg does not say anything about the APIC delivery mode I assume this goes through i8259, which fails to set the IRQ_LEVEL flag on all interrupt lines. The below should fix this. Thanks, tglx --- --- a/arch/x86/kernel/i8259.c +++ b/arch/x86/kernel/i8259.c @@ -114,6 +114,7 @@ static void make_8259A_irq(unsigned int disable_irq_nosync(irq); io_apic_irqs &= ~(1<init(0); - for (i = 0; i < nr_legacy_irqs(); i++) + for (i = 0; i < nr_legacy_irqs(); i++) { irq_set_chip_and_handler(i, chip, handle_level_irq); + irq_set_status_flags(i, IRQ_LEVEL); + } } void __init init_IRQ(void)