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Commit 1b000a5d authored by Mel Gorman's avatar Mel Gorman Committed by Ingo Molnar
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x86: make NUMA work on 32-bit 



The DISCONTIG memory model on x86 32 bit uses a remap allocator early
in boot. The objective is that portions of every node are mapped in to
the kernel virtual area (KVA) in place of ZONE_NORMAL so that node-local
allocations can be made for pgdat and mem_map structures.

With SPARSEMEM, the amount that is set aside is insufficient for all the
mem_maps to be allocated. During the boot process, it falls back to using
the bootmem allocator. This breaks assumptions that SPARSEMEM makes about
the layout of the mem_map in memory and results in a VM_BUG_ON triggering
due to pfn_to_page() returning garbage values.

This patch only enables the remap allocator for use with DISCONTIG.

Without SRAT support, a compile-error occurs because ACPI table parsing
functions are only available in x86-64. This patch also adds no-op stubs
and prints a warning message. What likely needs to be done is sharing
the table parsing functions between 32 and 64 bit if they are
compatible.

Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent a5ff677c

arch/x86/mm/discontig_32.c

+78 −15
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
#include <linux/kexec.h>

#include <linux/pfn.h>

#include <linux/swap.h>

#include <linux/acpi.h>



#include <asm/e820.h>

#include <asm/setup.h>
@@ -103,14 +104,10 @@ extern unsigned long highend_pfn, highstart_pfn; 


#define LARGE_PAGE_BYTES (PTRS_PER_PTE * PAGE_SIZE)



static unsigned long node_remap_start_pfn[MAX_NUMNODES];

unsigned long node_remap_size[MAX_NUMNODES];

static unsigned long node_remap_offset[MAX_NUMNODES];

static void *node_remap_start_vaddr[MAX_NUMNODES];

void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags);



static void *node_remap_end_vaddr[MAX_NUMNODES];

static void *node_remap_alloc_vaddr[MAX_NUMNODES];

static unsigned long kva_start_pfn;

static unsigned long kva_pages;

/*
@@ -167,6 +164,22 @@ static void __init allocate_pgdat(int nid) 
	}

}



#ifdef CONFIG_DISCONTIGMEM

/*

 * In the discontig memory model, a portion of the kernel virtual area (KVA)

 * is reserved and portions of nodes are mapped using it. This is to allow

 * node-local memory to be allocated for structures that would normally require

 * ZONE_NORMAL. The memory is allocated with alloc_remap() and callers

 * should be prepared to allocate from the bootmem allocator instead. This KVA

 * mechanism is incompatible with SPARSEMEM as it makes assumptions about the

 * layout of memory that are broken if alloc_remap() succeeds for some of the

 * map and fails for others

 */

static unsigned long node_remap_start_pfn[MAX_NUMNODES];

static void *node_remap_end_vaddr[MAX_NUMNODES];

static void *node_remap_alloc_vaddr[MAX_NUMNODES];

static unsigned long node_remap_offset[MAX_NUMNODES];



void *alloc_remap(int nid, unsigned long size)

{

	void *allocation = node_remap_alloc_vaddr[nid];
@@ -263,6 +276,40 @@ static unsigned long calculate_numa_remap_pages(void) 
	return reserve_pages;

}



static void init_remap_allocator(int nid)

{

	node_remap_start_vaddr[nid] = pfn_to_kaddr(

			kva_start_pfn + node_remap_offset[nid]);

	node_remap_end_vaddr[nid] = node_remap_start_vaddr[nid] +

		(node_remap_size[nid] * PAGE_SIZE);

	node_remap_alloc_vaddr[nid] = node_remap_start_vaddr[nid] +

		ALIGN(sizeof(pg_data_t), PAGE_SIZE);



	printk ("node %d will remap to vaddr %08lx - %08lx\n", nid,

		(ulong) node_remap_start_vaddr[nid],

		(ulong) pfn_to_kaddr(highstart_pfn

		   + node_remap_offset[nid] + node_remap_size[nid]));

}

#else

void *alloc_remap(int nid, unsigned long size)

{

	return NULL;

}



static unsigned long calculate_numa_remap_pages(void)

{

	return 0;

}



static void init_remap_allocator(int nid)

{

}



void __init remap_numa_kva(void)

{

}

#endif /* CONFIG_DISCONTIGMEM */



extern void setup_bootmem_allocator(void);

unsigned long __init setup_memory(void)

{
@@ -326,19 +373,9 @@ unsigned long __init setup_memory(void) 
	printk("Low memory ends at vaddr %08lx\n",

			(ulong) pfn_to_kaddr(max_low_pfn));

	for_each_online_node(nid) {

		node_remap_start_vaddr[nid] = pfn_to_kaddr(

				kva_start_pfn + node_remap_offset[nid]);

		/* Init the node remap allocator */

		node_remap_end_vaddr[nid] = node_remap_start_vaddr[nid] +

			(node_remap_size[nid] * PAGE_SIZE);

		node_remap_alloc_vaddr[nid] = node_remap_start_vaddr[nid] +

			ALIGN(sizeof(pg_data_t), PAGE_SIZE);

		init_remap_allocator(nid);



		allocate_pgdat(nid);

		printk ("node %d will remap to vaddr %08lx - %08lx\n", nid,

			(ulong) node_remap_start_vaddr[nid],

			(ulong) pfn_to_kaddr(highstart_pfn

			   + node_remap_offset[nid] + node_remap_size[nid]));

	}

	printk("High memory starts at vaddr %08lx\n",

			(ulong) pfn_to_kaddr(highstart_pfn));
@@ -439,3 +476,29 @@ int memory_add_physaddr_to_nid(u64 addr) 


EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);

#endif



#ifndef CONFIG_HAVE_ARCH_PARSE_SRAT

/*

 * XXX FIXME: Make SLIT table parsing available to 32-bit NUMA

 *

 * These stub functions are needed to compile 32-bit NUMA when SRAT is

 * not set. There are functions in srat_64.c for parsing this table

 * and it may be possible to make them common functions.

 */

void acpi_numa_slit_init (struct acpi_table_slit *slit)

{

	printk(KERN_INFO "ACPI: No support for parsing SLIT table\n");

}



void acpi_numa_processor_affinity_init (struct acpi_srat_cpu_affinity *pa)

{

}



void acpi_numa_memory_affinity_init (struct acpi_srat_mem_affinity *ma)

{

}



void acpi_numa_arch_fixup(void)

{

}

#endif /* CONFIG_HAVE_ARCH_PARSE_SRAT */