Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754878AbbHDROa (ORCPT ); Tue, 4 Aug 2015 13:14:30 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:48188 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753428AbbHDRO3 (ORCPT ); Tue, 4 Aug 2015 13:14:29 -0400 X-IronPort-AV: E=Sophos;i="5.15,610,1432598400"; d="scan'208";a="291221423" Message-ID: <55C0F291.7060806@citrix.com> Date: Tue, 4 Aug 2015 18:12:49 +0100 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.7.0 MIME-Version: 1.0 To: "Jason A. Donenfeld" , , , CC: Paul McKenney Subject: Re: [Xen-devel] printk from softirq on xen: hard lockup References: In-Reply-To: Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1042 Lines: 26 On 04/08/15 17:41, Jason A. Donenfeld wrote: > Hi folks, > > Paul McKenney and I had an offline discussion about some rcu questions > that eventually lead into me investigating a strange full lock-up I'm > experiencing as a consequence of a printk in softirq inside of an > rcu_read_lock, when using Xen PV. Relevant excerpts of the ^^ PV guest? > (gdb) target remote localhost:9999 > Remote debugging using localhost:9999 > __xapic_wait_icr_idle () at ./arch/x86/include/asm/ipi.h:56 > 56 while (native_apic_mem_read(APIC_ICR) & APIC_ICR_BUSY) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ => HVM guest Which is it? A HVM guest's serial console may be particularly slow (since it's emulated by qemu). Try using the PV console? David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/