From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [PATCH 4.4 26/74] x86/ioapic: Fix incorrect pointers in ioapic_setup_resources() Date: Mon, 29 Jan 2018 13:56:31 +0100 Message-ID: <20180129123848.802267981@linuxfoundation.org> References: <20180129123847.507563674@linuxfoundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <20180129123847.507563674@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rui Wang , Thomas Gleixner , tony.luck@intel.com, linux-pci@vger.kernel.org, rjw@rjwysocki.net, linux-acpi@vger.kernel.org, bhelgaas@google.com, Ingo Molnar , Joerg Roedel List-Id: linux-acpi@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rui Wang commit 9d98bcec731756b8688b59ec998707924d716d7b upstream. On a 4-socket Brickland system, hot-removing one ioapic is fine. Hot-removing the 2nd one causes panic in mp_unregister_ioapic() while calling release_resource(). It is because the iomem_res pointer has already been released when removing the first ioapic. To explain the use of &res[num] here: res is assigned to ioapic_resources, and later in ioapic_insert_resources() we do: struct resource *r = ioapic_resources; for_each_ioapic(i) { insert_resource(&iomem_resource, r); r++; } Here 'r' is treated as an arry of 'struct resource', and the r++ ensures that each element of the array is inserted separately. Thus we should call release_resouce() on each element at &res[num]. Fix it by assigning the correct pointers to ioapics[i].iomem_res in ioapic_setup_resources(). Signed-off-by: Rui Wang Signed-off-by: Thomas Gleixner Cc: tony.luck@intel.com Cc: linux-pci@vger.kernel.org Cc: rjw@rjwysocki.net Cc: linux-acpi@vger.kernel.org Cc: bhelgaas@google.com Link: http://lkml.kernel.org/r/1465369193-4816-3-git-send-email-rui.y.wang@intel.com Signed-off-by: Ingo Molnar Acked-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/apic/io_apic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -2592,8 +2592,8 @@ static struct resource * __init ioapic_s res[num].flags = IORESOURCE_MEM | IORESOURCE_BUSY; snprintf(mem, IOAPIC_RESOURCE_NAME_SIZE, "IOAPIC %u", i); mem += IOAPIC_RESOURCE_NAME_SIZE; + ioapics[i].iomem_res = &res[num]; num++; - ioapics[i].iomem_res = res; } ioapic_resources = res;