mm: memcontrol: delete unused lrucare handling

Swapin faults were the last event to charge pages after they had already
been put on the LRU list.  Now that we charge directly on swapin, the
lrucare portion of the charge code is unused.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-19-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/filemap.c b/mm/filemap.c
index f08b0ca..4559906 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -845,7 +845,7 @@ static int __add_to_page_cache_locked(struct page *page,
 	page->index = offset;
 
 	if (!huge) {
-		error = mem_cgroup_charge(page, current->mm, gfp_mask, false);
+		error = mem_cgroup_charge(page, current->mm, gfp_mask);
 		if (error)
 			goto error;
 	}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e9201a8..6df182a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -593,7 +593,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
 
 	VM_BUG_ON_PAGE(!PageCompound(page), page);
 
-	if (mem_cgroup_charge(page, vma->vm_mm, gfp, false)) {
+	if (mem_cgroup_charge(page, vma->vm_mm, gfp)) {
 		put_page(page);
 		count_vm_event(THP_FAULT_FALLBACK);
 		count_vm_event(THP_FAULT_FALLBACK_CHARGE);
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 32c85b8..f29038c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1059,7 +1059,7 @@ static void collapse_huge_page(struct mm_struct *mm,
 		goto out_nolock;
 	}
 
-	if (unlikely(mem_cgroup_charge(new_page, mm, gfp, false))) {
+	if (unlikely(mem_cgroup_charge(new_page, mm, gfp))) {
 		result = SCAN_CGROUP_CHARGE_FAIL;
 		goto out_nolock;
 	}
@@ -1632,7 +1632,7 @@ static void collapse_file(struct mm_struct *mm,
 		goto out;
 	}
 
-	if (unlikely(mem_cgroup_charge(new_page, mm, gfp, false))) {
+	if (unlikely(mem_cgroup_charge(new_page, mm, gfp))) {
 		result = SCAN_CGROUP_CHARGE_FAIL;
 		goto out;
 	}
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 425a265..316a840 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2655,51 +2655,9 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
 }
 #endif
 
-static void lock_page_lru(struct page *page, int *isolated)
+static void commit_charge(struct page *page, struct mem_cgroup *memcg)
 {
-	pg_data_t *pgdat = page_pgdat(page);
-
-	spin_lock_irq(&pgdat->lru_lock);
-	if (PageLRU(page)) {
-		struct lruvec *lruvec;
-
-		lruvec = mem_cgroup_page_lruvec(page, pgdat);
-		ClearPageLRU(page);
-		del_page_from_lru_list(page, lruvec, page_lru(page));
-		*isolated = 1;
-	} else
-		*isolated = 0;
-}
-
-static void unlock_page_lru(struct page *page, int isolated)
-{
-	pg_data_t *pgdat = page_pgdat(page);
-
-	if (isolated) {
-		struct lruvec *lruvec;
-
-		lruvec = mem_cgroup_page_lruvec(page, pgdat);
-		VM_BUG_ON_PAGE(PageLRU(page), page);
-		SetPageLRU(page);
-		add_page_to_lru_list(page, lruvec, page_lru(page));
-	}
-	spin_unlock_irq(&pgdat->lru_lock);
-}
-
-static void commit_charge(struct page *page, struct mem_cgroup *memcg,
-			  bool lrucare)
-{
-	int isolated;
-
 	VM_BUG_ON_PAGE(page->mem_cgroup, page);
-
-	/*
-	 * In some cases, SwapCache and FUSE(splice_buf->radixtree), the page
-	 * may already be on some other mem_cgroup's LRU.  Take care of it.
-	 */
-	if (lrucare)
-		lock_page_lru(page, &isolated);
-
 	/*
 	 * Nobody should be changing or seriously looking at
 	 * page->mem_cgroup at this point:
@@ -2715,9 +2673,6 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
 	 *   have the page locked
 	 */
 	page->mem_cgroup = memcg;
-
-	if (lrucare)
-		unlock_page_lru(page, isolated);
 }
 
 #ifdef CONFIG_MEMCG_KMEM
@@ -6503,22 +6458,18 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
  * @page: page to charge
  * @mm: mm context of the victim
  * @gfp_mask: reclaim mode
- * @lrucare: page might be on the LRU already
  *
  * Try to charge @page to the memcg that @mm belongs to, reclaiming
  * pages according to @gfp_mask if necessary.
  *
  * Returns 0 on success. Otherwise, an error code is returned.
  */
-int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask,
-		      bool lrucare)
+int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask)
 {
 	unsigned int nr_pages = hpage_nr_pages(page);
 	struct mem_cgroup *memcg = NULL;
 	int ret = 0;
 
-	VM_BUG_ON_PAGE(PageLRU(page) && !lrucare, page);
-
 	if (mem_cgroup_disabled())
 		goto out;
 
@@ -6552,7 +6503,7 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask,
 	if (ret)
 		goto out_put;
 
-	commit_charge(page, memcg, lrucare);
+	commit_charge(page, memcg);
 
 	local_irq_disable();
 	mem_cgroup_charge_statistics(memcg, page, nr_pages);
@@ -6753,7 +6704,7 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
 		page_counter_charge(&memcg->memsw, nr_pages);
 	css_get_many(&memcg->css, nr_pages);
 
-	commit_charge(newpage, memcg, false);
+	commit_charge(newpage, memcg);
 
 	local_irq_save(flags);
 	mem_cgroup_charge_statistics(memcg, newpage, nr_pages);
diff --git a/mm/memory.c b/mm/memory.c
index 9c886e4..d50d8b4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2675,7 +2675,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 		}
 	}
 
-	if (mem_cgroup_charge(new_page, mm, GFP_KERNEL, false))
+	if (mem_cgroup_charge(new_page, mm, GFP_KERNEL))
 		goto oom_free_new;
 	cgroup_throttle_swaprate(new_page, GFP_KERNEL);
 
@@ -3134,7 +3134,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 				/* Tell memcg to use swap ownership records */
 				SetPageSwapCache(page);
 				err = mem_cgroup_charge(page, vma->vm_mm,
-							GFP_KERNEL, false);
+							GFP_KERNEL);
 				ClearPageSwapCache(page);
 				if (err)
 					goto out_page;
@@ -3358,7 +3358,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 	if (!page)
 		goto oom;
 
-	if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL, false))
+	if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL))
 		goto oom_free_page;
 	cgroup_throttle_swaprate(page, GFP_KERNEL);
 
@@ -3854,7 +3854,7 @@ static vm_fault_t do_cow_fault(struct vm_fault *vmf)
 	if (!vmf->cow_page)
 		return VM_FAULT_OOM;
 
-	if (mem_cgroup_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL, false)) {
+	if (mem_cgroup_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL)) {
 		put_page(vmf->cow_page);
 		return VM_FAULT_OOM;
 	}
diff --git a/mm/migrate.c b/mm/migrate.c
index 44cee40..7bfd096 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2786,7 +2786,7 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
 
 	if (unlikely(anon_vma_prepare(vma)))
 		goto abort;
-	if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL, false))
+	if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL))
 		goto abort;
 
 	/*
diff --git a/mm/shmem.c b/mm/shmem.c
index b791161..e83de27 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -624,7 +624,7 @@ static int shmem_add_to_page_cache(struct page *page,
 	page->index = index;
 
 	if (!PageSwapCache(page)) {
-		error = mem_cgroup_charge(page, charge_mm, gfp, false);
+		error = mem_cgroup_charge(page, charge_mm, gfp);
 		if (error) {
 			if (PageTransHuge(page)) {
 				count_vm_event(THP_FILE_FALLBACK);
diff --git a/mm/swap_state.c b/mm/swap_state.c
index f841257..ab04628 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -435,7 +435,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 		goto fail_unlock;
 	}
 
-	if (mem_cgroup_charge(page, NULL, gfp_mask, false)) {
+	if (mem_cgroup_charge(page, NULL, gfp_mask)) {
 		delete_from_swap_cache(page);
 		goto fail_unlock;
 	}
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 2745489..7f51940 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -96,7 +96,7 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
 	__SetPageUptodate(page);
 
 	ret = -ENOMEM;
-	if (mem_cgroup_charge(page, dst_mm, GFP_KERNEL, false))
+	if (mem_cgroup_charge(page, dst_mm, GFP_KERNEL))
 		goto out_release;
 
 	_dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot));