linux-stable/mm/sparse.c
Sumanth Korikkar c5f1e2d189 mm/memory_hotplug: introduce MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers
Patch series "implement "memmap on memory" feature on s390".

This series provides "memmap on memory" support on s390 platform.  "memmap
on memory" allows struct pages array to be allocated from the hotplugged
memory range instead of allocating it from main system memory.

s390 currently preallocates struct pages array for all potentially
possible memory, which ensures memory onlining always succeeds, but with
the cost of significant memory consumption from the available system
memory during boottime.  In certain extreme configuration, this could lead
to ipl failure.

"memmap on memory" ensures struct pages array are populated from self
contained hotplugged memory range instead of depleting the available
system memory and this could eliminate ipl failure on s390 platform.

On other platforms, system might go OOM when the physically hotplugged
memory depletes the available memory before it is onlined.  Hence, "memmap
on memory" feature was introduced as described in commit a08a2ae346
("mm,memory_hotplug: allocate memmap from the added memory range").

Unlike other architectures, s390 memory blocks are not physically
accessible until it is online.  To make it physically accessible two new
memory notifiers MEM_PREPARE_ONLINE / MEM_FINISH_OFFLINE are added and
this notifier lets the hypervisor inform that the memory should be made
physically accessible.  This allows for "memmap on memory" initialization
during memory hotplug onlining phase, which is performed before calling
MEM_GOING_ONLINE notifier.

Patch 1 introduces MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers
to prepare the transition of memory to and from a physically accessible
state.  New mhp_flag MHP_OFFLINE_INACCESSIBLE is introduced to ensure
altmap cannot be written when adding memory - before it is set online. 
This enhancement is crucial for implementing the "memmap on memory"
feature for s390 in a subsequent patch.

Patches 2 allocates vmemmap pages from self-contained memory range for
s390.  It allocates memory map (struct pages array) from the hotplugged
memory range, rather than using system memory by passing altmap to vmemmap
functions.

Patch 3 removes unhandled memory notifier types on s390.

Patch 4 implements MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers
on s390.  MEM_PREPARE_ONLINE memory notifier makes memory block physical
accessible via sclp assign command.  The notifier ensures self-contained
memory maps are accessible and hence enabling the "memmap on memory" on
s390.  MEM_FINISH_OFFLINE memory notifier shifts the memory block to an
inaccessible state via sclp unassign command.

Patch 5 finally enables MHP_MEMMAP_ON_MEMORY on s390.


This patch (of 5):

Introduce MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers to
prepare the transition of memory to and from a physically accessible
state.  This enhancement is crucial for implementing the "memmap on
memory" feature for s390 in a subsequent patch.

Platforms such as x86 can support physical memory hotplug via ACPI.  When
there is physical memory hotplug, ACPI event leads to the memory addition
with the following callchain:

acpi_memory_device_add()
  -> acpi_memory_enable_device()
     -> __add_memory()

After this, the hotplugged memory is physically accessible, and altmap
support prepared, before the "memmap on memory" initialization in
memory_block_online() is called.

On s390, memory hotplug works in a different way.  The available hotplug
memory has to be defined upfront in the hypervisor, but it is made
physically accessible only when the user sets it online via sysfs,
currently in the MEM_GOING_ONLINE notifier.  This is too late and "memmap
on memory" initialization is performed before calling MEM_GOING_ONLINE
notifier.

During the memory hotplug addition phase, altmap support is prepared and
during the memory onlining phase s390 requires memory to be physically
accessible and then subsequently initiate the "memmap on memory"
initialization process.

The memory provider will handle new MEM_PREPARE_ONLINE /
MEM_FINISH_OFFLINE notifications and make the memory accessible.

The mhp_flag MHP_OFFLINE_INACCESSIBLE is introduced and is relevant when
used along with MHP_MEMMAP_ON_MEMORY, because the altmap cannot be written
(e.g., poisoned) when adding memory -- before it is set online.  This
allows for adding memory with an altmap that is not currently made
available by a hypervisor.  When onlining that memory, the hypervisor can
be instructed to make that memory accessible via the new notifiers and the
onlining phase will not require any memory allocations, which is helpful
in low-memory situations.

All architectures ignore unknown memory notifiers.  Therefore, the
introduction of these new notifiers does not result in any functional
modifications across architectures.

Link: https://lkml.kernel.org/r/20240108132747.3238763-1-sumanthk@linux.ibm.com
Link: https://lkml.kernel.org/r/20240108132747.3238763-2-sumanthk@linux.ibm.com
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Suggested-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-02-21 16:00:01 -08:00

936 lines
26 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* sparse memory mappings.
*/
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/mmzone.h>
#include <linux/memblock.h>
#include <linux/compiler.h>
#include <linux/highmem.h>
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/bootmem_info.h>
#include "internal.h"
#include <asm/dma.h>
/*
* Permanent SPARSEMEM data:
*
* 1) mem_section - memory sections, mem_map's for valid memory
*/
#ifdef CONFIG_SPARSEMEM_EXTREME
struct mem_section **mem_section;
#else
struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
____cacheline_internodealigned_in_smp;
#endif
EXPORT_SYMBOL(mem_section);
#ifdef NODE_NOT_IN_PAGE_FLAGS
/*
* If we did not store the node number in the page then we have to
* do a lookup in the section_to_node_table in order to find which
* node the page belongs to.
*/
#if MAX_NUMNODES <= 256
static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
#else
static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
#endif
int page_to_nid(const struct page *page)
{
return section_to_node_table[page_to_section(page)];
}
EXPORT_SYMBOL(page_to_nid);
static void set_section_nid(unsigned long section_nr, int nid)
{
section_to_node_table[section_nr] = nid;
}
#else /* !NODE_NOT_IN_PAGE_FLAGS */
static inline void set_section_nid(unsigned long section_nr, int nid)
{
}
#endif
#ifdef CONFIG_SPARSEMEM_EXTREME
static noinline struct mem_section __ref *sparse_index_alloc(int nid)
{
struct mem_section *section = NULL;
unsigned long array_size = SECTIONS_PER_ROOT *
sizeof(struct mem_section);
if (slab_is_available()) {
section = kzalloc_node(array_size, GFP_KERNEL, nid);
} else {
section = memblock_alloc_node(array_size, SMP_CACHE_BYTES,
nid);
if (!section)
panic("%s: Failed to allocate %lu bytes nid=%d\n",
__func__, array_size, nid);
}
return section;
}
static int __meminit sparse_index_init(unsigned long section_nr, int nid)
{
unsigned long root = SECTION_NR_TO_ROOT(section_nr);
struct mem_section *section;
/*
* An existing section is possible in the sub-section hotplug
* case. First hot-add instantiates, follow-on hot-add reuses
* the existing section.
*
* The mem_hotplug_lock resolves the apparent race below.
*/
if (mem_section[root])
return 0;
section = sparse_index_alloc(nid);
if (!section)
return -ENOMEM;
mem_section[root] = section;
return 0;
}
#else /* !SPARSEMEM_EXTREME */
static inline int sparse_index_init(unsigned long section_nr, int nid)
{
return 0;
}
#endif
/*
* During early boot, before section_mem_map is used for an actual
* mem_map, we use section_mem_map to store the section's NUMA
* node. This keeps us from having to use another data structure. The
* node information is cleared just before we store the real mem_map.
*/
static inline unsigned long sparse_encode_early_nid(int nid)
{
return ((unsigned long)nid << SECTION_NID_SHIFT);
}
static inline int sparse_early_nid(struct mem_section *section)
{
return (section->section_mem_map >> SECTION_NID_SHIFT);
}
/* Validate the physical addressing limitations of the model */
static void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
unsigned long *end_pfn)
{
unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
/*
* Sanity checks - do not allow an architecture to pass
* in larger pfns than the maximum scope of sparsemem:
*/
if (*start_pfn > max_sparsemem_pfn) {
mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
"Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
*start_pfn, *end_pfn, max_sparsemem_pfn);
WARN_ON_ONCE(1);
*start_pfn = max_sparsemem_pfn;
*end_pfn = max_sparsemem_pfn;
} else if (*end_pfn > max_sparsemem_pfn) {
mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
"End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
*start_pfn, *end_pfn, max_sparsemem_pfn);
WARN_ON_ONCE(1);
*end_pfn = max_sparsemem_pfn;
}
}
/*
* There are a number of times that we loop over NR_MEM_SECTIONS,
* looking for section_present() on each. But, when we have very
* large physical address spaces, NR_MEM_SECTIONS can also be
* very large which makes the loops quite long.
*
* Keeping track of this gives us an easy way to break out of
* those loops early.
*/
unsigned long __highest_present_section_nr;
static void __section_mark_present(struct mem_section *ms,
unsigned long section_nr)
{
if (section_nr > __highest_present_section_nr)
__highest_present_section_nr = section_nr;
ms->section_mem_map |= SECTION_MARKED_PRESENT;
}
#define for_each_present_section_nr(start, section_nr) \
for (section_nr = next_present_section_nr(start-1); \
section_nr != -1; \
section_nr = next_present_section_nr(section_nr))
static inline unsigned long first_present_section_nr(void)
{
return next_present_section_nr(-1);
}
#ifdef CONFIG_SPARSEMEM_VMEMMAP
static void subsection_mask_set(unsigned long *map, unsigned long pfn,
unsigned long nr_pages)
{
int idx = subsection_map_index(pfn);
int end = subsection_map_index(pfn + nr_pages - 1);
bitmap_set(map, idx, end - idx + 1);
}
void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
{
int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
unsigned long nr, start_sec = pfn_to_section_nr(pfn);
if (!nr_pages)
return;
for (nr = start_sec; nr <= end_sec; nr++) {
struct mem_section *ms;
unsigned long pfns;
pfns = min(nr_pages, PAGES_PER_SECTION
- (pfn & ~PAGE_SECTION_MASK));
ms = __nr_to_section(nr);
subsection_mask_set(ms->usage->subsection_map, pfn, pfns);
pr_debug("%s: sec: %lu pfns: %lu set(%d, %d)\n", __func__, nr,
pfns, subsection_map_index(pfn),
subsection_map_index(pfn + pfns - 1));
pfn += pfns;
nr_pages -= pfns;
}
}
#else
void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
{
}
#endif
/* Record a memory area against a node. */
static void __init memory_present(int nid, unsigned long start, unsigned long end)
{
unsigned long pfn;
#ifdef CONFIG_SPARSEMEM_EXTREME
if (unlikely(!mem_section)) {
unsigned long size, align;
size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
align = 1 << (INTERNODE_CACHE_SHIFT);
mem_section = memblock_alloc(size, align);
if (!mem_section)
panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
__func__, size, align);
}
#endif
start &= PAGE_SECTION_MASK;
mminit_validate_memmodel_limits(&start, &end);
for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
unsigned long section = pfn_to_section_nr(pfn);
struct mem_section *ms;
sparse_index_init(section, nid);
set_section_nid(section, nid);
ms = __nr_to_section(section);
if (!ms->section_mem_map) {
ms->section_mem_map = sparse_encode_early_nid(nid) |
SECTION_IS_ONLINE;
__section_mark_present(ms, section);
}
}
}
/*
* Mark all memblocks as present using memory_present().
* This is a convenience function that is useful to mark all of the systems
* memory as present during initialization.
*/
static void __init memblocks_present(void)
{
unsigned long start, end;
int i, nid;
for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid)
memory_present(nid, start, end);
}
/*
* Subtle, we encode the real pfn into the mem_map such that
* the identity pfn - section_mem_map will return the actual
* physical page frame number.
*/
static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
{
unsigned long coded_mem_map =
(unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
BUILD_BUG_ON(SECTION_MAP_LAST_BIT > PFN_SECTION_SHIFT);
BUG_ON(coded_mem_map & ~SECTION_MAP_MASK);
return coded_mem_map;
}
#ifdef CONFIG_MEMORY_HOTPLUG
/*
* Decode mem_map from the coded memmap
*/
struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
{
/* mask off the extra low bits of information */
coded_mem_map &= SECTION_MAP_MASK;
return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
}
#endif /* CONFIG_MEMORY_HOTPLUG */
static void __meminit sparse_init_one_section(struct mem_section *ms,
unsigned long pnum, struct page *mem_map,
struct mem_section_usage *usage, unsigned long flags)
{
ms->section_mem_map &= ~SECTION_MAP_MASK;
ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum)
| SECTION_HAS_MEM_MAP | flags;
ms->usage = usage;
}
static unsigned long usemap_size(void)
{
return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
}
size_t mem_section_usage_size(void)
{
return sizeof(struct mem_section_usage) + usemap_size();
}
#ifdef CONFIG_MEMORY_HOTREMOVE
static inline phys_addr_t pgdat_to_phys(struct pglist_data *pgdat)
{
#ifndef CONFIG_NUMA
VM_BUG_ON(pgdat != &contig_page_data);
return __pa_symbol(&contig_page_data);
#else
return __pa(pgdat);
#endif
}
static struct mem_section_usage * __init
sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
unsigned long size)
{
struct mem_section_usage *usage;
unsigned long goal, limit;
int nid;
/*
* A page may contain usemaps for other sections preventing the
* page being freed and making a section unremovable while
* other sections referencing the usemap remain active. Similarly,
* a pgdat can prevent a section being removed. If section A
* contains a pgdat and section B contains the usemap, both
* sections become inter-dependent. This allocates usemaps
* from the same section as the pgdat where possible to avoid
* this problem.
*/
goal = pgdat_to_phys(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
limit = goal + (1UL << PA_SECTION_SHIFT);
nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
again:
usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, goal, limit, nid);
if (!usage && limit) {
limit = 0;
goto again;
}
return usage;
}
static void __init check_usemap_section_nr(int nid,
struct mem_section_usage *usage)
{
unsigned long usemap_snr, pgdat_snr;
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(usage) >> PAGE_SHIFT);
pgdat_snr = pfn_to_section_nr(pgdat_to_phys(pgdat) >> PAGE_SHIFT);
if (usemap_snr == pgdat_snr)
return;
if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
/* skip redundant message */
return;
old_usemap_snr = usemap_snr;
old_pgdat_snr = pgdat_snr;
usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
if (usemap_nid != nid) {
pr_info("node %d must be removed before remove section %ld\n",
nid, usemap_snr);
return;
}
/*
* There is a circular dependency.
* Some platforms allow un-removable section because they will just
* gather other removable sections for dynamic partitioning.
* Just notify un-removable section's number here.
*/
pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
usemap_snr, pgdat_snr, nid);
}
#else
static struct mem_section_usage * __init
sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
unsigned long size)
{
return memblock_alloc_node(size, SMP_CACHE_BYTES, pgdat->node_id);
}
static void __init check_usemap_section_nr(int nid,
struct mem_section_usage *usage)
{
}
#endif /* CONFIG_MEMORY_HOTREMOVE */
#ifdef CONFIG_SPARSEMEM_VMEMMAP
static unsigned long __init section_map_size(void)
{
return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
}
#else
static unsigned long __init section_map_size(void)
{
return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
}
struct page __init *__populate_section_memmap(unsigned long pfn,
unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
struct dev_pagemap *pgmap)
{
unsigned long size = section_map_size();
struct page *map = sparse_buffer_alloc(size);
phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
if (map)
return map;
map = memmap_alloc(size, size, addr, nid, false);
if (!map)
panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n",
__func__, size, PAGE_SIZE, nid, &addr);
return map;
}
#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
static void *sparsemap_buf __meminitdata;
static void *sparsemap_buf_end __meminitdata;
static inline void __meminit sparse_buffer_free(unsigned long size)
{
WARN_ON(!sparsemap_buf || size == 0);
memblock_free(sparsemap_buf, size);
}
static void __init sparse_buffer_init(unsigned long size, int nid)
{
phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
WARN_ON(sparsemap_buf); /* forgot to call sparse_buffer_fini()? */
/*
* Pre-allocated buffer is mainly used by __populate_section_memmap
* and we want it to be properly aligned to the section size - this is
* especially the case for VMEMMAP which maps memmap to PMDs
*/
sparsemap_buf = memmap_alloc(size, section_map_size(), addr, nid, true);
sparsemap_buf_end = sparsemap_buf + size;
}
static void __init sparse_buffer_fini(void)
{
unsigned long size = sparsemap_buf_end - sparsemap_buf;
if (sparsemap_buf && size > 0)
sparse_buffer_free(size);
sparsemap_buf = NULL;
}
void * __meminit sparse_buffer_alloc(unsigned long size)
{
void *ptr = NULL;
if (sparsemap_buf) {
ptr = (void *) roundup((unsigned long)sparsemap_buf, size);
if (ptr + size > sparsemap_buf_end)
ptr = NULL;
else {
/* Free redundant aligned space */
if ((unsigned long)(ptr - sparsemap_buf) > 0)
sparse_buffer_free((unsigned long)(ptr - sparsemap_buf));
sparsemap_buf = ptr + size;
}
}
return ptr;
}
void __weak __meminit vmemmap_populate_print_last(void)
{
}
/*
* Initialize sparse on a specific node. The node spans [pnum_begin, pnum_end)
* And number of present sections in this node is map_count.
*/
static void __init sparse_init_nid(int nid, unsigned long pnum_begin,
unsigned long pnum_end,
unsigned long map_count)
{
struct mem_section_usage *usage;
unsigned long pnum;
struct page *map;
usage = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nid),
mem_section_usage_size() * map_count);
if (!usage) {
pr_err("%s: node[%d] usemap allocation failed", __func__, nid);
goto failed;
}
sparse_buffer_init(map_count * section_map_size(), nid);
for_each_present_section_nr(pnum_begin, pnum) {
unsigned long pfn = section_nr_to_pfn(pnum);
if (pnum >= pnum_end)
break;
map = __populate_section_memmap(pfn, PAGES_PER_SECTION,
nid, NULL, NULL);
if (!map) {
pr_err("%s: node[%d] memory map backing failed. Some memory will not be available.",
__func__, nid);
pnum_begin = pnum;
sparse_buffer_fini();
goto failed;
}
check_usemap_section_nr(nid, usage);
sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage,
SECTION_IS_EARLY);
usage = (void *) usage + mem_section_usage_size();
}
sparse_buffer_fini();
return;
failed:
/* We failed to allocate, mark all the following pnums as not present */
for_each_present_section_nr(pnum_begin, pnum) {
struct mem_section *ms;
if (pnum >= pnum_end)
break;
ms = __nr_to_section(pnum);
ms->section_mem_map = 0;
}
}
/*
* Allocate the accumulated non-linear sections, allocate a mem_map
* for each and record the physical to section mapping.
*/
void __init sparse_init(void)
{
unsigned long pnum_end, pnum_begin, map_count = 1;
int nid_begin;
memblocks_present();
pnum_begin = first_present_section_nr();
nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
/* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
set_pageblock_order();
for_each_present_section_nr(pnum_begin + 1, pnum_end) {
int nid = sparse_early_nid(__nr_to_section(pnum_end));
if (nid == nid_begin) {
map_count++;
continue;
}
/* Init node with sections in range [pnum_begin, pnum_end) */
sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
nid_begin = nid;
pnum_begin = pnum_end;
map_count = 1;
}
/* cover the last node */
sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
vmemmap_populate_print_last();
}
#ifdef CONFIG_MEMORY_HOTPLUG
/* Mark all memory sections within the pfn range as online */
void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
unsigned long section_nr = pfn_to_section_nr(pfn);
struct mem_section *ms;
/* onlining code should never touch invalid ranges */
if (WARN_ON(!valid_section_nr(section_nr)))
continue;
ms = __nr_to_section(section_nr);
ms->section_mem_map |= SECTION_IS_ONLINE;
}
}
/* Mark all memory sections within the pfn range as offline */
void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
unsigned long section_nr = pfn_to_section_nr(pfn);
struct mem_section *ms;
/*
* TODO this needs some double checking. Offlining code makes
* sure to check pfn_valid but those checks might be just bogus
*/
if (WARN_ON(!valid_section_nr(section_nr)))
continue;
ms = __nr_to_section(section_nr);
ms->section_mem_map &= ~SECTION_IS_ONLINE;
}
}
#ifdef CONFIG_SPARSEMEM_VMEMMAP
static struct page * __meminit populate_section_memmap(unsigned long pfn,
unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
struct dev_pagemap *pgmap)
{
return __populate_section_memmap(pfn, nr_pages, nid, altmap, pgmap);
}
static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
struct vmem_altmap *altmap)
{
unsigned long start = (unsigned long) pfn_to_page(pfn);
unsigned long end = start + nr_pages * sizeof(struct page);
vmemmap_free(start, end, altmap);
}
static void free_map_bootmem(struct page *memmap)
{
unsigned long start = (unsigned long)memmap;
unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
vmemmap_free(start, end, NULL);
}
static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
{
DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
struct mem_section *ms = __pfn_to_section(pfn);
unsigned long *subsection_map = ms->usage
? &ms->usage->subsection_map[0] : NULL;
subsection_mask_set(map, pfn, nr_pages);
if (subsection_map)
bitmap_and(tmp, map, subsection_map, SUBSECTIONS_PER_SECTION);
if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
"section already deactivated (%#lx + %ld)\n",
pfn, nr_pages))
return -EINVAL;
bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
return 0;
}
static bool is_subsection_map_empty(struct mem_section *ms)
{
return bitmap_empty(&ms->usage->subsection_map[0],
SUBSECTIONS_PER_SECTION);
}
static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
{
struct mem_section *ms = __pfn_to_section(pfn);
DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
unsigned long *subsection_map;
int rc = 0;
subsection_mask_set(map, pfn, nr_pages);
subsection_map = &ms->usage->subsection_map[0];
if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
rc = -EINVAL;
else if (bitmap_intersects(map, subsection_map, SUBSECTIONS_PER_SECTION))
rc = -EEXIST;
else
bitmap_or(subsection_map, map, subsection_map,
SUBSECTIONS_PER_SECTION);
return rc;
}
#else
static struct page * __meminit populate_section_memmap(unsigned long pfn,
unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
struct dev_pagemap *pgmap)
{
return kvmalloc_node(array_size(sizeof(struct page),
PAGES_PER_SECTION), GFP_KERNEL, nid);
}
static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
struct vmem_altmap *altmap)
{
kvfree(pfn_to_page(pfn));
}
static void free_map_bootmem(struct page *memmap)
{
unsigned long maps_section_nr, removing_section_nr, i;
unsigned long magic, nr_pages;
struct page *page = virt_to_page(memmap);
nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
>> PAGE_SHIFT;
for (i = 0; i < nr_pages; i++, page++) {
magic = page->index;
BUG_ON(magic == NODE_INFO);
maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
removing_section_nr = page_private(page);
/*
* When this function is called, the removing section is
* logical offlined state. This means all pages are isolated
* from page allocator. If removing section's memmap is placed
* on the same section, it must not be freed.
* If it is freed, page allocator may allocate it which will
* be removed physically soon.
*/
if (maps_section_nr != removing_section_nr)
put_page_bootmem(page);
}
}
static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
{
return 0;
}
static bool is_subsection_map_empty(struct mem_section *ms)
{
return true;
}
static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
{
return 0;
}
#endif /* CONFIG_SPARSEMEM_VMEMMAP */
/*
* To deactivate a memory region, there are 3 cases to handle across
* two configurations (SPARSEMEM_VMEMMAP={y,n}):
*
* 1. deactivation of a partial hot-added section (only possible in
* the SPARSEMEM_VMEMMAP=y case).
* a) section was present at memory init.
* b) section was hot-added post memory init.
* 2. deactivation of a complete hot-added section.
* 3. deactivation of a complete section from memory init.
*
* For 1, when subsection_map does not empty we will not be freeing the
* usage map, but still need to free the vmemmap range.
*
* For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified
*/
static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
struct vmem_altmap *altmap)
{
struct mem_section *ms = __pfn_to_section(pfn);
bool section_is_early = early_section(ms);
struct page *memmap = NULL;
bool empty;
if (clear_subsection_map(pfn, nr_pages))
return;
empty = is_subsection_map_empty(ms);
if (empty) {
unsigned long section_nr = pfn_to_section_nr(pfn);
/*
* Mark the section invalid so that valid_section()
* return false. This prevents code from dereferencing
* ms->usage array.
*/
ms->section_mem_map &= ~SECTION_HAS_MEM_MAP;
/*
* When removing an early section, the usage map is kept (as the
* usage maps of other sections fall into the same page). It
* will be re-used when re-adding the section - which is then no
* longer an early section. If the usage map is PageReserved, it
* was allocated during boot.
*/
if (!PageReserved(virt_to_page(ms->usage))) {
kfree_rcu(ms->usage, rcu);
WRITE_ONCE(ms->usage, NULL);
}
memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
}
/*
* The memmap of early sections is always fully populated. See
* section_activate() and pfn_valid() .
*/
if (!section_is_early)
depopulate_section_memmap(pfn, nr_pages, altmap);
else if (memmap)
free_map_bootmem(memmap);
if (empty)
ms->section_mem_map = (unsigned long)NULL;
}
static struct page * __meminit section_activate(int nid, unsigned long pfn,
unsigned long nr_pages, struct vmem_altmap *altmap,
struct dev_pagemap *pgmap)
{
struct mem_section *ms = __pfn_to_section(pfn);
struct mem_section_usage *usage = NULL;
struct page *memmap;
int rc;
if (!ms->usage) {
usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
if (!usage)
return ERR_PTR(-ENOMEM);
ms->usage = usage;
}
rc = fill_subsection_map(pfn, nr_pages);
if (rc) {
if (usage)
ms->usage = NULL;
kfree(usage);
return ERR_PTR(rc);
}
/*
* The early init code does not consider partially populated
* initial sections, it simply assumes that memory will never be
* referenced. If we hot-add memory into such a section then we
* do not need to populate the memmap and can simply reuse what
* is already there.
*/
if (nr_pages < PAGES_PER_SECTION && early_section(ms))
return pfn_to_page(pfn);
memmap = populate_section_memmap(pfn, nr_pages, nid, altmap, pgmap);
if (!memmap) {
section_deactivate(pfn, nr_pages, altmap);
return ERR_PTR(-ENOMEM);
}
return memmap;
}
/**
* sparse_add_section - add a memory section, or populate an existing one
* @nid: The node to add section on
* @start_pfn: start pfn of the memory range
* @nr_pages: number of pfns to add in the section
* @altmap: alternate pfns to allocate the memmap backing store
* @pgmap: alternate compound page geometry for devmap mappings
*
* This is only intended for hotplug.
*
* Note that only VMEMMAP supports sub-section aligned hotplug,
* the proper alignment and size are gated by check_pfn_span().
*
*
* Return:
* * 0 - On success.
* * -EEXIST - Section has been present.
* * -ENOMEM - Out of memory.
*/
int __meminit sparse_add_section(int nid, unsigned long start_pfn,
unsigned long nr_pages, struct vmem_altmap *altmap,
struct dev_pagemap *pgmap)
{
unsigned long section_nr = pfn_to_section_nr(start_pfn);
struct mem_section *ms;
struct page *memmap;
int ret;
ret = sparse_index_init(section_nr, nid);
if (ret < 0)
return ret;
memmap = section_activate(nid, start_pfn, nr_pages, altmap, pgmap);
if (IS_ERR(memmap))
return PTR_ERR(memmap);
/*
* Poison uninitialized struct pages in order to catch invalid flags
* combinations.
*/
if (!altmap || !altmap->inaccessible)
page_init_poison(memmap, sizeof(struct page) * nr_pages);
ms = __nr_to_section(section_nr);
set_section_nid(section_nr, nid);
__section_mark_present(ms, section_nr);
/* Align memmap to section boundary in the subsection case */
if (section_nr_to_pfn(section_nr) != start_pfn)
memmap = pfn_to_page(section_nr_to_pfn(section_nr));
sparse_init_one_section(ms, section_nr, memmap, ms->usage, 0);
return 0;
}
void sparse_remove_section(unsigned long pfn, unsigned long nr_pages,
struct vmem_altmap *altmap)
{
struct mem_section *ms = __pfn_to_section(pfn);
if (WARN_ON_ONCE(!valid_section(ms)))
return;
section_deactivate(pfn, nr_pages, altmap);
}
#endif /* CONFIG_MEMORY_HOTPLUG */