![[PukiWiki]](image/pukiwiki.png "[PukiWiki]")
*参照元 [#g507626a] #backlinks *説明 [#f7dde913] -パス: [[linux-4.4.1/mm/migrate.c]] -FIXME: これは何？ --説明 **引数 [#ybcb34f3] -struct address_space *mapping -- --[[linux-4.4.1/address_space]] -struct page *newpage -- --[[linux-4.4.1/page]] -struct page *page -- --[[linux-4.4.1/page]] -struct buffer_head *head -- --[[linux-4.4.1/buffer_head]] -enum migrate_mode mode -- --[[linux-4.4.1/migrate_mode]] -int extra_count -- **返り値 [#i762c90b] -int -- **参考 [#l6b54a9f] *実装 [#r5a5690e] /* * Replace the page in the mapping. * * The number of remaining references must be: * 1 for anonymous pages without a mapping * 2 for pages with a mapping * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. */ int migrate_page_move_mapping(struct address_space *mapping, struct page *newpage, struct page *page, struct buffer_head *head, enum migrate_mode mode, int extra_count) { struct zone *oldzone, *newzone; int dirty; int expected_count = 1 + extra_count; void **pslot; - --[[linux-4.4.1/zone]] if (!mapping) { /* Anonymous page without mapping */ if (page_count(page) != expected_count) return -EAGAIN; - --[[linux-4.4.1/page_count()]] /* No turning back from here */ set_page_memcg(newpage, page_memcg(page)); newpage->index = page->index; newpage->mapping = page->mapping; if (PageSwapBacked(page)) SetPageSwapBacked(newpage); return MIGRATEPAGE_SUCCESS; } - --[[linux-4.4.1/set_page_memcg()]] --[[linux-4.4.1/page_memcg()]] --[[linux-4.4.1/PageSwapBacked()]] --[[linux-4.4.1/SetPageSwapBacked()]] oldzone = page_zone(page); newzone = page_zone(newpage); - --[[linux-4.4.1/page_zone()]] spin_lock_irq(&mapping->tree_lock); - --[[linux-4.4.1/spin_lock_irq()]] pslot = radix_tree_lookup_slot(&mapping->page_tree, page_index(page)); - --[[linux-4.4.1/radix_tree_lookup_slot()]] --[[linux-4.4.1/page_index()]] expected_count += 1 + page_has_private(page); if (page_count(page) != expected_count || radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { spin_unlock_irq(&mapping->tree_lock); return -EAGAIN; } - --[[linux-4.4.1/page_has_private()]] --[[linux-4.4.1/page_count()]] --[[linux-4.4.1/radix_tree_deref_slot_protected()]] --[[linux-4.4.1/spin_unlock_irq()]] if (!page_freeze_refs(page, expected_count)) { spin_unlock_irq(&mapping->tree_lock); return -EAGAIN; } - --[[linux-4.4.1/page_freeze_refs()]] --[[linux-4.4.1/spin_unlock_irq()]] /* * 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_unfreeze_refs(page, expected_count); spin_unlock_irq(&mapping->tree_lock); return -EAGAIN; } - --[[linux-4.4.1/buffer_migrate_lock_buffers()]] --[[linux-4.4.1/page_unfreeze_refs()]] --[[linux-4.4.1/spin_unlock_irq()]] /* * Now we know that no one else is looking at the page: * no turning back from here. */ set_page_memcg(newpage, page_memcg(page)); newpage->index = page->index; newpage->mapping = page->mapping; if (PageSwapBacked(page)) SetPageSwapBacked(newpage); - --[[linux-4.4.1/set_page_memcg()]] --[[linux-4.4.1/page_memcg()]] --[[linux-4.4.1/PageSwapBacked()]] --[[linux-4.4.1/SetPageSwapBacked()]] get_page(newpage); /* add cache reference */ if (PageSwapCache(page)) { SetPageSwapCache(newpage); set_page_private(newpage, page_private(page)); } - --[[linux-4.4.1/get_page()]] --[[linux-4.4.1/PageSwapCache()]] --[[linux-4.4.1/SetPageSwapCache()]] --[[linux-4.4.1/set_page_private()]] --[[linux-4.4.1/page_private()]] /* Move dirty while page refs frozen and newpage not yet exposed */ dirty = PageDirty(page); if (dirty) { ClearPageDirty(page); SetPageDirty(newpage); } - --[[linux-4.4.1/PageDirty()]] --[[linux-4.4.1/ClearPageDirty()]] --[[linux-4.4.1/SetPageDirty()]] radix_tree_replace_slot(pslot, newpage); - --[[linux-4.4.1/radix_tree_replace_slot()]] /* * Drop cache reference from old page by unfreezing * to one less reference. * We know this isn't the last reference. */ page_unfreeze_refs(page, expected_count - 1); - --[[linux-4.4.1/page_unfreeze_refs()]] spin_unlock(&mapping->tree_lock); /* Leave irq disabled to prevent preemption while updating stats */ - --[[linux-4.4.1/spin_unlock()]] /* * If moved to a different zone then also account * the page for that zone. Other VM counters will be * taken care of when we establish references to the * new page and drop references to the old page. * * Note that anonymous pages are accounted for * via NR_FILE_PAGES and NR_ANON_PAGES if they * are mapped to swap space. */ if (newzone != oldzone) { __dec_zone_state(oldzone, NR_FILE_PAGES); __inc_zone_state(newzone, NR_FILE_PAGES); if (PageSwapBacked(page) && !PageSwapCache(page)) { __dec_zone_state(oldzone, NR_SHMEM); __inc_zone_state(newzone, NR_SHMEM); } if (dirty && mapping_cap_account_dirty(mapping)) { __dec_zone_state(oldzone, NR_FILE_DIRTY); __inc_zone_state(newzone, NR_FILE_DIRTY); } } local_irq_enable(); - --[[linux-4.4.1/__dec_zone_state()]] --[[linux-4.4.1/__inc_zone_state()]] --[[linux-4.4.1/PageSwapBacked()]] --[[linux-4.4.1/PageSwapCache()]] --[[linux-4.4.1/mapping_cap_account_dirty()]] return MIGRATEPAGE_SUCCESS; } *コメント [#l0c3c578]
