linux-kernel - RE: [PATCH v2 1/3] x86/numa: Fix SRAT lookup of CFMWS ranges with numa_fill

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Date: Tue, 19 Mar 2024 13:15:48 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: Robert Richter <rrichter@....com>, "Rafael J. Wysocki"
	<rafael@...nel.org>, Dave Hansen <dave.hansen@...ux.intel.com>, "Andy
 Lutomirski" <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, "Thomas
 Gleixner" <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "Borislav
 Petkov" <bp@...en8.de>, <x86@...nel.org>, Dan Williams
	<dan.j.williams@...el.com>, Alison Schofield <alison.schofield@...el.com>
CC: <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-cxl@...r.kernel.org>, Robert Richter <rrichter@....com>, Derick Marks
	<derick.w.marks@...el.com>, "H. Peter Anvin" <hpa@...or.com>
Subject: RE: [PATCH v2 1/3] x86/numa: Fix SRAT lookup of CFMWS ranges with
 numa_fill_memblks()

Robert Richter wrote:
> For configurations that have the 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.
> 
> numa_fill_memblks() is implemented and used in the init section only.
> The option NUMA_KEEP_MEMINFO is only for the case when NUMA data will
> be used outside of init. So fix the SRAT lookup by moving
> numa_fill_memblks() out of the NUMA_KEEP_MEMINFO block to make it
> always available in the init section.
> 
> 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.
> 
> [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@...el.com>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Alison Schofield <alison.schofield@...el.com>
> Signed-off-by: Robert Richter <rrichter@....com>
> ---
>  arch/x86/mm/numa.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
> index 65e9a6e391c0..ce84ba86e69e 100644
> --- a/arch/x86/mm/numa.c
> +++ b/arch/x86/mm/numa.c
> @@ -929,6 +929,8 @@ int memory_add_physaddr_to_nid(u64 start)
>  }
>  EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
>  
> +#endif
> +
>  static int __init cmp_memblk(const void *a, const void *b)
>  {
>  	const struct numa_memblk *ma = *(const struct numa_memblk **)a;
> @@ -1001,5 +1003,3 @@ int __init numa_fill_memblks(u64 start, u64 end)
>  	}
>  	return 0;
>  }
> -
> -#endif

Does this achieve the goal without an additional hunk like this?

diff --git a/arch/x86/include/asm/sparsemem.h b/arch/x86/include/asm/sparsemem.h
index 1be13b2dfe8b..1aaa447ef24b 100644
--- a/arch/x86/include/asm/sparsemem.h
+++ b/arch/x86/include/asm/sparsemem.h
@@ -37,9 +37,9 @@ extern int phys_to_target_node(phys_addr_t start);
 #define phys_to_target_node phys_to_target_node
 extern int memory_add_physaddr_to_nid(u64 start);
 #define memory_add_physaddr_to_nid memory_add_physaddr_to_nid
+#endif
 extern int numa_fill_memblks(u64 start, u64 end);
 #define numa_fill_memblks numa_fill_memblks
-#endif
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_X86_SPARSEMEM_H */