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mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y

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Size of the mem_section[] array depends on the size of the physical address space.

In preparation for boot-time switching between paging modes on x86-64
we need to make the allocation of mem_section[] dynamic, because otherwise
we waste a lot of RAM: with CONFIG_NODE_SHIFT=10, mem_section[] size is 32kB
for 4-level paging and 2MB for 5-level paging mode.

The patch allocates the array on the first call to sparse_memory_present_with_active_regions().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@suse.de>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170929140821.37654-2-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Kirill A. Shutemov 2017-09-29 17:08:16 +03:00 committed by Ingo Molnar
parent 967535223f
commit 83e3c48729
3 changed files with 26 additions and 7 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

6
include/linux/mmzone.h
View file

@ -1150,13 +1150,17 @@ struct mem_section {
#define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1)
#ifdef CONFIG_SPARSEMEM_EXTREME
extern struct mem_section *mem_section[NR_SECTION_ROOTS];
extern struct mem_section **mem_section;
#else
extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
#endif
static inline struct mem_section *__nr_to_section(unsigned long nr)
{
#ifdef CONFIG_SPARSEMEM_EXTREME
if (!mem_section)
return NULL;
#endif
if (!mem_section[SECTION_NR_TO_ROOT(nr)])
return NULL;
return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];

10
mm/page_alloc.c
View file

@ -5646,6 +5646,16 @@ void __init sparse_memory_present_with_active_regions(int nid)
unsigned long start_pfn, end_pfn;
int i, this_nid;
#ifdef CONFIG_SPARSEMEM_EXTREME
if (!mem_section) {
unsigned long size, align;
size = sizeof(struct mem_section) * NR_SECTION_ROOTS;
align = 1 << (INTERNODE_CACHE_SHIFT);
mem_section = memblock_virt_alloc(size, align);
}
#endif
for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, &this_nid)
memory_present(this_nid, start_pfn, end_pfn);
}

17
mm/sparse.c
View file

@ -22,8 +22,7 @@
* 1) mem_section - memory sections, mem_map's for valid memory
*/
#ifdef CONFIG_SPARSEMEM_EXTREME
struct mem_section *mem_section[NR_SECTION_ROOTS]
____cacheline_internodealigned_in_smp;
struct mem_section **mem_section;
#else
struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
____cacheline_internodealigned_in_smp;
@ -100,7 +99,7 @@ static inline int sparse_index_init(unsigned long section_nr, int nid)
int __section_nr(struct mem_section* ms)
{
unsigned long root_nr;
struct mem_section* root;
struct mem_section *root = NULL;
for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
@ -111,7 +110,7 @@ int __section_nr(struct mem_section* ms)
break;
}
VM_BUG_ON(root_nr == NR_SECTION_ROOTS);
VM_BUG_ON(!root);
return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
}
@ -329,11 +328,17 @@ sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
{
unsigned long usemap_snr, pgdat_snr;
static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
static unsigned long old_usemap_snr;
static unsigned long old_pgdat_snr;
struct pglist_data *pgdat = NODE_DATA(nid);
int usemap_nid;
/* First call */
if (!old_usemap_snr) {
old_usemap_snr = NR_MEM_SECTIONS;
old_pgdat_snr = NR_MEM_SECTIONS;
}
usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
if (usemap_snr == pgdat_snr)