linux-kernel - [PATCH 16/18] mm: use a folio in zap_pte

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Date:   Fri, 3 Nov 2023 22:01:17 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        Matthew Wilcox <willy@...radead.org>,
        David Hildenbrand <david@...hat.com>,
        <linux-s390@...r.kernel.org>,
        Kefeng Wang <wangkefeng.wang@...wei.com>
Subject: [PATCH 16/18] mm: use a folio in zap_pte_range()

Make should_zap_page() to take a folio and use a folio in
zap_pte_range(), which save several compound_head() calls.

Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 mm/memory.c | 43 ++++++++++++++++++++++++-------------------
 1 file changed, 24 insertions(+), 19 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index fcc04dce8e8a..9b4334de9bf0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1358,19 +1358,19 @@ static inline bool should_zap_cows(struct zap_details *details)
 	return details->even_cows;
 }
 
-/* Decides whether we should zap this page with the page pointer specified */
-static inline bool should_zap_page(struct zap_details *details, struct page *page)
+/* Decides whether we should zap this folio with the folio pointer specified */
+static inline bool should_zap_page(struct zap_details *details, struct folio *folio)
 {
-	/* If we can make a decision without *page.. */
+	/* If we can make a decision without *folio.. */
 	if (should_zap_cows(details))
 		return true;
 
-	/* E.g. the caller passes NULL for the case of a zero page */
-	if (!page)
+	/* E.g. the caller passes NULL for the case of a zero folio */
+	if (!folio)
 		return true;
 
-	/* Otherwise we should only zap non-anon pages */
-	return !PageAnon(page);
+	/* Otherwise we should only zap non-anon folios */
+	return !folio_test_anon(folio);
 }
 
 static inline bool zap_drop_file_uffd_wp(struct zap_details *details)
@@ -1423,6 +1423,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 	arch_enter_lazy_mmu_mode();
 	do {
 		pte_t ptent = ptep_get(pte);
+		struct folio *folio = NULL;
 		struct page *page;
 
 		if (pte_none(ptent))
@@ -1435,7 +1436,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			unsigned int delay_rmap;
 
 			page = vm_normal_page(vma, addr, ptent);
-			if (unlikely(!should_zap_page(details, page)))
+			if (page)
+				folio = page_folio(page);
+
+			if (unlikely(!should_zap_page(details, folio)))
 				continue;
 			ptent = ptep_get_and_clear_full(mm, addr, pte,
 							tlb->fullmm);
@@ -1449,18 +1453,18 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			}
 
 			delay_rmap = 0;
-			if (!PageAnon(page)) {
+			if (!folio_test_anon(folio)) {
 				if (pte_dirty(ptent)) {
-					set_page_dirty(page);
+					folio_set_dirty(folio);
 					if (tlb_delay_rmap(tlb)) {
 						delay_rmap = 1;
 						force_flush = 1;
 					}
 				}
 				if (pte_young(ptent) && likely(vma_has_recency(vma)))
-					mark_page_accessed(page);
+					folio_mark_accessed(folio);
 			}
-			rss[mm_counter(page)]--;
+			rss[mm_counter_folio(folio)]--;
 			if (!delay_rmap) {
 				page_remove_rmap(page, vma, false);
 				if (unlikely(page_mapcount(page) < 0))
@@ -1477,9 +1481,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 		entry = pte_to_swp_entry(ptent);
 		if (is_device_private_entry(entry) ||
 		    is_device_exclusive_entry(entry)) {
-			page = pfn_swap_entry_to_page(entry);
-			if (unlikely(!should_zap_page(details, page)))
+			folio = pfn_swap_entry_to_folio(entry);
+			if (unlikely(!should_zap_page(details, folio)))
 				continue;
+
 			/*
 			 * Both device private/exclusive mappings should only
 			 * work with anonymous page so far, so we don't need to
@@ -1487,10 +1492,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			 * see zap_install_uffd_wp_if_needed().
 			 */
 			WARN_ON_ONCE(!vma_is_anonymous(vma));
-			rss[mm_counter(page)]--;
+			rss[mm_counter_folio(folio)]--;
 			if (is_device_private_entry(entry))
 				page_remove_rmap(page, vma, false);
-			put_page(page);
+			folio_put(folio);
 		} else if (!non_swap_entry(entry)) {
 			/* Genuine swap entry, hence a private anon page */
 			if (!should_zap_cows(details))
@@ -1499,10 +1504,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			if (unlikely(!free_swap_and_cache(entry)))
 				print_bad_pte(vma, addr, ptent, NULL);
 		} else if (is_migration_entry(entry)) {
-			page = pfn_swap_entry_to_page(entry);
-			if (!should_zap_page(details, page))
+			folio = pfn_swap_entry_to_folio(entry);
+			if (!should_zap_page(details, folio))
 				continue;
-			rss[mm_counter(page)]--;
+			rss[mm_counter_folio(folio)]--;
 		} else if (pte_marker_entry_uffd_wp(entry)) {
 			/*
 			 * For anon: always drop the marker; for file: only
-- 
2.27.0