Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753462AbbHDXBe (ORCPT ); Tue, 4 Aug 2015 19:01:34 -0400 Received: from frisell.zx2c4.com ([192.95.5.64]:34780 "EHLO frisell.zx2c4.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753168AbbHDXBd (ORCPT ); Tue, 4 Aug 2015 19:01:33 -0400 MIME-Version: 1.0 In-Reply-To: <55C0F291.7060806@citrix.com> References: <55C0F291.7060806@citrix.com> Date: Wed, 5 Aug 2015 01:01:25 +0200 Message-ID: Subject: Re: [Xen-devel] printk from softirq on xen: hard lockup From: "Jason A. Donenfeld" To: David Vrabel Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, xen-devel@lists.xen.org, Paul McKenney Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1123 Lines: 30 Hey David, Sorry for the premature response on my phone earlier. Real reply follows. >> rcu_read_lock, when using Xen PV. Relevant excerpts of the > ^^ PV guest? Yes. The lockup occurs on a PV guest. Nothing special at all about the configuration. Vanilla upstream 4.1.3 kernel. >> __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? That's odd. It's a PV guest, not an HVM nor PVH guest. > > A HVM guest's serial console may be particularly slow (since it's > emulated by qemu). Try using the PV console? I am using the PV console. But actually the problem occurs too even if /proc/sys/kernel/printk is set to all zeros (no klog on the console). The plot thickens? -- 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/