[RFC][PATCH] Add file RSS accounting to the memory resourcecontroller

[Balbir Singh]

Feature: Add file RSS tracking per memory cgroup

From: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>

Testing

1. Feature enabled, built and booted the kernel. Mounted the memory
resource controller and verified the statistics
2. Compiled with CGROUP_MEM_RES_CTLR disabled

We currently don't track file RSS, the RSS we report is actually anon RSS.
All the file mapped pages, come in through the page cache and get accounted
there. This patch adds support for accounting file RSS pages. It should

1. Help improve the metrics reported by the memory resource controller
2. Will form the basis for a future shared memory accounting heuristic
   that has been proposed by Kamezawa.

Unfortunately, we cannot rename the existing "rss" keyword used in memory.stat
to "anon_rss". We however, add "file_rss" data and hope to educate the end
user through documentation.
---

 include/linux/memcontrol.h |    7 +++++++
 include/linux/rmap.h       |    4 ++--
 mm/filemap_xip.c           |    2 +-
 mm/fremap.c                |    2 +-
 mm/memcontrol.c            |   34 +++++++++++++++++++++++++++++++++-
 mm/memory.c                |    8 ++++----
 mm/migrate.c               |    2 +-
 mm/rmap.c                  |   13 ++++++++-----
 8 files changed, 57 insertions(+), 15 deletions(-)


diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 18146c9..c844a13 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -116,6 +116,8 @@ static inline bool mem_cgroup_disabled(void)
 }
 
 extern bool mem_cgroup_oom_called(struct task_struct *task);
+extern void
+mem_cgroup_update_statistics(struct page *page, struct mm_struct *mm, int val);
 
 #else /* CONFIG_CGROUP_MEM_RES_CTLR */
 struct mem_cgroup;
@@ -264,6 +266,11 @@ mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
 {
 }
 
+static inline void
+mem_cgroup_update_statistics(struct page *page, struct mm_struct *mm, int val)
+{
+}
+
 #endif /* CONFIG_CGROUP_MEM_CONT */
 
 #endif /* _LINUX_MEMCONTROL_H */
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index b35bc0e..01b4af1 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -68,8 +68,8 @@ void __anon_vma_link(struct vm_area_struct *);
  */
 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
-void page_add_file_rmap(struct page *);
-void page_remove_rmap(struct page *);
+void page_add_file_rmap(struct page *, struct vm_area_struct *);
+void page_remove_rmap(struct page *, struct vm_area_struct *);
 
 #ifdef CONFIG_DEBUG_VM
 void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address);
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 427dfe3..e8b2b18 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -193,7 +193,7 @@ retry:
 			/* Nuke the page table entry. */
 			flush_cache_page(vma, address, pte_pfn(*pte));
 			pteval = ptep_clear_flush_notify(vma, address, pte);
-			page_remove_rmap(page);
+			page_remove_rmap(page, vma);
 			dec_mm_counter(mm, file_rss);
 			BUG_ON(pte_dirty(pteval));
 			pte_unmap_unlock(pte, ptl);
diff --git a/mm/fremap.c b/mm/fremap.c
index b6ec85a..01ea2da 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -37,7 +37,7 @@ static void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
 		if (page) {
 			if (pte_dirty(pte))
 				set_page_dirty(page);
-			page_remove_rmap(page);
+			page_remove_rmap(page, vma);
 			page_cache_release(page);
 			update_hiwater_rss(mm);
 			dec_mm_counter(mm, file_rss);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e44fb0f..d903b61 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -62,7 +62,8 @@ enum mem_cgroup_stat_index {
 	 * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
 	 */
 	MEM_CGROUP_STAT_CACHE, 	   /* # of pages charged as cache */
-	MEM_CGROUP_STAT_RSS,	   /* # of pages charged as rss */
+	MEM_CGROUP_STAT_RSS,	   /* # of pages charged as anon rss */
+	MEM_CGROUP_STAT_FILE_RSS,  /* # of pages charged as file rss */
 	MEM_CGROUP_STAT_PGPGIN_COUNT,	/* # of pages paged in */
 	MEM_CGROUP_STAT_PGPGOUT_COUNT,	/* # of pages paged out */
 
@@ -321,6 +322,33 @@ static bool mem_cgroup_is_obsolete(struct mem_cgroup *mem)
 	return css_is_removed(&mem->css);
 }
 
+/*
+ * Currently used to update file_rss statistics, but the routine can be
+ * generalized to update other statistics as well.
+ */
+void
+mem_cgroup_update_statistics(struct page *page, struct mm_struct *mm, int val)
+{
+	struct mem_cgroup *mem;
+	struct mem_cgroup_stat *stat;
+	struct mem_cgroup_stat_cpu *cpustat;
+	int cpu = get_cpu();
+
+	if (!page_is_file_cache(page))
+		return;
+
+	if (unlikely(!mm))
+		mm = &init_mm;
+
+	mem = try_get_mem_cgroup_from_mm(mm);
+	if (!mem)
+		return;
+
+	stat = &mem->stat;
+	cpustat = &stat->cpustat[cpu];
+
+	__mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_FILE_RSS, val);
+}
 
 /*
  * Call callback function against all cgroup under hierarchy tree.
@@ -2051,6 +2079,7 @@ static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
 enum {
 	MCS_CACHE,
 	MCS_RSS,
+	MCS_FILE_RSS,
 	MCS_PGPGIN,
 	MCS_PGPGOUT,
 	MCS_INACTIVE_ANON,
@@ -2071,6 +2100,7 @@ struct {
 } memcg_stat_strings[NR_MCS_STAT] = {
 	{"cache", "total_cache"},
 	{"rss", "total_rss"},
+	{"file_rss", "total_file_rss"},
 	{"pgpgin", "total_pgpgin"},
 	{"pgpgout", "total_pgpgout"},
 	{"inactive_anon", "total_inactive_anon"},
@@ -2091,6 +2121,8 @@ static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data)
 	s->stat[MCS_CACHE] += val * PAGE_SIZE;
 	val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_RSS);
 	s->stat[MCS_RSS] += val * PAGE_SIZE;
+	val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_FILE_RSS);
+	s->stat[MCS_FILE_RSS] += val * PAGE_SIZE;
 	val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_PGPGIN_COUNT);
 	s->stat[MCS_PGPGIN] += val;
 	val = mem_cgroup_read_stat(&mem->stat, MEM_CGROUP_STAT_PGPGOUT_COUNT);
diff --git a/mm/memory.c b/mm/memory.c
index a715b19..95a9ded 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -822,7 +822,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 					mark_page_accessed(page);
 				file_rss--;
 			}
-			page_remove_rmap(page);
+			page_remove_rmap(page, vma);
 			if (unlikely(page_mapcount(page) < 0))
 				print_bad_pte(vma, addr, ptent, page);
 			tlb_remove_page(tlb, page);
@@ -1421,7 +1421,7 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
 	/* Ok, finally just insert the thing.. */
 	get_page(page);
 	inc_mm_counter(mm, file_rss);
-	page_add_file_rmap(page);
+	page_add_file_rmap(page, vma);
 	set_pte_at(mm, addr, pte, mk_pte(page, prot));
 
 	retval = 0;
@@ -2080,7 +2080,7 @@ gotten:
 			 * mapcount is visible. So transitively, TLBs to
 			 * old page will be flushed before it can be reused.
 			 */
-			page_remove_rmap(old_page);
+			page_remove_rmap(old_page, vma);
 		}
 
 		/* Free the old page.. */
@@ -2718,7 +2718,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 			page_add_new_anon_rmap(page, vma, address);
 		} else {
 			inc_mm_counter(mm, file_rss);
-			page_add_file_rmap(page);
+			page_add_file_rmap(page, vma);
 			if (flags & FAULT_FLAG_WRITE) {
 				dirty_page = page;
 				get_page(dirty_page);
diff --git a/mm/migrate.c b/mm/migrate.c
index 068655d..098d365 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -131,7 +131,7 @@ static void remove_migration_pte(struct vm_area_struct *vma,
 	if (PageAnon(new))
 		page_add_anon_rmap(new, vma, addr);
 	else
-		page_add_file_rmap(new);
+		page_add_file_rmap(new, vma);
 
 	/* No need to invalidate - it was non-present before */
 	update_mmu_cache(vma, addr, pte);
diff --git a/mm/rmap.c b/mm/rmap.c
index 1652166..3ece45e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -686,10 +686,12 @@ void page_add_new_anon_rmap(struct page *page,
  *
  * The caller needs to hold the pte lock.
  */
-void page_add_file_rmap(struct page *page)
+void page_add_file_rmap(struct page *page, struct vm_area_struct *vma)
 {
-	if (atomic_inc_and_test(&page->_mapcount))
+	if (atomic_inc_and_test(&page->_mapcount)) {
 		__inc_zone_page_state(page, NR_FILE_MAPPED);
+		mem_cgroup_update_statistics(page, vma->vm_mm, 1);
+	}
 }
 
 #ifdef CONFIG_DEBUG_VM
@@ -719,7 +721,7 @@ void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long
  *
  * The caller needs to hold the pte lock.
  */
-void page_remove_rmap(struct page *page)
+void page_remove_rmap(struct page *page, struct vm_area_struct *vma)
 {
 	if (atomic_add_negative(-1, &page->_mapcount)) {
 		/*
@@ -738,6 +740,7 @@ void page_remove_rmap(struct page *page)
 			mem_cgroup_uncharge_page(page);
 		__dec_zone_page_state(page,
 			PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
+		mem_cgroup_update_statistics(page, vma->vm_mm, -1);
 		/*
 		 * It would be tidy to reset the PageAnon mapping here,
 		 * but that might overwrite a racing page_add_anon_rmap
@@ -835,7 +838,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 		dec_mm_counter(mm, file_rss);
 
 
-	page_remove_rmap(page);
+	page_remove_rmap(page, vma);
 	page_cache_release(page);
 
 out_unmap:
@@ -950,7 +953,7 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
 		if (pte_dirty(pteval))
 			set_page_dirty(page);
 
-		page_remove_rmap(page);
+		page_remove_rmap(page, vma);
 		page_cache_release(page);
 		dec_mm_counter(mm, file_rss);
 		(*mapcount)--;

-- 
	Balbir
--
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