* Re: [PATCH] cxl/test: Map mock device nodes to an online node
2026-07-23 18:06 [PATCH] cxl/test: Map mock device nodes to an online node Davidlohr Bueso
@ 2026-07-23 20:44 ` Dave Jiang
2026-08-18 0:26 ` Alison Schofield
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Dave Jiang @ 2026-07-23 20:44 UTC (permalink / raw)
To: Davidlohr Bueso; +Cc: djbw, jic23, alison.schofield, linux-cxl
On 7/23/26 11:06 AM, Davidlohr Bueso wrote:
> cxl_mem_init() assigns alternating NUMA nodes to the mock memdevs
> to model multi-node topologies. On a single-node host node 1 has
> no pgdat, and the first node-aware allocation in an odd device's
> probe faults on a NULL zonelist:
>
> Oops: general protection fault, probably for non-canonical address 0xdffffc00000006e3
> KASAN: probably user-memory-access in range [0x0000000000003718-0x000000000000371f]
> Workqueue: async async_run_entry_fn
> RIP: __alloc_frozen_pages_noprof+0x288
> new_slab
> ___slab_alloc
> __kmalloc_node_track_caller_noprof
> devm_kmalloc
> cxl_mock_mem_probe
>
> Map the requested node to an online one, as dax_hmem already does
> for its target node.
>
> Fixes: cf1f6877b088 ("cxl/memdev: Add numa_node attribute")
> Fixes: e41c8452b9b2 ("tools/testing/cxl: Add a single-port host-bridge regression config")
> Fixes: c9435dbee119 ("tools/testing/cxl: Add an RCH topology")
> Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
> Found while regression testing unrelated work.
>
> tools/testing/cxl/test/cxl.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> index ef92dd35e030..5156516a82d2 100644
> --- a/tools/testing/cxl/test/cxl.c
> +++ b/tools/testing/cxl/test/cxl.c
> @@ -1748,7 +1748,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_mem;
> pdev->dev.parent = &dport->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_mem[i]);
> if (rc)
> @@ -1763,7 +1763,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_single;
> pdev->dev.parent = &dport->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_mem_single[i]);
> if (rc)
> @@ -1779,7 +1779,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_rcd;
> pdev->dev.parent = &rch->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_rcd[i]);
> if (rc)
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] cxl/test: Map mock device nodes to an online node
2026-07-23 18:06 [PATCH] cxl/test: Map mock device nodes to an online node Davidlohr Bueso
2026-07-23 20:44 ` Dave Jiang
@ 2026-08-18 0:26 ` Alison Schofield
2026-08-18 16:06 ` shaikh kamaluddin
2026-08-19 16:19 ` Gregory Price
3 siblings, 0 replies; 6+ messages in thread
From: Alison Schofield @ 2026-08-18 0:26 UTC (permalink / raw)
To: Davidlohr Bueso; +Cc: dave.jiang, djbw, jic23, linux-cxl
On Thu, Jul 23, 2026 at 11:06:30AM -0700, Davidlohr Bueso wrote:
> cxl_mem_init() assigns alternating NUMA nodes to the mock memdevs
> to model multi-node topologies. On a single-node host node 1 has
> no pgdat, and the first node-aware allocation in an odd device's
> probe faults on a NULL zonelist:
>
> Oops: general protection fault, probably for non-canonical address 0xdffffc00000006e3
> KASAN: probably user-memory-access in range [0x0000000000003718-0x000000000000371f]
> Workqueue: async async_run_entry_fn
> RIP: __alloc_frozen_pages_noprof+0x288
> new_slab
> ___slab_alloc
> __kmalloc_node_track_caller_noprof
> devm_kmalloc
> cxl_mock_mem_probe
>
> Map the requested node to an online one, as dax_hmem already does
> for its target node.
>
> Fixes: cf1f6877b088 ("cxl/memdev: Add numa_node attribute")
> Fixes: e41c8452b9b2 ("tools/testing/cxl: Add a single-port host-bridge regression config")
> Fixes: c9435dbee119 ("tools/testing/cxl: Add an RCH topology")
> Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
> ---
> Found while regression testing unrelated work.
Hi Davidlohr,
Thanks for fixing up cxl-test!
My short response is:
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Tested-by: Alison Schofield <alison.schofield@intel.com>
And the long version is, I tested this and it failed somewhere
else. I have CONFIG_PINCTRL=y so the first node aware allocation
lands in the device core, not in cxl_mock_mem_probe(). Looks like:
BUG: unable to handle page fault for address: 0000000000002d18
RIP: 0010:__alloc_frozen_pages_noprof+0x120/0x310
allocate_slab
new_slab
__slab_alloc_node
__kmalloc_node_track_caller_noprof
devm_kmalloc
pinctrl_bind_pins
really_probe
We (me) had not seen this because our cxl_test guests always have two or more
CPU-and-memory nodes, plus memory-only and nvdimm nodes on top. Node 1 is
online, so numa_map_to_online_node() is a no-op.
It reproduces with a single -numa node holding the CPUs and all memory.
That is one proximity domain, node_possible_map == {0}, no pgdat for node 1.
These settings appear as different presets for folks using run_qemu [1].
The 'tiny' option must be selected to hit this.
I'm thinking about how to work 'tiny' into the regular regression runs.
Good find Davidlohr!
-- Alison
[1] https://github.com/pmem/run_qemu
>
> tools/testing/cxl/test/cxl.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> index ef92dd35e030..5156516a82d2 100644
> --- a/tools/testing/cxl/test/cxl.c
> +++ b/tools/testing/cxl/test/cxl.c
> @@ -1748,7 +1748,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_mem;
> pdev->dev.parent = &dport->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_mem[i]);
> if (rc)
> @@ -1763,7 +1763,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_single;
> pdev->dev.parent = &dport->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_mem_single[i]);
> if (rc)
> @@ -1779,7 +1779,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_rcd;
> pdev->dev.parent = &rch->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_rcd[i]);
> if (rc)
> --
> 2.39.5
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] cxl/test: Map mock device nodes to an online node
2026-07-23 18:06 [PATCH] cxl/test: Map mock device nodes to an online node Davidlohr Bueso
2026-07-23 20:44 ` Dave Jiang
2026-08-18 0:26 ` Alison Schofield
@ 2026-08-18 16:06 ` shaikh kamaluddin
2026-08-19 16:19 ` Gregory Price
3 siblings, 0 replies; 6+ messages in thread
From: shaikh kamaluddin @ 2026-08-18 16:06 UTC (permalink / raw)
To: Davidlohr Bueso; +Cc: dave.jiang, djbw, jic23, alison.schofield, linux-cxl
On Thu, Jul 23, 2026 at 11:06:30AM -0700, Davidlohr Bueso wrote:
> cxl_mem_init() assigns alternating NUMA nodes to the mock memdevs
> to model multi-node topologies. On a single-node host node 1 has
> no pgdat, and the first node-aware allocation in an odd device's
> probe faults on a NULL zonelist:
>
> Oops: general protection fault, probably for non-canonical address 0xdffffc00000006e3
> KASAN: probably user-memory-access in range [0x0000000000003718-0x000000000000371f]
> Workqueue: async async_run_entry_fn
> RIP: __alloc_frozen_pages_noprof+0x288
> new_slab
> ___slab_alloc
> __kmalloc_node_track_caller_noprof
> devm_kmalloc
> cxl_mock_mem_probe
>
> Map the requested node to an online one, as dax_hmem already does
> for its target node.
>
> Fixes: cf1f6877b088 ("cxl/memdev: Add numa_node attribute")
> Fixes: e41c8452b9b2 ("tools/testing/cxl: Add a single-port host-bridge regression config")
> Fixes: c9435dbee119 ("tools/testing/cxl: Add an RCH topology")
> Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
> ---
> Found while regression testing unrelated work.
>
> tools/testing/cxl/test/cxl.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> index ef92dd35e030..5156516a82d2 100644
> --- a/tools/testing/cxl/test/cxl.c
> +++ b/tools/testing/cxl/test/cxl.c
> @@ -1748,7 +1748,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_mem;
> pdev->dev.parent = &dport->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_mem[i]);
> if (rc)
> @@ -1763,7 +1763,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_single;
> pdev->dev.parent = &dport->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_mem_single[i]);
> if (rc)
> @@ -1779,7 +1779,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_rcd;
> pdev->dev.parent = &rch->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_rcd[i]);
> if (rc)
> --
> 2.39.5
>
Hi Davidlohr,
I was hitting the same repeated crash while running `modprobe cxl_test` on a single-node virtme-ng guest.
For reference, the guest had only NUMA node 0 available and online:
# cat /sys/devices/system/node/possible 0 # cat /sys/devices/system/node/online 0
The crash followed the same path:
__alloc_frozen_pages_noprof new_slab ___slab_alloc __kmalloc_node_track_caller_noprof devm_kmalloc cxl_mock_mem_probe
I found this patch while looking through the linux-cxl archives and applied the same `numa_map_to_online_node()` fix to my current cxl/next tree.
The code has changed since this patch was posted. The original patch updates three sites in `cxl_mem_init()`, while current cxl/next has those corresponding sites under `cxl_type3_mem_init()`, along with a separate `cxl_type2_mem_init()` path.
After applying the equivalent changes to the three `set_dev_node()` calls in `cxl_type3_mem_init()`, the repeated crash is resolved and `modprobe cxl_test` succeeds.
I also noticed that `cxl_type2_mem_init()` now has:
set_dev_node(&pdev->dev, i % 2);
`NR_CXL_TYPE2_ACCEL` is currently 1, so this does not trigger the offline-node case today, but perhaps it would be worth using `numa_map_to_online_node()` there as well for consistency and future expansion.
Tested-by: Shaikh Kamaluddin <shaikhkamal2012@gmail.com>
Thanks,
Shaikh
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] cxl/test: Map mock device nodes to an online node
2026-07-23 18:06 [PATCH] cxl/test: Map mock device nodes to an online node Davidlohr Bueso
` (2 preceding siblings ...)
2026-08-18 16:06 ` shaikh kamaluddin
@ 2026-08-19 16:19 ` Gregory Price
2026-08-19 21:12 ` Dave Jiang
3 siblings, 1 reply; 6+ messages in thread
From: Gregory Price @ 2026-08-19 16:19 UTC (permalink / raw)
To: Davidlohr Bueso; +Cc: dave.jiang, djbw, jic23, alison.schofield, linux-cxl
On Thu, Jul 23, 2026 at 11:06:30AM -0700, Davidlohr Bueso wrote:
> cxl_mem_init() assigns alternating NUMA nodes to the mock memdevs
> to model multi-node topologies. On a single-node host node 1 has
> no pgdat, and the first node-aware allocation in an odd device's
> probe faults on a NULL zonelist:
>
> Oops: general protection fault, probably for non-canonical address 0xdffffc00000006e3
> KASAN: probably user-memory-access in range [0x0000000000003718-0x000000000000371f]
> Workqueue: async async_run_entry_fn
> RIP: __alloc_frozen_pages_noprof+0x288
> new_slab
> ___slab_alloc
> __kmalloc_node_track_caller_noprof
> devm_kmalloc
> cxl_mock_mem_probe
>
> Map the requested node to an online one, as dax_hmem already does
> for its target node.
>
> Fixes: cf1f6877b088 ("cxl/memdev: Add numa_node attribute")
> Fixes: e41c8452b9b2 ("tools/testing/cxl: Add a single-port host-bridge regression config")
> Fixes: c9435dbee119 ("tools/testing/cxl: Add an RCH topology")
I think should only have a single fixes tag? Otherwise seems it seems
unclear where/how to backport?
> Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
> ---
> Found while regression testing unrelated work.
>
> tools/testing/cxl/test/cxl.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
> index ef92dd35e030..5156516a82d2 100644
> --- a/tools/testing/cxl/test/cxl.c
> +++ b/tools/testing/cxl/test/cxl.c
> @@ -1748,7 +1748,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_mem;
> pdev->dev.parent = &dport->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_mem[i]);
> if (rc)
> @@ -1763,7 +1763,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_single;
> pdev->dev.parent = &dport->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_mem_single[i]);
> if (rc)
> @@ -1779,7 +1779,7 @@ static int cxl_mem_init(void)
> if (!pdev)
> goto err_rcd;
> pdev->dev.parent = &rch->dev;
> - set_dev_node(&pdev->dev, i % 2);
> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>
> rc = cxl_mock_platform_device_add(pdev, &cxl_rcd[i]);
> if (rc)
> --
> 2.39.5
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] cxl/test: Map mock device nodes to an online node
2026-08-19 16:19 ` Gregory Price
@ 2026-08-19 21:12 ` Dave Jiang
0 siblings, 0 replies; 6+ messages in thread
From: Dave Jiang @ 2026-08-19 21:12 UTC (permalink / raw)
To: Gregory Price, Davidlohr Bueso; +Cc: jic23, alison.schofield, linux-cxl
On 8/19/26 9:19 AM, Gregory Price wrote:
> On Thu, Jul 23, 2026 at 11:06:30AM -0700, Davidlohr Bueso wrote:
>> cxl_mem_init() assigns alternating NUMA nodes to the mock memdevs
>> to model multi-node topologies. On a single-node host node 1 has
>> no pgdat, and the first node-aware allocation in an odd device's
>> probe faults on a NULL zonelist:
>>
>> Oops: general protection fault, probably for non-canonical address 0xdffffc00000006e3
>> KASAN: probably user-memory-access in range [0x0000000000003718-0x000000000000371f]
>> Workqueue: async async_run_entry_fn
>> RIP: __alloc_frozen_pages_noprof+0x288
>> new_slab
>> ___slab_alloc
>> __kmalloc_node_track_caller_noprof
>> devm_kmalloc
>> cxl_mock_mem_probe
>>
>> Map the requested node to an online one, as dax_hmem already does
>> for its target node.
>>
>> Fixes: cf1f6877b088 ("cxl/memdev: Add numa_node attribute")
>> Fixes: e41c8452b9b2 ("tools/testing/cxl: Add a single-port host-bridge regression config")
>> Fixes: c9435dbee119 ("tools/testing/cxl: Add an RCH topology")
>
> I think should only have a single fixes tag? Otherwise seems it seems
> unclear where/how to backport?
Issues started with this commit:
Fixes: 17c38c88294d ("slab: remove cpu (partial) slabs usage from allocation paths")
But we probably should just use this:
Fixes: cf1f6877b088 ("cxl/memdev: Add numa_node attribute")
Also, this patch needs to be rebased for v7.3-rc1 due type2 changes for 7.3.
DJ
>
>> Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
>
> Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
>
>> ---
>> Found while regression testing unrelated work.
>>
>> tools/testing/cxl/test/cxl.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
>> index ef92dd35e030..5156516a82d2 100644
>> --- a/tools/testing/cxl/test/cxl.c
>> +++ b/tools/testing/cxl/test/cxl.c
>> @@ -1748,7 +1748,7 @@ static int cxl_mem_init(void)
>> if (!pdev)
>> goto err_mem;
>> pdev->dev.parent = &dport->dev;
>> - set_dev_node(&pdev->dev, i % 2);
>> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>>
>> rc = cxl_mock_platform_device_add(pdev, &cxl_mem[i]);
>> if (rc)
>> @@ -1763,7 +1763,7 @@ static int cxl_mem_init(void)
>> if (!pdev)
>> goto err_single;
>> pdev->dev.parent = &dport->dev;
>> - set_dev_node(&pdev->dev, i % 2);
>> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>>
>> rc = cxl_mock_platform_device_add(pdev, &cxl_mem_single[i]);
>> if (rc)
>> @@ -1779,7 +1779,7 @@ static int cxl_mem_init(void)
>> if (!pdev)
>> goto err_rcd;
>> pdev->dev.parent = &rch->dev;
>> - set_dev_node(&pdev->dev, i % 2);
>> + set_dev_node(&pdev->dev, numa_map_to_online_node(i % 2));
>>
>> rc = cxl_mock_platform_device_add(pdev, &cxl_rcd[i]);
>> if (rc)
>> --
>> 2.39.5
>>
>>
^ permalink raw reply [flat|nested] 6+ messages in thread