From: Rui Wang rui.y.wang@intel.com
This patch has been added to the 4.1 stable tree. If you have any objections, please let us know.
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[ Upstream commit 9d98bcec731756b8688b59ec998707924d716d7b ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/x86/kernel/apic/io_apic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index f4dc2462a1ac..484ffab4d3e8 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -2728,8 +2728,8 @@ static struct resource * __init ioapic_setup_resources(void) 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;