[PATCH] arm64: PCI: Remove node-local allocations when initialising host controller

[jeremy.linton@arm.com (Jeremy Linton)]

Hi,

+CC Jiang Lui

On 08/01/2018 12:31 PM, Punit Agrawal wrote:
> Memory for host controller data structures is allocated local to the
> node to which the controller is associated with. This has been the
> behaviour since support for ACPI was added in
> commit 0cb0786bac15 ("ARM64: PCI: Support ACPI-based PCI host controller").

Which was apparently influenced by:

965cd0e4a5e5 x86, PCI, ACPI: Use kmalloc_node() to optimize for performance

Was there an actual use-case behind that change?

I think this fixes the immediate boot problem, but if there is any perf 
advantage it seems wise to keep it... Particularly since x86 seems to be 
doing the node sanitation in pci_acpi_root_get_node().



> 
> Drop the node local allocation as there is no benefit from doing so -
> the usage of these structures is independent from where the controller
> is located. It also causes problem during probe if the associated numa
> node hasn't been initialised due to booting with restricted cpus via
> kernel command line or where the node doesn't have cpus or memory
> associated with it.
> 
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> ---
> Hi,
> 
> This came up in the context of investigating the boot issues reported
> due to restricted cpus or buggy firmware. Part of the problem is fixed
> by Lorenzo's rework of NUMA initialisation[0].
> 
> But there also doesn't seem to be any justification for using
> node-local allocation to begin with.
> 
> Thanks,
> Punit
> 
> [0] https://patchwork.kernel.org/patch/10486001/
> 
>   arch/arm64/kernel/pci.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index 0e2ea1c78542..bb85e2f4603f 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -165,16 +165,15 @@ static void pci_acpi_generic_release_info(struct acpi_pci_root_info *ci)
>   /* Interface called from ACPI code to setup PCI host controller */
>   struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>   {
> -	int node = acpi_get_node(root->device->handle);
>   	struct acpi_pci_generic_root_info *ri;
>   	struct pci_bus *bus, *child;
>   	struct acpi_pci_root_ops *root_ops;
>   
> -	ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node);
> +	ri = kzalloc(sizeof(*ri), GFP_KERNEL);
>   	if (!ri)
>   		return NULL;
>   
> -	root_ops = kzalloc_node(sizeof(*root_ops), GFP_KERNEL, node);
> +	root_ops = kzalloc(sizeof(*root_ops), GFP_KERNEL);
>   	if (!root_ops) {
>   		kfree(ri);
>   		return NULL;
>