From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934341AbZIEAdp (ORCPT ); Fri, 4 Sep 2009 20:33:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934545AbZIEAUc (ORCPT ); Fri, 4 Sep 2009 20:20:32 -0400 Received: from kroah.org ([198.145.64.141]:42048 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934544AbZIEAUa (ORCPT ); Fri, 4 Sep 2009 20:20:30 -0400 X-Mailbox-Line: From gregkh@mini.kroah.org Fri Sep 4 17:14:47 2009 Message-Id: <20090905001447.558632285@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Fri, 04 Sep 2009 17:13:39 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Mike Travis , Ingo Molnar Subject: [patch 04/71] x86: dont send an IPI to the empty set of CPUs References: <20090905001335.106974681@mini.kroah.org> Content-Disposition: inline; filename=x86-don-t-send-an-ipi-to-the-empty-set-of-cpu-s.patch In-Reply-To: <20090905001824.GA18171@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.30-stable review patch. If anyone has any objections, please let us know. ------------------ From: Linus Torvalds commit 83d349f35e1ae72268c5104dbf9ab2ae635425d4 upstream. The default_send_IPI_mask_logical() function uses the "flat" APIC mode to send an IPI to a set of CPU's at once, but if that set happens to be empty, some older local APIC's will apparently be rather unhappy. So just warn if a caller gives us an empty mask, and ignore it. This fixes a regression in 2.6.30.x, due to commit 4595f9620 ("x86: change flush_tlb_others to take a const struct cpumask"), documented here: http://bugzilla.kernel.org/show_bug.cgi?id=13933 which causes a silent lock-up. It only seems to happen on PPro, P2, P3 and Athlon XP cores. Most developers sadly (or not so sadly, if you're a developer..) have more modern CPU's. Also, on x86-64 we don't use the flat APIC mode, so it would never trigger there even if the APIC didn't like sending an empty IPI mask. Reported-by: Pavel Vilim Reported-and-tested-by: Thomas Björnell Reported-and-tested-by: Martin Rogge Cc: Mike Travis Cc: Ingo Molnar Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/apic/ipi.c | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/x86/kernel/apic/ipi.c +++ b/arch/x86/kernel/apic/ipi.c @@ -106,6 +106,9 @@ void default_send_IPI_mask_logical(const unsigned long mask = cpumask_bits(cpumask)[0]; unsigned long flags; + if (WARN_ONCE(!mask, "empty IPI mask")) + return; + local_irq_save(flags); WARN_ON(mask & ~cpumask_bits(cpu_online_mask)[0]); __default_send_IPI_dest_field(mask, vector, apic->dest_logical);