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 E3CCEC4332F for ; Thu, 22 Dec 2022 04:12:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234938AbiLVEKG (ORCPT ); Wed, 21 Dec 2022 23:10:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43154 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229488AbiLVEKC (ORCPT ); Wed, 21 Dec 2022 23:10:02 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99B871A811 for ; Wed, 21 Dec 2022 20:09:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1671682154; 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=PZyafQqgBt7zn6f3VZzK00nebPDqAfKuXzcWmeIT/HE=; b=NtaCpndjf3mKXYgAqC3sCC9EpjHWiTEwvm4K7mgNPmXnZ6kJDQPXFxsPUFzxqUHETN4MPm AMPhEatbnY3WM/S4UMGJhielOwFKpRl2MxzUr9z0LRKin5xCls1zrGIoRQrnlx/ztCUIRe /cn5v9j9WiEiGbddwwVNMnVjxoyeUyA= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-152-8zmO4qUJPZen_wuY0c0Plg-1; Wed, 21 Dec 2022 23:09:13 -0500 X-MC-Unique: 8zmO4qUJPZen_wuY0c0Plg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id BA7311C02D35; Thu, 22 Dec 2022 04:09:09 +0000 (UTC) Received: from localhost (ovpn-12-50.pek2.redhat.com [10.72.12.50]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1672151E5; Thu, 22 Dec 2022 04:09:08 +0000 (UTC) Date: Thu, 22 Dec 2022 12:09:05 +0800 From: Baoquan He To: "Guilherme G. Piccoli" Cc: x86@kernel.org, kexec@lists.infradead.org, Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: kdump kernel randomly hang with tick_periodic call trace on bare metal system Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/21/22 at 12:46pm, Guilherme G. Piccoli wrote: > On 20/12/2022 02:51, Baoquan He wrote: > > On 12/20/22 at 01:41pm, 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. > > > > Forgot mentioning this random hang is also caused by adding > > 'nr_cpus=2' into normal kernel's cmdline, then triggering crash will get > > kdump kernel hang as below kdump log shown. > > > > The weird thing is that you seem to be using "nr_cpus=1" instead - this > is the cmdline from the log: > > "nr_cpus=2 irqpoll nr_cpus=1 reset_devices cgroup_disable=memory mce=off > numa=off udev.children-max=2 panic=10 acpi_no_memhotplug > transparent_hugepage=never nokaslr hest_disable novmcoredd cma=0 > hugetlb_cma=0 disable_cpu_apicid=16 [...]" > > You seems to pass twice the "nr_cpus" thing, and I guess kernel pick the > last one? >From the kdump kernel boot log, yes, the nr_cpus=1 is taken. The parse_early_param() will parse the kernel parameters one by one, then the last one will take effect. Here, the problem is not at nr_cpus=2 or 1, the bare metal system has 16 cpus, only 2 cpus is present, it seems to be the halted 14 cpus get wrong message and behave incorrectly to cause the issue. > > Also, what is "disable_cpu_apicid=16"? Could this be related? Not really. Please check disable_cpu_apicid in Documentation/admin-guide/kdump/kdump.rst, it's bsp's apic id.