Re: [PATCH v11 23/23] CXL/PCI: Disable CXL protocol error interrupts during CXL Port cleanup

Gregory Price
2025-09-10T15:07:51Z

Hi Terry,

On Tue, Aug 26, 2025 at 08:35:38PM -0500, Terry Bowman wrote:
> Introduce cxl_mask_proto_interrupts() to call pci_aer_mask_internal_errors().
> Add calls to cxl_mask_proto_interrupts() within CXL Port teardown for CXL
> Root Ports, CXL Downstream Switch Ports, CXL Upstream Switch Ports, and CXL
> Endpoints. Follow the same "bottom-up" approach used during CXL Port
> teardown.
>
...
> @@ -1471,6 +1475,8 @@ static void cxl_detach_ep(void *data)
> {
> struct cxl_memdev *cxlmd = data;
>
> + cxl_mask_proto_interrupts(cxlmd->cxlds->dev);
> +
> for (int i = cxlmd->depth - 1; i >= 1; i--) {
> struct cxl_port *port, *parent_port;
> struct detach_ctx ctx = {

While testing v10 of this patch set, we found ourselves with a deadlock
on boot with the following stack in the hung task:

[ 252.784440] <TASK>
[ 252.789090] schedule+0x5d6/0x1670
[ 252.796629] ? schedule_preempt_disabled+0xa/0x10
[ 252.807061] schedule_preempt_disabled+0xa/0x10
[ 252.817108] __mutex_lock+0x245/0x7b0
[ 252.825229] cxl_mask_proto_interrupts+0x23/0x50
[ 252.835470] cxl_detach_ep+0x25/0x2e0

This occurs on a system which fails to probe ports fully due to the
duplicate id error resolved by the Delayed HB patch set.

But it's concerning that there's a deadlock condition without that
patch set. Can you help try to eyeball this? I'm trying to get more
debug info, but testing system availability is limited.

~Gregory