/*
* 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
- * will occur again.
+ * is zero; but we must not call put_and_wait_on_page_locked() without
+ * a ref. Use get_page_unless_zero(), and just fault again if it fails.
*/
if (!get_page_unless_zero(page))
goto out;
pte_unmap_unlock(ptep, ptl);
- wait_on_page_locked(page);
- put_page(page);
+ put_and_wait_on_page_locked(page);
return;
out:
pte_unmap_unlock(ptep, ptl);
if (!get_page_unless_zero(page))
goto unlock;
spin_unlock(ptl);
- wait_on_page_locked(page);
- put_page(page);
+ put_and_wait_on_page_locked(page);
return;
unlock:
spin_unlock(ptl);
}
#endif /* CONFIG_BLOCK */
+static int expected_page_refs(struct page *page)
+{
+ int expected_count = 1;
+
+ /*
+ * Device public or private pages have an extra refcount as they are
+ * ZONE_DEVICE pages.
+ */
+ expected_count += is_device_private_page(page);
+ expected_count += is_device_public_page(page);
+ if (page_mapping(page))
+ expected_count += hpage_nr_pages(page) + page_has_private(page);
+
+ return expected_count;
+}
+
/*
* Replace the page in the mapping.
*
XA_STATE(xas, &mapping->i_pages, page_index(page));
struct zone *oldzone, *newzone;
int dirty;
- int expected_count = 1 + extra_count;
-
- /*
- * Device public or private pages have an extra refcount as they are
- * ZONE_DEVICE pages.
- */
- expected_count += is_device_private_page(page);
- expected_count += is_device_public_page(page);
+ int expected_count = expected_page_refs(page) + extra_count;
if (!mapping) {
/* Anonymous page without mapping */
newzone = page_zone(newpage);
xas_lock_irq(&xas);
-
- expected_count += hpage_nr_pages(page) + page_has_private(page);
if (page_count(page) != expected_count || xas_load(&xas) != page) {
xas_unlock_irq(&xas);
return -EAGAIN;
}
/*
- * In the async migration case of moving a page with buffers, lock the
- * buffers using trylock before the mapping is moved. If the mapping
- * was moved, we later failed to lock the buffers and could not move
- * the mapping back due to an elevated page count, we would have to
- * block waiting on other references to be dropped.
- */
- if (mode == MIGRATE_ASYNC && head &&
- !buffer_migrate_lock_buffers(head, mode)) {
- page_ref_unfreeze(page, expected_count);
- xas_unlock_irq(&xas);
- return -EAGAIN;
- }
-
- /*
* Now we know that no one else is looking at the page:
* no turning back from here.
*/
{
struct buffer_head *bh, *head;
int rc;
+ int expected_count;
if (!page_has_buffers(page))
return migrate_page(mapping, newpage, page, mode);
- head = page_buffers(page);
+ /* Check whether page does not have extra refs before we do more work */
+ expected_count = expected_page_refs(page);
+ if (page_count(page) != expected_count)
+ return -EAGAIN;
- rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0);
+ head = page_buffers(page);
+ if (!buffer_migrate_lock_buffers(head, mode))
+ return -EAGAIN;
+ rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
if (rc != MIGRATEPAGE_SUCCESS)
- return rc;
-
- /*
- * In the async case, migrate_page_move_mapping locked the buffers
- * with an IRQ-safe spinlock held. In the sync case, the buffers
- * need to be locked now
- */
- if (mode != MIGRATE_ASYNC)
- BUG_ON(!buffer_migrate_lock_buffers(head, mode));
+ goto unlock_buffers;
ClearPagePrivate(page);
set_page_private(newpage, page_private(page));
else
migrate_page_states(newpage, page);
+ rc = MIGRATEPAGE_SUCCESS;
+unlock_buffers:
bh = head;
do {
unlock_buffer(bh);
} while (bh != head);
- return MIGRATEPAGE_SUCCESS;
+ return rc;
}
EXPORT_SYMBOL(buffer_migrate_page);
#endif
*/
static void migrate_vma_collect(struct migrate_vma *migrate)
{
+ struct mmu_notifier_range range;
struct mm_walk mm_walk;
mm_walk.pmd_entry = migrate_vma_collect_pmd;
mm_walk.mm = migrate->vma->vm_mm;
mm_walk.private = migrate;
- mmu_notifier_invalidate_range_start(mm_walk.mm,
- migrate->start,
- migrate->end);
+ mmu_notifier_range_init(&range, mm_walk.mm, migrate->start,
+ migrate->end);
+ mmu_notifier_invalidate_range_start(&range);
walk_page_range(migrate->start, migrate->end, &mm_walk);
- mmu_notifier_invalidate_range_end(mm_walk.mm,
- migrate->start,
- migrate->end);
+ mmu_notifier_invalidate_range_end(&range);
migrate->end = migrate->start + (migrate->npages << PAGE_SHIFT);
}
{
const unsigned long npages = migrate->npages;
const unsigned long start = migrate->start;
- struct vm_area_struct *vma = migrate->vma;
- struct mm_struct *mm = vma->vm_mm;
- unsigned long addr, i, mmu_start;
+ struct mmu_notifier_range range;
+ unsigned long addr, i;
bool notified = false;
for (i = 0, addr = start; i < npages; addr += PAGE_SIZE, i++) {
continue;
}
if (!notified) {
- mmu_start = addr;
notified = true;
- mmu_notifier_invalidate_range_start(mm,
- mmu_start,
- migrate->end);
+
+ mmu_notifier_range_init(&range,
+ migrate->vma->vm_mm,
+ addr, migrate->end);
+ mmu_notifier_invalidate_range_start(&range);
}
migrate_vma_insert_page(migrate, addr, newpage,
&migrate->src[i],
* did already call it.
*/
if (notified)
- mmu_notifier_invalidate_range_only_end(mm, mmu_start,
- migrate->end);
+ mmu_notifier_invalidate_range_only_end(&range);
}
/*
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