Commit 70dea534 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

mm/swap: convert lru_add to a folio_batch 

When adding folios to the LRU for the first time, the LRU flag will
already be clear, so skip the test-and-clear part of moving from one
LRU to another.

Removes 285 bytes from kernel text, mostly due to removing
__pagevec_lru_add().

Link: https://lkml.kernel.org/r/20220617175020.717127-5-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7d80dd09

mm/swap.c

+26 −49
Original line number Diff line number Diff line
@@ -61,7 +61,7 @@ static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = { 
 */

struct lru_pvecs {

	local_lock_t lock;

	struct pagevec lru_add;

	struct folio_batch lru_add;

	struct pagevec lru_deactivate_file;

	struct pagevec lru_deactivate;

	struct pagevec lru_lazyfree;
@@ -228,14 +228,13 @@ static bool pagevec_add_and_need_flush(struct pagevec *pvec, struct page *page) 


typedef void (*move_fn_t)(struct lruvec *lruvec, struct folio *folio);



static void __pagevec_lru_add_fn(struct folio *folio, struct lruvec *lruvec)

static void lru_add_fn(struct lruvec *lruvec, struct folio *folio)

{

	int was_unevictable = folio_test_clear_unevictable(folio);

	long nr_pages = folio_nr_pages(folio);



	VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);



	folio_set_lru(folio);

	/*

	 * Is an smp_mb__after_atomic() still required here, before

	 * folio_evictable() tests PageMlocked, to rule out the possibility
@@ -269,28 +268,6 @@ static void __pagevec_lru_add_fn(struct folio *folio, struct lruvec *lruvec) 
	trace_mm_lru_insertion(folio);

}



/*

 * Add the passed pages to the LRU, then drop the caller's refcount

 * on them.  Reinitialises the caller's pagevec.

 */

static void __pagevec_lru_add(struct pagevec *pvec)

{

	int i;

	struct lruvec *lruvec = NULL;

	unsigned long flags = 0;



	for (i = 0; i < pagevec_count(pvec); i++) {

		struct folio *folio = page_folio(pvec->pages[i]);



		lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags);

		__pagevec_lru_add_fn(folio, lruvec);

	}

	if (lruvec)

		unlock_page_lruvec_irqrestore(lruvec, flags);

	release_pages(pvec->pages, pvec->nr);

	pagevec_reinit(pvec);

}



static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn)

{

	int i;
@@ -301,7 +278,7 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn) 
		struct folio *folio = fbatch->folios[i];



		/* block memcg migration while the folio moves between lru */

		if (!folio_test_clear_lru(folio))

		if (move_fn != lru_add_fn && !folio_test_clear_lru(folio))

			continue;



		lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags);
@@ -473,26 +450,26 @@ static void folio_activate(struct folio *folio) 


static void __lru_cache_activate_folio(struct folio *folio)

{

	struct pagevec *pvec;

	struct folio_batch *fbatch;

	int i;



	local_lock(&lru_pvecs.lock);

	pvec = this_cpu_ptr(&lru_pvecs.lru_add);

	fbatch = this_cpu_ptr(&lru_pvecs.lru_add);



	/*

	 * Search backwards on the optimistic assumption that the page being

	 * activated has just been added to this pagevec. Note that only

	 * the local pagevec is examined as a !PageLRU page could be in the

	 * Search backwards on the optimistic assumption that the folio being

	 * activated has just been added to this batch. Note that only

	 * the local batch is examined as a !LRU folio could be in the

	 * process of being released, reclaimed, migrated or on a remote

	 * pagevec that is currently being drained. Furthermore, marking

	 * a remote pagevec's page PageActive potentially hits a race where

	 * a page is marked PageActive just after it is added to the inactive

	 * batch that is currently being drained. Furthermore, marking

	 * a remote batch's folio active potentially hits a race where

	 * a folio is marked active just after it is added to the inactive

	 * list causing accounting errors and BUG_ON checks to trigger.

	 */

	for (i = pagevec_count(pvec) - 1; i >= 0; i--) {

		struct page *pagevec_page = pvec->pages[i];

	for (i = folio_batch_count(fbatch) - 1; i >= 0; i--) {

		struct folio *batch_folio = fbatch->folios[i];



		if (pagevec_page == &folio->page) {

		if (batch_folio == folio) {

			folio_set_active(folio);

			break;

		}
@@ -551,16 +528,16 @@ EXPORT_SYMBOL(folio_mark_accessed); 
 */

void folio_add_lru(struct folio *folio)

{

	struct pagevec *pvec;

	struct folio_batch *fbatch;



	VM_BUG_ON_FOLIO(folio_test_active(folio) && folio_test_unevictable(folio), folio);

	VM_BUG_ON_FOLIO(folio_test_active(folio) &&

			folio_test_unevictable(folio), folio);

	VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);



	folio_get(folio);

	local_lock(&lru_pvecs.lock);

	pvec = this_cpu_ptr(&lru_pvecs.lru_add);

	if (pagevec_add_and_need_flush(pvec, &folio->page))

		__pagevec_lru_add(pvec);

	fbatch = this_cpu_ptr(&lru_pvecs.lru_add);

	folio_batch_add_and_move(fbatch, folio, lru_add_fn);

	local_unlock(&lru_pvecs.lock);

}

EXPORT_SYMBOL(folio_add_lru);
@@ -691,11 +668,11 @@ static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec) 
 */

void lru_add_drain_cpu(int cpu)

{

	struct folio_batch *fbatch;

	struct pagevec *pvec = &per_cpu(lru_pvecs.lru_add, cpu);

	struct folio_batch *fbatch = &per_cpu(lru_pvecs.lru_add, cpu);

	struct pagevec *pvec;



	if (pagevec_count(pvec))

		__pagevec_lru_add(pvec);

	if (folio_batch_count(fbatch))

		folio_batch_move_lru(fbatch, lru_add_fn);



	fbatch = &per_cpu(lru_rotate.fbatch, cpu);

	/* Disabling interrupts below acts as a compiler barrier. */
@@ -920,7 +897,7 @@ static inline void __lru_add_drain_all(bool force_all_cpus) 
	for_each_online_cpu(cpu) {

		struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);



		if (pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||

		if (folio_batch_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||

		    data_race(folio_batch_count(&per_cpu(lru_rotate.fbatch, cpu))) ||

		    pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) ||

		    pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) ||
@@ -1084,8 +1061,8 @@ EXPORT_SYMBOL(release_pages); 
 * OK from a correctness point of view but is inefficient - those pages may be

 * cache-warm and we want to give them back to the page allocator ASAP.

 *

 * So __pagevec_release() will drain those queues here.  __pagevec_lru_add()

 * and __pagevec_lru_add_active() call release_pages() directly to avoid

 * So __pagevec_release() will drain those queues here.

 * folio_batch_move_lru() calls folios_put() directly to avoid

 * mutual recursion.

 */

void __pagevec_release(struct pagevec *pvec)