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From:   "Matthew Wilcox (Oracle)" <willy@infradead.org>
To:     linux-kernel@vger.kernel.org
Cc:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
        Christoph Hellwig <hch@lst.de>
Subject: [PATCH v13 043/137] mm/memcg: Convert mem_cgroup_migrate() to take folios
Date:   Mon, 12 Jul 2021 04:05:27 +0100
Message-Id: <20210712030701.4000097-44-willy@infradead.org>
In-Reply-To: <20210712030701.4000097-1-willy@infradead.org>
References: <20210712030701.4000097-1-willy@infradead.org>
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Convert all callers of mem_cgroup_migrate() to call page_folio() first.
They all look like they're using head pages already, but this proves it.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/memcontrol.h |  4 ++--
 mm/filemap.c               |  4 +++-
 mm/memcontrol.c            | 35 +++++++++++++++++------------------
 mm/migrate.c               |  4 +++-
 mm/shmem.c                 |  5 ++++-
 5 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 11486ef4776e..e1939c3398f7 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -712,7 +712,7 @@ void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry);
 void mem_cgroup_uncharge(struct folio *folio);
 void mem_cgroup_uncharge_list(struct list_head *page_list);
 
-void mem_cgroup_migrate(struct page *oldpage, struct page *newpage);
+void mem_cgroup_migrate(struct folio *old, struct folio *new);
 
 /**
  * mem_cgroup_lruvec - get the lru list vector for a memcg & node
@@ -1209,7 +1209,7 @@ static inline void mem_cgroup_uncharge_list(struct list_head *page_list)
 {
 }
 
-static inline void mem_cgroup_migrate(struct page *old, struct page *new)
+static inline void mem_cgroup_migrate(struct folio *old, struct folio *new)
 {
 }
 
diff --git a/mm/filemap.c b/mm/filemap.c
index b8be62793316..cc21da4157f1 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -817,6 +817,8 @@ EXPORT_SYMBOL(file_write_and_wait_range);
  */
 void replace_page_cache_page(struct page *old, struct page *new)
 {
+	struct folio *fold = page_folio(old);
+	struct folio *fnew = page_folio(new);
 	struct address_space *mapping = old->mapping;
 	void (*freepage)(struct page *) = mapping->a_ops->freepage;
 	pgoff_t offset = old->index;
@@ -831,7 +833,7 @@ void replace_page_cache_page(struct page *old, struct page *new)
 	new->mapping = mapping;
 	new->index = offset;
 
-	mem_cgroup_migrate(old, new);
+	mem_cgroup_migrate(fold, fnew);
 
 	xas_lock_irqsave(&xas, flags);
 	xas_store(&xas, new);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c787a87a54ff..06fc88d75a04 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6941,36 +6941,35 @@ void mem_cgroup_uncharge_list(struct list_head *page_list)
 }
 
 /**
- * mem_cgroup_migrate - charge a page's replacement
- * @oldpage: currently circulating page
- * @newpage: replacement page
+ * mem_cgroup_migrate - Charge a folio's replacement.
+ * @old: Currently circulating folio.
+ * @new: Replacement folio.
  *
- * Charge @newpage as a replacement page for @oldpage. @oldpage will
+ * Charge @new as a replacement folio for @old. @old will
  * be uncharged upon free.
  *
- * Both pages must be locked, @newpage->mapping must be set up.
+ * Both folios must be locked, @new->mapping must be set up.
  */
-void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
+void mem_cgroup_migrate(struct folio *old, struct folio *new)
 {
-	struct folio *newfolio = page_folio(newpage);
 	struct mem_cgroup *memcg;
-	unsigned int nr_pages = folio_nr_pages(newfolio);
+	unsigned int nr_pages = folio_nr_pages(new);
 	unsigned long flags;
 
-	VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage);
-	VM_BUG_ON_FOLIO(!folio_locked(newfolio), newfolio);
-	VM_BUG_ON_FOLIO(PageAnon(oldpage) != folio_anon(newfolio), newfolio);
-	VM_BUG_ON_FOLIO(compound_nr(oldpage) != nr_pages, newfolio);
+	VM_BUG_ON_FOLIO(!folio_locked(old), old);
+	VM_BUG_ON_FOLIO(!folio_locked(new), new);
+	VM_BUG_ON_FOLIO(folio_anon(old) != folio_anon(new), new);
+	VM_BUG_ON_FOLIO(folio_nr_pages(old) != nr_pages, new);
 
 	if (mem_cgroup_disabled())
 		return;
 
-	/* Page cache replacement: new page already charged? */
-	if (folio_memcg(newfolio))
+	/* Page cache replacement: new folio already charged? */
+	if (folio_memcg(new))
 		return;
 
-	memcg = page_memcg(oldpage);
-	VM_WARN_ON_ONCE_PAGE(!memcg, oldpage);
+	memcg = folio_memcg(old);
+	VM_WARN_ON_ONCE_FOLIO(!memcg, old);
 	if (!memcg)
 		return;
 
@@ -6982,11 +6981,11 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
 	}
 
 	css_get(&memcg->css);
-	commit_charge(newfolio, memcg);
+	commit_charge(new, memcg);
 
 	local_irq_save(flags);
 	mem_cgroup_charge_statistics(memcg, nr_pages);
-	memcg_check_events(memcg, page_to_nid(newpage));
+	memcg_check_events(memcg, folio_nid(new));
 	local_irq_restore(flags);
 }
 
diff --git a/mm/migrate.c b/mm/migrate.c
index 01c05d7f9d6a..d8df117dca7e 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -589,6 +589,8 @@ void copy_huge_page(struct page *dst, struct page *src)
  */
 void migrate_page_states(struct page *newpage, struct page *page)
 {
+	struct folio *folio = page_folio(page);
+	struct folio *newfolio = page_folio(newpage);
 	int cpupid;
 
 	if (PageError(page))
@@ -656,7 +658,7 @@ void migrate_page_states(struct page *newpage, struct page *page)
 	copy_page_owner(page, newpage);
 
 	if (!PageHuge(page))
-		mem_cgroup_migrate(page, newpage);
+		mem_cgroup_migrate(folio, newfolio);
 }
 EXPORT_SYMBOL(migrate_page_states);
 
diff --git a/mm/shmem.c b/mm/shmem.c
index 3931fed5c8d8..2fd75b4d4974 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1619,6 +1619,7 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 				struct shmem_inode_info *info, pgoff_t index)
 {
 	struct page *oldpage, *newpage;
+	struct folio *old, *new;
 	struct address_space *swap_mapping;
 	swp_entry_t entry;
 	pgoff_t swap_index;
@@ -1655,7 +1656,9 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 	xa_lock_irq(&swap_mapping->i_pages);
 	error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage);
 	if (!error) {
-		mem_cgroup_migrate(oldpage, newpage);
+		old = page_folio(oldpage);
+		new = page_folio(newpage);
+		mem_cgroup_migrate(old, new);
 		__inc_lruvec_page_state(newpage, NR_FILE_PAGES);
 		__dec_lruvec_page_state(oldpage, NR_FILE_PAGES);
 	}
-- 
2.30.2