This is a note to let you know that I've just added the patch titled

x86/ioapic: Fix incorrect pointers in ioapic_setup_resources()

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-ioapic-fix-incorrect-pointers-in-ioapic_setup_resources.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 9d98bcec731756b8688b59ec998707924d716d7b Mon Sep 17 00:00:00 2001

From: Rui Wang rui.y.wang@intel.com Date: Wed, 8 Jun 2016 14:59:52 +0800 Subject: x86/ioapic: Fix incorrect pointers in ioapic_setup_resources()

From: Rui Wang rui.y.wang@intel.com

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 rui.y.wang@intel.com Signed-off-by: Thomas Gleixner tglx@linutronix.de 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.c... Signed-off-by: Ingo Molnar mingo@kernel.org Acked-by: Joerg Roedel jroedel@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- 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;

Patches currently in stable-queue which might be from rui.y.wang@intel.com are

queue-4.4/x86-ioapic-fix-incorrect-pointers-in-ioapic_setup_resources.patch