Contributors: 42
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| Zi Yan |
795 |
42.72% |
10 |
11.49% |
| Kamezawa Hiroyuki |
346 |
18.59% |
4 |
4.60% |
| Gerald Schaefer |
131 |
7.04% |
2 |
2.30% |
| JoonSoo Kim |
110 |
5.91% |
7 |
8.05% |
| David Hildenbrand |
74 |
3.98% |
6 |
6.90% |
| MinChan Kim |
53 |
2.85% |
2 |
2.30% |
| Johannes Weiner |
49 |
2.63% |
4 |
4.60% |
| Michal Hocko |
37 |
1.99% |
4 |
4.60% |
| Qian Cai |
33 |
1.77% |
3 |
3.45% |
| Wen Congyang |
19 |
1.02% |
1 |
1.15% |
| George G. Davis |
18 |
0.97% |
1 |
1.15% |
| Miaohe Lin |
17 |
0.91% |
2 |
2.30% |
| Naoya Horiguchi |
17 |
0.91% |
3 |
3.45% |
| Michal Nazarewicz |
16 |
0.86% |
2 |
2.30% |
| Sidhartha Kumar |
16 |
0.86% |
1 |
1.15% |
| Yasunori Goto |
12 |
0.64% |
1 |
1.15% |
| Andrew Morton |
11 |
0.59% |
2 |
2.30% |
| Bartlomiej Zolnierkiewicz |
10 |
0.54% |
3 |
3.45% |
| Andi Kleen |
10 |
0.54% |
1 |
1.15% |
| Alexander Duyck |
9 |
0.48% |
1 |
1.15% |
| Kefeng Wang |
8 |
0.43% |
3 |
3.45% |
| Xishi Qiu |
7 |
0.38% |
1 |
1.15% |
| Oscar Salvador |
6 |
0.32% |
1 |
1.15% |
| Rohit Seth |
6 |
0.32% |
1 |
1.15% |
| Fengguang Wu |
6 |
0.32% |
1 |
1.15% |
| Andy Whitcroft |
5 |
0.27% |
1 |
1.15% |
| Linus Torvalds (pre-git) |
5 |
0.27% |
3 |
3.45% |
| Wang Xiaoqiang |
4 |
0.21% |
1 |
1.15% |
| Song Muchun |
3 |
0.16% |
1 |
1.15% |
| David Howells |
3 |
0.16% |
1 |
1.15% |
| Kirill A. Shutemov |
3 |
0.16% |
1 |
1.15% |
| Vlastimil Babka |
3 |
0.16% |
2 |
2.30% |
| Mel Gorman |
3 |
0.16% |
1 |
1.15% |
| Robert Jennings |
3 |
0.16% |
1 |
1.15% |
| Matthew Wilcox |
3 |
0.16% |
1 |
1.15% |
| Dave Hansen |
3 |
0.16% |
1 |
1.15% |
| Mike Kravetz |
2 |
0.11% |
1 |
1.15% |
| Tang Chen |
1 |
0.05% |
1 |
1.15% |
| Neil Zhang |
1 |
0.05% |
1 |
1.15% |
| Maria Yu |
1 |
0.05% |
1 |
1.15% |
| Greg Kroah-Hartman |
1 |
0.05% |
1 |
1.15% |
| Liu Ping Fan |
1 |
0.05% |
1 |
1.15% |
| Total |
1861 |
|
87 |
|
// SPDX-License-Identifier: GPL-2.0
/*
* linux/mm/page_isolation.c
*/
#include <linux/mm.h>
#include <linux/page-isolation.h>
#include <linux/pageblock-flags.h>
#include <linux/memory.h>
#include <linux/hugetlb.h>
#include <linux/page_owner.h>
#include <linux/migrate.h>
#include "internal.h"
#define CREATE_TRACE_POINTS
#include <trace/events/page_isolation.h>
/*
* This function checks whether the range [start_pfn, end_pfn) includes
* unmovable pages or not. The range must fall into a single pageblock and
* consequently belong to a single zone.
*
* PageLRU check without isolation or lru_lock could race so that
* MIGRATE_MOVABLE block might include unmovable pages. And __PageMovable
* check without lock_page also may miss some movable non-lru pages at
* race condition. So you can't expect this function should be exact.
*
* Returns a page without holding a reference. If the caller wants to
* dereference that page (e.g., dumping), it has to make sure that it
* cannot get removed (e.g., via memory unplug) concurrently.
*
*/
static struct page *has_unmovable_pages(unsigned long start_pfn, unsigned long end_pfn,
int migratetype, int flags)
{
struct page *page = pfn_to_page(start_pfn);
struct zone *zone = page_zone(page);
unsigned long pfn;
VM_BUG_ON(pageblock_start_pfn(start_pfn) !=
pageblock_start_pfn(end_pfn - 1));
if (is_migrate_cma_page(page)) {
/*
* CMA allocations (alloc_contig_range) really need to mark
* isolate CMA pageblocks even when they are not movable in fact
* so consider them movable here.
*/
if (is_migrate_cma(migratetype))
return NULL;
return page;
}
for (pfn = start_pfn; pfn < end_pfn; pfn++) {
page = pfn_to_page(pfn);
/*
* Both, bootmem allocations and memory holes are marked
* PG_reserved and are unmovable. We can even have unmovable
* allocations inside ZONE_MOVABLE, for example when
* specifying "movablecore".
*/
if (PageReserved(page))
return page;
/*
* If the zone is movable and we have ruled out all reserved
* pages then it should be reasonably safe to assume the rest
* is movable.
*/
if (zone_idx(zone) == ZONE_MOVABLE)
continue;
/*
* Hugepages are not in LRU lists, but they're movable.
* THPs are on the LRU, but need to be counted as #small pages.
* We need not scan over tail pages because we don't
* handle each tail page individually in migration.
*/
if (PageHuge(page) || PageTransCompound(page)) {
struct folio *folio = page_folio(page);
unsigned int skip_pages;
if (PageHuge(page)) {
if (!hugepage_migration_supported(folio_hstate(folio)))
return page;
} else if (!folio_test_lru(folio) && !__folio_test_movable(folio)) {
return page;
}
skip_pages = folio_nr_pages(folio) - folio_page_idx(folio, page);
pfn += skip_pages - 1;
continue;
}
/*
* We can't use page_count without pin a page
* because another CPU can free compound page.
* This check already skips compound tails of THP
* because their page->_refcount is zero at all time.
*/
if (!page_ref_count(page)) {
if (PageBuddy(page))
pfn += (1 << buddy_order(page)) - 1;
continue;
}
/*
* The HWPoisoned page may be not in buddy system, and
* page_count() is not 0.
*/
if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
continue;
/*
* We treat all PageOffline() pages as movable when offlining
* to give drivers a chance to decrement their reference count
* in MEM_GOING_OFFLINE in order to indicate that these pages
* can be offlined as there are no direct references anymore.
* For actually unmovable PageOffline() where the driver does
* not support this, we will fail later when trying to actually
* move these pages that still have a reference count > 0.
* (false negatives in this function only)
*/
if ((flags & MEMORY_OFFLINE) && PageOffline(page))
continue;
if (__PageMovable(page) || PageLRU(page))
continue;
/*
* If there are RECLAIMABLE pages, we need to check
* it. But now, memory offline itself doesn't call
* shrink_node_slabs() and it still to be fixed.
*/
return page;
}
return NULL;
}
/*
* This function set pageblock migratetype to isolate if no unmovable page is
* present in [start_pfn, end_pfn). The pageblock must intersect with
* [start_pfn, end_pfn).
*/
static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags,
unsigned long start_pfn, unsigned long end_pfn)
{
struct zone *zone = page_zone(page);
struct page *unmovable;
unsigned long flags;
unsigned long check_unmovable_start, check_unmovable_end;
spin_lock_irqsave(&zone->lock, flags);
/*
* We assume the caller intended to SET migrate type to isolate.
* If it is already set, then someone else must have raced and
* set it before us.
*/
if (is_migrate_isolate_page(page)) {
spin_unlock_irqrestore(&zone->lock, flags);
return -EBUSY;
}
/*
* FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
* We just check MOVABLE pages.
*
* Pass the intersection of [start_pfn, end_pfn) and the page's pageblock
* to avoid redundant checks.
*/
check_unmovable_start = max(page_to_pfn(page), start_pfn);
check_unmovable_end = min(pageblock_end_pfn(page_to_pfn(page)),
end_pfn);
unmovable = has_unmovable_pages(check_unmovable_start, check_unmovable_end,
migratetype, isol_flags);
if (!unmovable) {
if (!move_freepages_block_isolate(zone, page, MIGRATE_ISOLATE)) {
spin_unlock_irqrestore(&zone->lock, flags);
return -EBUSY;
}
zone->nr_isolate_pageblock++;
spin_unlock_irqrestore(&zone->lock, flags);
return 0;
}
spin_unlock_irqrestore(&zone->lock, flags);
if (isol_flags & REPORT_FAILURE) {
/*
* printk() with zone->lock held will likely trigger a
* lockdep splat, so defer it here.
*/
dump_page(unmovable, "unmovable page");
}
return -EBUSY;
}
static void unset_migratetype_isolate(struct page *page, int migratetype)
{
struct zone *zone;
unsigned long flags;
bool isolated_page = false;
unsigned int order;
struct page *buddy;
zone = page_zone(page);
spin_lock_irqsave(&zone->lock, flags);
if (!is_migrate_isolate_page(page))
goto out;
/*
* Because freepage with more than pageblock_order on isolated
* pageblock is restricted to merge due to freepage counting problem,
* it is possible that there is free buddy page.
* move_freepages_block() doesn't care of merge so we need other
* approach in order to merge them. Isolation and free will make
* these pages to be merged.
*/
if (PageBuddy(page)) {
order = buddy_order(page);
if (order >= pageblock_order && order < MAX_PAGE_ORDER) {
buddy = find_buddy_page_pfn(page, page_to_pfn(page),
order, NULL);
if (buddy && !is_migrate_isolate_page(buddy)) {
isolated_page = !!__isolate_free_page(page, order);
/*
* Isolating a free page in an isolated pageblock
* is expected to always work as watermarks don't
* apply here.
*/
VM_WARN_ON(!isolated_page);
}
}
}
/*
* If we isolate freepage with more than pageblock_order, there
* should be no freepage in the range, so we could avoid costly
* pageblock scanning for freepage moving.
*
* We didn't actually touch any of the isolated pages, so place them
* to the tail of the freelist. This is an optimization for memory
* onlining - just onlined memory won't immediately be considered for
* allocation.
*/
if (!isolated_page) {
/*
* Isolating this block already succeeded, so this
* should not fail on zone boundaries.
*/
WARN_ON_ONCE(!move_freepages_block_isolate(zone, page, migratetype));
} else {
set_pageblock_migratetype(page, migratetype);
__putback_isolated_page(page, order, migratetype);
}
zone->nr_isolate_pageblock--;
out:
spin_unlock_irqrestore(&zone->lock, flags);
}
static inline struct page *
__first_valid_page(unsigned long pfn, unsigned long nr_pages)
{
int i;
for (i = 0; i < nr_pages; i++) {
struct page *page;
page = pfn_to_online_page(pfn + i);
if (!page)
continue;
return page;
}
return NULL;
}
/**
* isolate_single_pageblock() -- tries to isolate a pageblock that might be
* within a free or in-use page.
* @boundary_pfn: pageblock-aligned pfn that a page might cross
* @flags: isolation flags
* @gfp_flags: GFP flags used for migrating pages
* @isolate_before: isolate the pageblock before the boundary_pfn
* @skip_isolation: the flag to skip the pageblock isolation in second
* isolate_single_pageblock()
* @migratetype: migrate type to set in error recovery.
*
* Free and in-use pages can be as big as MAX_PAGE_ORDER and contain more than one
* pageblock. When not all pageblocks within a page are isolated at the same
* time, free page accounting can go wrong. For example, in the case of
* MAX_PAGE_ORDER = pageblock_order + 1, a MAX_PAGE_ORDER page has two
* pagelbocks.
* [ MAX_PAGE_ORDER ]
* [ pageblock0 | pageblock1 ]
* When either pageblock is isolated, if it is a free page, the page is not
* split into separate migratetype lists, which is supposed to; if it is an
* in-use page and freed later, __free_one_page() does not split the free page
* either. The function handles this by splitting the free page or migrating
* the in-use page then splitting the free page.
*/
static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
gfp_t gfp_flags, bool isolate_before, bool skip_isolation,
int migratetype)
{
unsigned long start_pfn;
unsigned long isolate_pageblock;
unsigned long pfn;
struct zone *zone;
int ret;
VM_BUG_ON(!pageblock_aligned(boundary_pfn));
if (isolate_before)
isolate_pageblock = boundary_pfn - pageblock_nr_pages;
else
isolate_pageblock = boundary_pfn;
/*
* scan at the beginning of MAX_ORDER_NR_PAGES aligned range to avoid
* only isolating a subset of pageblocks from a bigger than pageblock
* free or in-use page. Also make sure all to-be-isolated pageblocks
* are within the same zone.
*/
zone = page_zone(pfn_to_page(isolate_pageblock));
start_pfn = max(ALIGN_DOWN(isolate_pageblock, MAX_ORDER_NR_PAGES),
zone->zone_start_pfn);
if (skip_isolation) {
int mt __maybe_unused = get_pageblock_migratetype(pfn_to_page(isolate_pageblock));
VM_BUG_ON(!is_migrate_isolate(mt));
} else {
ret = set_migratetype_isolate(pfn_to_page(isolate_pageblock), migratetype,
flags, isolate_pageblock, isolate_pageblock + pageblock_nr_pages);
if (ret)
return ret;
}
/*
* Bail out early when the to-be-isolated pageblock does not form
* a free or in-use page across boundary_pfn:
*
* 1. isolate before boundary_pfn: the page after is not online
* 2. isolate after boundary_pfn: the page before is not online
*
* This also ensures correctness. Without it, when isolate after
* boundary_pfn and [start_pfn, boundary_pfn) are not online,
* __first_valid_page() will return unexpected NULL in the for loop
* below.
*/
if (isolate_before) {
if (!pfn_to_online_page(boundary_pfn))
return 0;
} else {
if (!pfn_to_online_page(boundary_pfn - 1))
return 0;
}
for (pfn = start_pfn; pfn < boundary_pfn;) {
struct page *page = __first_valid_page(pfn, boundary_pfn - pfn);
VM_BUG_ON(!page);
pfn = page_to_pfn(page);
if (PageBuddy(page)) {
int order = buddy_order(page);
/* move_freepages_block_isolate() handled this */
VM_WARN_ON_ONCE(pfn + (1 << order) > boundary_pfn);
pfn += 1UL << order;
continue;
}
/*
* If a compound page is straddling our block, attempt
* to migrate it out of the way.
*
* We don't have to worry about this creating a large
* free page that straddles into our block: gigantic
* pages are freed as order-0 chunks, and LRU pages
* (currently) do not exceed pageblock_order.
*
* The block of interest has already been marked
* MIGRATE_ISOLATE above, so when migration is done it
* will free its pages onto the correct freelists.
*/
if (PageCompound(page)) {
struct page *head = compound_head(page);
unsigned long head_pfn = page_to_pfn(head);
unsigned long nr_pages = compound_nr(head);
if (head_pfn + nr_pages <= boundary_pfn) {
pfn = head_pfn + nr_pages;
continue;
}
#if defined CONFIG_COMPACTION || defined CONFIG_CMA
if (PageHuge(page)) {
int page_mt = get_pageblock_migratetype(page);
struct compact_control cc = {
.nr_migratepages = 0,
.order = -1,
.zone = page_zone(pfn_to_page(head_pfn)),
.mode = MIGRATE_SYNC,
.ignore_skip_hint = true,
.no_set_skip_hint = true,
.gfp_mask = gfp_flags,
.alloc_contig = true,
};
INIT_LIST_HEAD(&cc.migratepages);
ret = __alloc_contig_migrate_range(&cc, head_pfn,
head_pfn + nr_pages, page_mt);
if (ret)
goto failed;
pfn = head_pfn + nr_pages;
continue;
}
/*
* These pages are movable too, but they're
* not expected to exceed pageblock_order.
*
* Let us know when they do, so we can add
* proper free and split handling for them.
*/
VM_WARN_ON_ONCE_PAGE(PageLRU(page), page);
VM_WARN_ON_ONCE_PAGE(__PageMovable(page), page);
#endif
goto failed;
}
pfn++;
}
return 0;
failed:
/* restore the original migratetype */
if (!skip_isolation)
unset_migratetype_isolate(pfn_to_page(isolate_pageblock), migratetype);
return -EBUSY;
}
/**
* start_isolate_page_range() - mark page range MIGRATE_ISOLATE
* @start_pfn: The first PFN of the range to be isolated.
* @end_pfn: The last PFN of the range to be isolated.
* @migratetype: Migrate type to set in error recovery.
* @flags: The following flags are allowed (they can be combined in
* a bit mask)
* MEMORY_OFFLINE - isolate to offline (!allocate) memory
* e.g., skip over PageHWPoison() pages
* and PageOffline() pages.
* REPORT_FAILURE - report details about the failure to
* isolate the range
* @gfp_flags: GFP flags used for migrating pages that sit across the
* range boundaries.
*
* Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
* the range will never be allocated. Any free pages and pages freed in the
* future will not be allocated again. If specified range includes migrate types
* other than MOVABLE or CMA, this will fail with -EBUSY. For isolating all
* pages in the range finally, the caller have to free all pages in the range.
* test_page_isolated() can be used for test it.
*
* The function first tries to isolate the pageblocks at the beginning and end
* of the range, since there might be pages across the range boundaries.
* Afterwards, it isolates the rest of the range.
*
* There is no high level synchronization mechanism that prevents two threads
* from trying to isolate overlapping ranges. If this happens, one thread
* will notice pageblocks in the overlapping range already set to isolate.
* This happens in set_migratetype_isolate, and set_migratetype_isolate
* returns an error. We then clean up by restoring the migration type on
* pageblocks we may have modified and return -EBUSY to caller. This
* prevents two threads from simultaneously working on overlapping ranges.
*
* Please note that there is no strong synchronization with the page allocator
* either. Pages might be freed while their page blocks are marked ISOLATED.
* A call to drain_all_pages() after isolation can flush most of them. However
* in some cases pages might still end up on pcp lists and that would allow
* for their allocation even when they are in fact isolated already. Depending
* on how strong of a guarantee the caller needs, zone_pcp_disable/enable()
* might be used to flush and disable pcplist before isolation and enable after
* unisolation.
*
* Return: 0 on success and -EBUSY if any part of range cannot be isolated.
*/
int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
int migratetype, int flags, gfp_t gfp_flags)
{
unsigned long pfn;
struct page *page;
/* isolation is done at page block granularity */
unsigned long isolate_start = pageblock_start_pfn(start_pfn);
unsigned long isolate_end = pageblock_align(end_pfn);
int ret;
bool skip_isolation = false;
/* isolate [isolate_start, isolate_start + pageblock_nr_pages) pageblock */
ret = isolate_single_pageblock(isolate_start, flags, gfp_flags, false,
skip_isolation, migratetype);
if (ret)
return ret;
if (isolate_start == isolate_end - pageblock_nr_pages)
skip_isolation = true;
/* isolate [isolate_end - pageblock_nr_pages, isolate_end) pageblock */
ret = isolate_single_pageblock(isolate_end, flags, gfp_flags, true,
skip_isolation, migratetype);
if (ret) {
unset_migratetype_isolate(pfn_to_page(isolate_start), migratetype);
return ret;
}
/* skip isolated pageblocks at the beginning and end */
for (pfn = isolate_start + pageblock_nr_pages;
pfn < isolate_end - pageblock_nr_pages;
pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
if (page && set_migratetype_isolate(page, migratetype, flags,
start_pfn, end_pfn)) {
undo_isolate_page_range(isolate_start, pfn, migratetype);
unset_migratetype_isolate(
pfn_to_page(isolate_end - pageblock_nr_pages),
migratetype);
return -EBUSY;
}
}
return 0;
}
/**
* undo_isolate_page_range - undo effects of start_isolate_page_range()
* @start_pfn: The first PFN of the isolated range
* @end_pfn: The last PFN of the isolated range
* @migratetype: New migrate type to set on the range
*
* This finds every MIGRATE_ISOLATE page block in the given range
* and switches it to @migratetype.
*/
void undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
int migratetype)
{
unsigned long pfn;
struct page *page;
unsigned long isolate_start = pageblock_start_pfn(start_pfn);
unsigned long isolate_end = pageblock_align(end_pfn);
for (pfn = isolate_start;
pfn < isolate_end;
pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
if (!page || !is_migrate_isolate_page(page))
continue;
unset_migratetype_isolate(page, migratetype);
}
}
/*
* Test all pages in the range is free(means isolated) or not.
* all pages in [start_pfn...end_pfn) must be in the same zone.
* zone->lock must be held before call this.
*
* Returns the last tested pfn.
*/
static unsigned long
__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
int flags)
{
struct page *page;
while (pfn < end_pfn) {
page = pfn_to_page(pfn);
if (PageBuddy(page))
/*
* If the page is on a free list, it has to be on
* the correct MIGRATE_ISOLATE freelist. There is no
* simple way to verify that as VM_BUG_ON(), though.
*/
pfn += 1 << buddy_order(page);
else if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
/* A HWPoisoned page cannot be also PageBuddy */
pfn++;
else if ((flags & MEMORY_OFFLINE) && PageOffline(page) &&
!page_count(page))
/*
* The responsible driver agreed to skip PageOffline()
* pages when offlining memory by dropping its
* reference in MEM_GOING_OFFLINE.
*/
pfn++;
else
break;
}
return pfn;
}
/**
* test_pages_isolated - check if pageblocks in range are isolated
* @start_pfn: The first PFN of the isolated range
* @end_pfn: The first PFN *after* the isolated range
* @isol_flags: Testing mode flags
*
* This tests if all in the specified range are free.
*
* If %MEMORY_OFFLINE is specified in @flags, it will consider
* poisoned and offlined pages free as well.
*
* Caller must ensure the requested range doesn't span zones.
*
* Returns 0 if true, -EBUSY if one or more pages are in use.
*/
int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
int isol_flags)
{
unsigned long pfn, flags;
struct page *page;
struct zone *zone;
int ret;
/*
* Note: pageblock_nr_pages != MAX_PAGE_ORDER. Then, chunks of free
* pages are not aligned to pageblock_nr_pages.
* Then we just check migratetype first.
*/
for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
if (page && !is_migrate_isolate_page(page))
break;
}
page = __first_valid_page(start_pfn, end_pfn - start_pfn);
if ((pfn < end_pfn) || !page) {
ret = -EBUSY;
goto out;
}
/* Check all pages are free or marked as ISOLATED */
zone = page_zone(page);
spin_lock_irqsave(&zone->lock, flags);
pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, isol_flags);
spin_unlock_irqrestore(&zone->lock, flags);
ret = pfn < end_pfn ? -EBUSY : 0;
out:
trace_test_pages_isolated(start_pfn, end_pfn, pfn);
return ret;
}