From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752184Ab2GZKro (ORCPT ); Thu, 26 Jul 2012 06:47:44 -0400 Received: from mail7.hitachi.co.jp ([133.145.228.42]:35859 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751767Ab2GZKrn (ORCPT ); Thu, 26 Jul 2012 06:47:43 -0400 X-AuditID: b753bd60-928c4ba0000047ca-7e-5011204cdeb4 X-AuditID: b753bd60-928c4ba0000047ca-7e-5011204cdeb4 From: Tomoki Sekiyama Subject: [RESEND PATCH] x86/ioapic: Fix NULL pointer dereference on CPU hotplug after disabling irqs Cc: linux-kernel@vger.kernel.org, x86@kernel.org, yrl.pp-manager.tt@hitachi.com, Tomoki Sekiyama , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Suresh Siddha , Yinghai Lu , Alexander Gordeev Date: Thu, 26 Jul 2012 19:47:32 +0900 Message-ID: <20120726104732.2889.19144.stgit@kvmdev> In-Reply-To: <20120726102106.GA22573@gmail.com> References: <20120726102106.GA22573@gmail.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (Previous patch was broken, sorry. Resending with another mailer.) In current Linux, percpu variable `vector_irq' is not always cleared when a CPU is offlined. If the CPU that has the disabled irqs in vector_irq is hotplugged again, __setup_vector_irq() hits invalid irq vector and may crash. This bug can be reproduced as following; # echo 0 > /sys/devices/system/cpu/cpu7/online # modprobe -r some_driver_using_interrupts # vector_irq@cpu7 uncleared # echo 1 > /sys/devices/system/cpu/cpu7/online # kernel may crash To fix this problem, this patch clears vector_irq in __fixup_irqs() when the CPU is offlined. This also reverts commit f6175f5bfb4c, which partially fixes this bug by clearing vector in __clear_irq_vector(). But in environments with IOMMU IRQ remapper, it could fail because cfg->domain doesn't contain offlined CPUs. With this patch, the fix in __clear_irq_vector() can be reverted because every vector_irq is already cleared in __fixup_irqs() on offlined CPUs. Signed-off-by: Tomoki Sekiyama Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Suresh Siddha Cc: Yinghai Lu Cc: Alexander Gordeev --- arch/x86/kernel/apic/io_apic.c | 4 ++-- arch/x86/kernel/irq.c | 1 + 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 5f0ff59..ac96561 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -1195,7 +1195,7 @@ static void __clear_irq_vector(int irq, struct irq_cfg *cfg) BUG_ON(!cfg->vector); vector = cfg->vector; - for_each_cpu(cpu, cfg->domain) + for_each_cpu_and(cpu, cfg->domain, cpu_online_mask) per_cpu(vector_irq, cpu)[vector] = -1; cfg->vector = 0; @@ -1203,7 +1203,7 @@ static void __clear_irq_vector(int irq, struct irq_cfg *cfg) if (likely(!cfg->move_in_progress)) return; - for_each_cpu(cpu, cfg->old_domain) { + for_each_cpu_and(cpu, cfg->old_domain, cpu_online_mask) { for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) { if (per_cpu(vector_irq, cpu)[vector] != irq) diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 3dafc60..d27b27d 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -328,6 +328,7 @@ void fixup_irqs(void) chip->irq_retrigger(data); raw_spin_unlock(&desc->lock); } + __this_cpu_write(vector_irq[vector], -1); } } #endif