mm/memcg: Convert mem_cgroup_swapout() to take a folio

This removes an assumption that THPs are the only kind of compound
pages and removes a couple of hidden calls to compound_head.  It
also documents that you can't pass a tail page to mem_cgroup_swapout().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/include/linux/swap.h b/include/linux/swap.h
index de36f14..e7cb7a1 100644 (file)
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -741,7 +741,7 @@ static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
 #endif
 
 #ifdef CONFIG_MEMCG_SWAP
-extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
+void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry);
 extern int __mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
 static inline int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
 {
@@ -761,7 +761,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_p
 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
 extern bool mem_cgroup_swap_full(struct page *page);
 #else
-static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
+static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
 {
 }
 

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8fef072..f7fbd5f 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7116,19 +7116,19 @@ static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
 
 /**
  * mem_cgroup_swapout - transfer a memsw charge to swap
- * @page: page whose memsw charge to transfer
+ * @folio: folio whose memsw charge to transfer
  * @entry: swap entry to move the charge to
  *
- * Transfer the memsw charge of @page to @entry.
+ * Transfer the memsw charge of @folio to @entry.
  */
-void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
+void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
 {
        struct mem_cgroup *memcg, *swap_memcg;
        unsigned int nr_entries;
        unsigned short oldid;
 
-       VM_BUG_ON_PAGE(PageLRU(page), page);
-       VM_BUG_ON_PAGE(page_count(page), page);
+       VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
+       VM_BUG_ON_FOLIO(folio_ref_count(folio), folio);
 
        if (mem_cgroup_disabled())
                return;
@@ -7136,9 +7136,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
        if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
                return;
 
-       memcg = page_memcg(page);
+       memcg = folio_memcg(folio);
 
-       VM_WARN_ON_ONCE_PAGE(!memcg, page);
+       VM_WARN_ON_ONCE_FOLIO(!memcg, folio);
        if (!memcg)
                return;
 
@@ -7148,16 +7148,16 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
         * ancestor for the swap instead and transfer the memory+swap charge.
         */
        swap_memcg = mem_cgroup_id_get_online(memcg);
-       nr_entries = thp_nr_pages(page);
+       nr_entries = folio_nr_pages(folio);
        /* Get references for the tail pages, too */
        if (nr_entries > 1)
                mem_cgroup_id_get_many(swap_memcg, nr_entries - 1);
        oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg),
                                   nr_entries);
-       VM_BUG_ON_PAGE(oldid, page);
+       VM_BUG_ON_FOLIO(oldid, folio);
        mod_memcg_state(swap_memcg, MEMCG_SWAP, nr_entries);
 
-       page->memcg_data = 0;
+       folio->memcg_data = 0;
 
        if (!mem_cgroup_is_root(memcg))
                page_counter_uncharge(&memcg->memory, nr_entries);
@@ -7176,7 +7176,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
         */
        VM_BUG_ON(!irqs_disabled());
        mem_cgroup_charge_statistics(memcg, -nr_entries);
-       memcg_check_events(memcg, page_to_nid(page));
+       memcg_check_events(memcg, folio_nid(folio));
 
        css_put(&memcg->css);
 }

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 3b96f6e..4f54c6d 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1288,7 +1288,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
 
        if (PageSwapCache(page)) {
                swp_entry_t swap = { .val = page_private(page) };
-               mem_cgroup_swapout(page, swap);
+               mem_cgroup_swapout(folio, swap);
                if (reclaimed && !mapping_exiting(mapping))
                        shadow = workingset_eviction(folio, target_memcg);
                __delete_from_swap_cache(page, swap, shadow);