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mm: Convert page migration to XArray

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Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2017-12-04 04:35:16 -05:00
parent 560d454bae
commit 89eb946a74
1 changed files with 18 additions and 30 deletions
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48
mm/migrate.c
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@ -323,7 +323,7 @@ void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
page = migration_entry_to_page(entry);
/*
* Once radix-tree replacement of page migration started, page_count
* Once page cache replacement of page migration started, page_count
* *must* be zero. And, we don't want to call wait_on_page_locked()
* against a page without get_page().
* So, we use get_page_unless_zero(), here. Even failed, page fault
@ -438,10 +438,10 @@ int migrate_page_move_mapping(struct address_space *mapping,
struct buffer_head *head, enum migrate_mode mode,
int extra_count)
{
XA_STATE(xas, &mapping->i_pages, page_index(page));
struct zone *oldzone, *newzone;
int dirty;
int expected_count = 1 + extra_count;
void **pslot;
/*
* Device public or private pages have an extra refcount as they are
@ -467,21 +467,16 @@ int migrate_page_move_mapping(struct address_space *mapping,
oldzone = page_zone(page);
newzone = page_zone(newpage);
xa_lock_irq(&mapping->i_pages);
pslot = radix_tree_lookup_slot(&mapping->i_pages,
page_index(page));
xas_lock_irq(&xas);
expected_count += hpage_nr_pages(page) + page_has_private(page);
if (page_count(page) != expected_count ||
radix_tree_deref_slot_protected(pslot,
&mapping->i_pages.xa_lock) != page) {
xa_unlock_irq(&mapping->i_pages);
if (page_count(page) != expected_count || xas_load(&xas) != page) {
xas_unlock_irq(&xas);
return -EAGAIN;
}
if (!page_ref_freeze(page, expected_count)) {
xa_unlock_irq(&mapping->i_pages);
xas_unlock_irq(&xas);
return -EAGAIN;
}
@ -495,7 +490,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
if (mode == MIGRATE_ASYNC && head &&
!buffer_migrate_lock_buffers(head, mode)) {
page_ref_unfreeze(page, expected_count);
xa_unlock_irq(&mapping->i_pages);
xas_unlock_irq(&xas);
return -EAGAIN;
}
@ -523,16 +518,13 @@ int migrate_page_move_mapping(struct address_space *mapping,
SetPageDirty(newpage);
}
radix_tree_replace_slot(&mapping->i_pages, pslot, newpage);
xas_store(&xas, newpage);
if (PageTransHuge(page)) {
int i;
int index = page_index(page);
for (i = 1; i < HPAGE_PMD_NR; i++) {
pslot = radix_tree_lookup_slot(&mapping->i_pages,
index + i);
radix_tree_replace_slot(&mapping->i_pages, pslot,
newpage + i);
xas_next(&xas);
xas_store(&xas, newpage + i);
}
}
@ -543,7 +535,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
*/
page_ref_unfreeze(page, expected_count - hpage_nr_pages(page));
xa_unlock(&mapping->i_pages);
xas_unlock(&xas);
/* Leave irq disabled to prevent preemption while updating stats */
/*
@ -583,22 +575,18 @@ EXPORT_SYMBOL(migrate_page_move_mapping);
int migrate_huge_page_move_mapping(struct address_space *mapping,
struct page *newpage, struct page *page)
{
XA_STATE(xas, &mapping->i_pages, page_index(page));
int expected_count;
void **pslot;
xa_lock_irq(&mapping->i_pages);
pslot = radix_tree_lookup_slot(&mapping->i_pages, page_index(page));
xas_lock_irq(&xas);
expected_count = 2 + page_has_private(page);
if (page_count(page) != expected_count ||
radix_tree_deref_slot_protected(pslot, &mapping->i_pages.xa_lock) != page) {
xa_unlock_irq(&mapping->i_pages);
if (page_count(page) != expected_count || xas_load(&xas) != page) {
xas_unlock_irq(&xas);
return -EAGAIN;
}
if (!page_ref_freeze(page, expected_count)) {
xa_unlock_irq(&mapping->i_pages);
xas_unlock_irq(&xas);
return -EAGAIN;
}
@ -607,11 +595,11 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
get_page(newpage);
radix_tree_replace_slot(&mapping->i_pages, pslot, newpage);
xas_store(&xas, newpage);
page_ref_unfreeze(page, expected_count - 1);
xa_unlock_irq(&mapping->i_pages);
xas_unlock_irq(&xas);
return MIGRATEPAGE_SUCCESS;
}