["RFC PATCH" 1/2] powerpc/mm: Fix node look up with numa=off boot

[Aneesh Kumar K.V]

On 6/29/19 2:06 PM, Aneesh Kumar K.V wrote:
> If we boot with numa=off, we need to make sure we return NUMA_NO_NODE when
> looking up associativity details of resources. Without this, we hit crash
> like below
> 
> BUG: Unable to handle kernel data access at 0x40000000008
> Faulting instruction address: 0xc000000008f31704
> cpu 0x1b: Vector: 380 (Data SLB Access) at [c00000000b9bb320]
>      pc: c000000008f31704: _raw_spin_lock+0x14/0x100
>      lr: c0000000083f41fc: ____cache_alloc_node+0x5c/0x290
>      sp: c00000000b9bb5b0
>     msr: 800000010280b033
>     dar: 40000000008
>    current = 0xc00000000b9a2700
>    paca    = 0xc00000000a740c00   irqmask: 0x03   irq_happened: 0x01
>      pid   = 1, comm = swapper/27
> Linux version 5.2.0-rc4-00925-g74e188c620b1 (root at linux-d8ip) (gcc version 7.4.1 20190424 [gcc-7-branch revision 270538] (SUSE Linux)) #34 SMP Sat Jun 29 00:41:02 EDT 2019
> enter ? for help
> [link register   ] c0000000083f41fc ____cache_alloc_node+0x5c/0x290
> [c00000000b9bb5b0] 0000000000000dc0 (unreliable)
> [c00000000b9bb5f0] c0000000083f48c8 kmem_cache_alloc_node_trace+0x138/0x360
> [c00000000b9bb670] c000000008aa789c devres_alloc_node+0x4c/0xa0
> [c00000000b9bb6a0] c000000008337218 devm_memremap+0x58/0x130
> [c00000000b9bb6f0] c000000008aed00c devm_nsio_enable+0xdc/0x170
> [c00000000b9bb780] c000000008af3b6c nd_pmem_probe+0x4c/0x180
> [c00000000b9bb7b0] c000000008ad84cc nvdimm_bus_probe+0xac/0x260
> [c00000000b9bb840] c000000008aa0628 really_probe+0x148/0x500
> [c00000000b9bb8d0] c000000008aa0d7c driver_probe_device+0x19c/0x1d0
> [c00000000b9bb950] c000000008aa11bc device_driver_attach+0xcc/0x100
> [c00000000b9bb990] c000000008aa12ec __driver_attach+0xfc/0x1e0
> [c00000000b9bba10] c000000008a9d0a4 bus_for_each_dev+0xb4/0x130
> [c00000000b9bba70] c000000008a9fc04 driver_attach+0x34/0x50
> [c00000000b9bba90] c000000008a9f118 bus_add_driver+0x1d8/0x300
> [c00000000b9bbb20] c000000008aa2358 driver_register+0x98/0x1a0
> [c00000000b9bbb90] c000000008ad7e6c __nd_driver_register+0x5c/0x100
> [c00000000b9bbbf0] c0000000093efbac nd_pmem_driver_init+0x34/0x48
> [c00000000b9bbc10] c0000000080106c0 do_one_initcall+0x60/0x2d0
> [c00000000b9bbce0] c00000000938463c kernel_init_freeable+0x384/0x48c
> [c00000000b9bbdb0] c000000008010a5c kernel_init+0x2c/0x160
> [c00000000b9bbe20] c00000000800ba54 ret_from_kernel_thread+0x5c/0x68
> 
> Reported-and-debugged-by: Vaibhav Jain <vaibhav at linux.ibm.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> ---
>   arch/powerpc/mm/numa.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index 917904d2fe97..f6d68baeaa96 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -212,7 +212,7 @@ static int associativity_to_nid(const __be32 *associativity)
>   {
>   	int nid = NUMA_NO_NODE;
>   
> -	if (min_common_depth == -1)
> +	if (min_common_depth == -1 || !numa_enabled)
>   		goto out;
>   
>   	if (of_read_number(associativity, 1) >= min_common_depth)
> @@ -416,10 +416,14 @@ static int of_get_assoc_arrays(struct assoc_arrays *aa)
>   static int of_drconf_to_nid_single(struct drmem_lmb *lmb)
>   {
>   	struct assoc_arrays aa = { .arrays = NULL };
> +	/* is that correct? */
>   	int default_nid = 0;
>   	int nid = default_nid;
>   	int rc, index;
>   
> +	if (!numa_enabled)
> +		return NUMA_NO_NODE;
> +


I guess we should have here.

modified   arch/powerpc/mm/numa.c
@@ -416,12 +416,11 @@ static int of_get_assoc_arrays(struct assoc_arrays 
*aa)
  static int of_drconf_to_nid_single(struct drmem_lmb *lmb)
  {
  	struct assoc_arrays aa = { .arrays = NULL };
-	/* is that correct? */
  	int default_nid = 0;
  	int nid = default_nid;
  	int rc, index;

-	if (!numa_enabled)
+	if ((min_common_depth < 0) || !numa_enabled)
  		return NUMA_NO_NODE;

  	rc = of_get_assoc_arrays(&aa);


Nathan,

Can you check this?

>   	rc = of_get_assoc_arrays(&aa);
>   	if (rc)
>   		return default_nid;
> @@ -808,7 +812,7 @@ static void __init find_possible_nodes(void)
>   	struct device_node *rtas;
>   	u32 numnodes, i;
>   
> -	if (min_common_depth <= 0)
> +	if (min_common_depth <= 0 || !numa_enabled)
>   		return;
>   
>   	rtas = of_find_node_by_path("/rtas");
> 

-aneesh