linux-5.15/shrink_active_list() の履歴(No.1)

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• linux-5.15/shrink_active_list() へ行く。
  • 1 (2025-09-11 (木) 19:57:35)

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参照元†

• linux-5.15/shrink_list()
• linux-5.15/shrink_lruvec()

説明†

• パス: linux-5.15/mm/vmscan.c

• FIXME: これは何？
  • 説明

引数†

返り値†

参考†

実装†

/*
 * shrink_active_list() moves pages from the active LRU to the inactive LRU.
 *
 * We move them the other way if the page is referenced by one or more
 * processes.
 *
 * If the pages are mostly unmapped, the processing is fast and it is
 * appropriate to hold lru_lock across the whole operation.  But if
 * the pages are mapped, the processing is slow (page_referenced()), so
 * we should drop lru_lock around each page.  It's impossible to balance
 * this, so instead we remove the pages from the LRU while processing them.
 * It is safe to rely on PG_active against the non-LRU pages in here because
 * nobody will play with that bit on a non-LRU page.
 *
 * The downside is that we have to touch page->_refcount against each page.
 * But we had to alter page->flags anyway.
 */
static void shrink_active_list(unsigned long nr_to_scan,
			       struct lruvec *lruvec,
			       struct scan_control *sc,
			       enum lru_list lru)
{
	unsigned long nr_taken;
	unsigned long nr_scanned;
	unsigned long vm_flags;
	LIST_HEAD(l_hold);	/* The pages which were snipped off */
	LIST_HEAD(l_active);
	LIST_HEAD(l_inactive);
	struct page *page;
	unsigned nr_deactivate, nr_activate;
	unsigned nr_rotated = 0;
	int file = is_file_lru(lru);
	struct pglist_data *pgdat = lruvec_pgdat(lruvec);

	lru_add_drain();

	spin_lock_irq(&lruvec->lru_lock);

• • linux-5.15/LIST_HEAD()
  • linux-5.15/page
  • linux-5.15/is_file_lru()
  • linux-5.15/pglist_data
  • linux-5.15/lruvec_pgdat()
  • linux-5.15/lru_add_drain()
  • linux-5.15/spin_lock_irq()

	nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold,
				     &nr_scanned, sc, lru);

	__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, nr_taken);

• • linux-5.15/isolate_lru_pages()
  • linux-5.15/__mod_node_page_state()

	if (!cgroup_reclaim(sc))
		__count_vm_events(PGREFILL, nr_scanned);
	__count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned);

	spin_unlock_irq(&lruvec->lru_lock);

• • linux-5.15/cgroup_reclaim()
  • linux-5.15/__count_vm_events()
  • linux-5.15/lruvec_memcg()
  • linux-5.15/spin_unlock_irq()

	while (!list_empty(&l_hold)) {
		cond_resched();
		page = lru_to_page(&l_hold);
		list_del(&page->lru);

• • linux-5.15/list_empty()
  • linux-5.15/cond_resched()
  • linux-5.15/lru_to_page()
  • linux-5.15/list_del()

		if (unlikely(!page_evictable(page))) {
			putback_lru_page(page);
			continue;
		}

• • linux-5.15/page_evictable()
  • linux-5.15/putback_lru_page()

		if (unlikely(buffer_heads_over_limit)) {
			if (page_has_private(page) && trylock_page(page)) {
				if (page_has_private(page))
					try_to_release_page(page, 0);
				unlock_page(page);
			}
		}

• • linux-5.15/page_has_private()
  • linux-5.15/trylock_page()
  • linux-5.15/try_to_release_page()
  • linux-5.15/unlock_page()

		if (page_referenced(page, 0, sc->target_mem_cgroup,
				    &vm_flags)) {
			/*
			 * Identify referenced, file-backed active pages and
			 * give them one more trip around the active list. So
			 * that executable code get better chances to stay in
			 * memory under moderate memory pressure.  Anon pages
			 * are not likely to be evicted by use-once streaming
			 * IO, plus JVM can create lots of anon VM_EXEC pages,
			 * so we ignore them here.
			 */
			if ((vm_flags & VM_EXEC) && page_is_file_lru(page)) {
				nr_rotated += thp_nr_pages(page);
				list_add(&page->lru, &l_active);
				continue;
			}
		}

• • linux-5.15/page_referenced()
  • linux-5.15/page_is_file_lru()
  • linux-5.15/thp_nr_pages()
  • linux-5.15/list_add()

		ClearPageActive(page);	/* we are de-activating */
		SetPageWorkingset(page);
		list_add(&page->lru, &l_inactive);
	}

• • linux-5.15/ClearPageActive()
  • linux-5.15/SetPageWorkingset()
  • linux-5.15/list_add()

	/*
	 * Move pages back to the lru list.
	 */
	spin_lock_irq(&lruvec->lru_lock);

	nr_activate = move_pages_to_lru(lruvec, &l_active);
	nr_deactivate = move_pages_to_lru(lruvec, &l_inactive);
	/* Keep all free pages in l_active list */
	list_splice(&l_inactive, &l_active);

• • linux-5.15/spin_lock_irq()
  • linux-5.15/move_pages_to_lru()
  • linux-5.15/list_splice()

	__count_vm_events(PGDEACTIVATE, nr_deactivate);
	__count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate);

• • linux-5.15/__count_vm_events()
  • linux-5.15/__count_memcg_events()
  • linux-5.15/lruvec_memcg()

	__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
	spin_unlock_irq(&lruvec->lru_lock);

• • linux-5.15/__mod_node_page_state()
  • linux-5.15/spin_unlock_irq()

	mem_cgroup_uncharge_list(&l_active);
	free_unref_page_list(&l_active);
	trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate,
			nr_deactivate, nr_rotated, sc->priority, file);
}

• • linux-5.15/mem_cgroup_uncharge_list()
  • linux-5.15/free_unref_page_list()
  • linux-5.15/trace_mm_vmscan_lru_shrink_active()

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