Re: [PATCH 1/3] x86/numa: Fix SRAT lookup for CFMWS ranges with numa_fill_memblks()
From: Dan Williams
Date: Mon Mar 18 2024 - 17:27:04 EST
Robert Richter wrote:
> With kconfig option NUMA_KEEP_MEMINFO disabled the SRAT lookup done
> with numa_fill_memblks() fails returning NUMA_NO_MEMBLK (-1). An
> existing SRAT memory range cannot be found for a CFMWS address range.
> This causes the addition of a duplicate numa_memblk with a different
> node id and a subsequent page fault and kernel crash during boot.
>
> Note that the issue was initially introduced with [1]. But since
> phys_to_target_node() was originally used that returned the valid node
> 0, an additional numa_memblk was not added. Though, the node id was
> wrong too.
>
> Fix this by enabling NUMA_KEEP_MEMINFO for x86 with ACPI and NUMA
> enabled.
>
> [1] fd49f99c1809 ("ACPI: NUMA: Add a node and memblk for each CFMWS not in SRAT")
>
> Fixes: 8f1004679987 ("ACPI/NUMA: Apply SRAT proximity domain to entire CFMWS window")
> Cc: Derick Marks <derick.w.marks@xxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Alison Schofield <alison.schofield@xxxxxxxxx>
> Signed-off-by: Robert Richter <rrichter@xxxxxxx>
> ---
> drivers/acpi/numa/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/acpi/numa/Kconfig b/drivers/acpi/numa/Kconfig
> index 849c2bd820b9..2f4ac6ac6768 100644
> --- a/drivers/acpi/numa/Kconfig
> +++ b/drivers/acpi/numa/Kconfig
> @@ -3,6 +3,7 @@ config ACPI_NUMA
> bool "NUMA support"
> depends on NUMA
> depends on (X86 || ARM64 || LOONGARCH)
> + select NUMA_KEEP_MEMINFO if X86
> default y if ARM64
A fix is needed, yes, but this is the wrong one. NUMA_KEEP_MEMINFO is
only about marking numa_meminfo data as not "__init". Since
numa_fill_memblks() *is* an __init function, it should have no
dependency on NUMA_KEEP_MEMINFO.
The fix here involves moving the definition of numa_fill_memblks() out
of the "#ifdef CONFIG_NUMA_KEEP_MEMINFO" in
arch/x86/include/asm/sparsemem.h so that it does not fallback to the
default definition in include/linux/numa.h.
It should also be the case that cxl_acpi needs this:
diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index 67998dbd1d46..1bf25185c35b 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -6,6 +6,7 @@ menuconfig CXL_BUS
select FW_UPLOAD
select PCI_DOE
select FIRMWARE_TABLE
+ select NUMA_KEEP_MEMINFO if NUMA
help
CXL is a bus that is electrically compatible with PCI Express, but
layers three protocols on that signalling (CXL.io, CXL.cache, and