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Gmane
From: Johannes Weiner <jweiner <at> redhat.com>
Subject: [patch 00/10] memcg naturalization -rc4
Newsgroups: gmane.linux.kernel
Date: Thursday 29th September 2011 21:00:54 UTC (over 5 years ago)
Hi,

this is the fourth revision of the memory cgroup naturalization
series.

The changes from v3 have mostly been documentation, changelog, and
naming fixes based on review feedback:

    o drop conversion of no longer existing zone-wide unevictable
      page rescue scanner
    o fix return value of mem_cgroup_hierarchical_reclaim() in
      limit-shrinking mode (Michal)
    o rename @remember to @reclaim in mem_cgroup_iter()
    o convert vm_swappiness to global_reclaim() in the
      correct patch (Michal)
    o rename
      struct mem_cgroup_iter_state -> struct mem_cgroup_reclaim_iter
      and
      struct mem_cgroup_iter -> struct mem_cgroup_reclaim_cookie
      (Michal)
    o added/amended comments and changelogs based on feedback (Michal,
Kame)

Thanks for the review and feedback, guys, it's much appreciated!

The series is based on v3.1-rc3-mmotm-2011-08-24-14-08-11 plus the
following patches included in not-yet-released -mm:

        Revert "memcg: add memory.vmscan_stat"
        memcg: skip scanning active lists based on individual list size
        mm: memcg: close race between charge and putback
        mm: disable user interface to manually rescue unevictable pages

which are attached at the end of this email as monolithic diff.

Also as long as kernel.org is still down, you can find the mmotm
snapshot this series is based on here:

    http://cmpxchg.org/~hannes/v3.1-rc3-mmotm-2011-08-24-14-08-11-broken-out.tar.gz

Or in this git tree:

    http://git.cmpxchg.org/?p=linux-mmotm.git;a=summary

 include/linux/memcontrol.h  |   73 +++--
 include/linux/mm_inline.h   |   21 +-
 include/linux/mmzone.h      |   10 +-
 include/linux/page_cgroup.h |   34 ---
 mm/memcontrol.c             |  691
++++++++++++++++++++-----------------------
 mm/page_alloc.c             |    2 +-
 mm/page_cgroup.c            |   59 +----
 mm/swap.c                   |   24 +-
 mm/vmscan.c                 |  389 +++++++++++++++----------
 9 files changed, 642 insertions(+), 661 deletions(-)

	Hannes

---

diff --git a/Documentation/cgroups/memory.txt
b/Documentation/cgroups/memory.txt
index 6f3c598..06eb6d9 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -380,7 +380,7 @@ will be charged as a new owner of it.
 
 5.2 stat file
 
-5.2.1 memory.stat file includes following statistics
+memory.stat file includes following statistics
 
 # per-memory cgroup local status
 cache		- # of bytes of page cache memory.
@@ -438,89 +438,6 @@ Note:
 	 file_mapped is accounted only when the memory cgroup is owner of page
 	 cache.)
 
-5.2.2 memory.vmscan_stat
-
-memory.vmscan_stat includes statistics information for memory scanning and
-freeing, reclaiming. The statistics shows memory scanning information
since
-memory cgroup creation and can be reset to 0 by writing 0 as
-
- #echo 0 > ../memory.vmscan_stat
-
-This file contains following statistics.
-
-[param]_[file_or_anon]_pages_by_[reason]_[under_heararchy]
-[param]_elapsed_ns_by_[reason]_[under_hierarchy]
-
-For example,
-
-  scanned_file_pages_by_limit indicates the number of scanned
-  file pages at vmscan.
-
-Now, 3 parameters are supported
-
-  scanned - the number of pages scanned by vmscan
-  rotated - the number of pages activated at vmscan
-  freed   - the number of pages freed by vmscan
-
-If "rotated" is high against scanned/freed, the memcg seems busy.
-
-Now, 2 reason are supported
-
-  limit - the memory cgroup's limit
-  system - global memory pressure + softlimit
-           (global memory pressure not under softlimit is not handled now)
-
-When under_hierarchy is added in the tail, the number indicates the
-total memcg scan of its children and itself.
-
-elapsed_ns is a elapsed time in nanosecond. This may include sleep time
-and not indicates CPU usage. So, please take this as just showing
-latency.
-
-Here is an example.
-
-# cat /cgroup/memory/A/memory.vmscan_stat
-scanned_pages_by_limit 9471864
-scanned_anon_pages_by_limit 6640629
-scanned_file_pages_by_limit 2831235
-rotated_pages_by_limit 4243974
-rotated_anon_pages_by_limit 3971968
-rotated_file_pages_by_limit 272006
-freed_pages_by_limit 2318492
-freed_anon_pages_by_limit 962052
-freed_file_pages_by_limit 1356440
-elapsed_ns_by_limit 351386416101
-scanned_pages_by_system 0
-scanned_anon_pages_by_system 0
-scanned_file_pages_by_system 0
-rotated_pages_by_system 0
-rotated_anon_pages_by_system 0
-rotated_file_pages_by_system 0
-freed_pages_by_system 0
-freed_anon_pages_by_system 0
-freed_file_pages_by_system 0
-elapsed_ns_by_system 0
-scanned_pages_by_limit_under_hierarchy 9471864
-scanned_anon_pages_by_limit_under_hierarchy 6640629
-scanned_file_pages_by_limit_under_hierarchy 2831235
-rotated_pages_by_limit_under_hierarchy 4243974
-rotated_anon_pages_by_limit_under_hierarchy 3971968
-rotated_file_pages_by_limit_under_hierarchy 272006
-freed_pages_by_limit_under_hierarchy 2318492
-freed_anon_pages_by_limit_under_hierarchy 962052
-freed_file_pages_by_limit_under_hierarchy 1356440
-elapsed_ns_by_limit_under_hierarchy 351386416101
-scanned_pages_by_system_under_hierarchy 0
-scanned_anon_pages_by_system_under_hierarchy 0
-scanned_file_pages_by_system_under_hierarchy 0
-rotated_pages_by_system_under_hierarchy 0
-rotated_anon_pages_by_system_under_hierarchy 0
-rotated_file_pages_by_system_under_hierarchy 0
-freed_pages_by_system_under_hierarchy 0
-freed_anon_pages_by_system_under_hierarchy 0
-freed_file_pages_by_system_under_hierarchy 0
-elapsed_ns_by_system_under_hierarchy 0
-
 5.3 swappiness
 
 Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups
only.
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index fb1ed1c..b87068a 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -40,16 +40,6 @@ extern unsigned long mem_cgroup_isolate_pages(unsigned
long nr_to_scan,
 					struct mem_cgroup *mem_cont,
 					int active, int file);
 
-struct memcg_scanrecord {
-	struct mem_cgroup *mem; /* scanend memory cgroup */
-	struct mem_cgroup *root; /* scan target hierarchy root */
-	int context;		/* scanning context (see memcontrol.c) */
-	unsigned long nr_scanned[2]; /* the number of scanned pages */
-	unsigned long nr_rotated[2]; /* the number of rotated pages */
-	unsigned long nr_freed[2]; /* the number of freed pages */
-	unsigned long elapsed; /* nsec of time elapsed while scanning */
-};
-
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 /*
  * All "charge" functions with gfp_mask should use GFP_KERNEL or
@@ -116,8 +106,10 @@ extern void mem_cgroup_end_migration(struct mem_cgroup
*memcg,
 /*
  * For memory reclaim.
  */
-int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg);
-int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg);
+int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg,
+				    struct zone *zone);
+int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg,
+				    struct zone *zone);
 int mem_cgroup_select_victim_node(struct mem_cgroup *memcg);
 unsigned long mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg,
 					int nid, int zid, unsigned int lrumask);
@@ -128,15 +120,6 @@ mem_cgroup_get_reclaim_stat_from_page(struct page
*page);
 extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
 					struct task_struct *p);
 
-extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
-						  gfp_t gfp_mask, bool noswap,
-						  struct memcg_scanrecord *rec);
-extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
-						gfp_t gfp_mask, bool noswap,
-						struct zone *zone,
-						struct memcg_scanrecord *rec,
-						unsigned long *nr_scanned);
-
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 extern int do_swap_account;
 #endif
@@ -314,13 +297,13 @@ static inline bool mem_cgroup_disabled(void)
 }
 
 static inline int
-mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
+mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone
*zone)
 {
 	return 1;
 }
 
 static inline int
-mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg)
+mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg, struct zone
*zone)
 {
 	return 1;
 }
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 3808f10..b156e80 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -249,6 +249,12 @@ static inline void lru_cache_add_file(struct page
*page)
 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int
order,
 					gfp_t gfp_mask, nodemask_t *mask);
 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode, int
file);
+extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup
*memcg,
+						  gfp_t gfp_mask, bool noswap);
+extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
+						gfp_t gfp_mask, bool noswap,
+						struct zone *zone,
+						unsigned long *nr_scanned);
 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 extern int vm_swappiness;
 extern int remove_mapping(struct address_space *mapping, struct page
*page);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 54b35b3..b76011a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -205,50 +205,6 @@ struct mem_cgroup_eventfd_list {
 static void mem_cgroup_threshold(struct mem_cgroup *memcg);
 static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
 
-enum {
-	SCAN_BY_LIMIT,
-	SCAN_BY_SYSTEM,
-	NR_SCAN_CONTEXT,
-	SCAN_BY_SHRINK,	/* not recorded now */
-};
-
-enum {
-	SCAN,
-	SCAN_ANON,
-	SCAN_FILE,
-	ROTATE,
-	ROTATE_ANON,
-	ROTATE_FILE,
-	FREED,
-	FREED_ANON,
-	FREED_FILE,
-	ELAPSED,
-	NR_SCANSTATS,
-};
-
-struct scanstat {
-	spinlock_t	lock;
-	unsigned long	stats[NR_SCAN_CONTEXT][NR_SCANSTATS];
-	unsigned long	rootstats[NR_SCAN_CONTEXT][NR_SCANSTATS];
-};
-
-const char *scanstat_string[NR_SCANSTATS] = {
-	"scanned_pages",
-	"scanned_anon_pages",
-	"scanned_file_pages",
-	"rotated_pages",
-	"rotated_anon_pages",
-	"rotated_file_pages",
-	"freed_pages",
-	"freed_anon_pages",
-	"freed_file_pages",
-	"elapsed_ns",
-};
-#define SCANSTAT_WORD_LIMIT	"_by_limit"
-#define SCANSTAT_WORD_SYSTEM	"_by_system"
-#define SCANSTAT_WORD_HIERARCHY	"_under_hierarchy"
-
-
 /*
  * The memory controller data structure. The memory controller controls
both
  * page cache and RSS per cgroup. We would eventually like to provide
@@ -314,8 +270,7 @@ struct mem_cgroup {
 
 	/* For oom notifier event fd */
 	struct list_head oom_notify;
-	/* For recording LRU-scan statistics */
-	struct scanstat scanstat;
+
 	/*
 	 * Should we move charges of a task when a task is moved into this
 	 * mem_cgroup ? And what type of charges should we move ?
@@ -1035,6 +990,16 @@ void mem_cgroup_add_lru_list(struct page *page, enum
lru_list lru)
 		return;
 	pc = lookup_page_cgroup(page);
 	VM_BUG_ON(PageCgroupAcctLRU(pc));
+	/*
+	 * putback:				charge:
+	 * SetPageLRU				SetPageCgroupUsed
+	 * smp_mb				smp_mb
+	 * PageCgroupUsed && add to memcg LRU	PageLRU && add to memcg LRU
+	 *
+	 * Ensure that one of the two sides adds the page to the memcg
+	 * LRU during a race.
+	 */
+	smp_mb();
 	if (!PageCgroupUsed(pc))
 		return;
 	/* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
@@ -1086,7 +1051,16 @@ static void mem_cgroup_lru_add_after_commit(struct
page *page)
 	unsigned long flags;
 	struct zone *zone = page_zone(page);
 	struct page_cgroup *pc = lookup_page_cgroup(page);
-
+	/*
+	 * putback:				charge:
+	 * SetPageLRU				SetPageCgroupUsed
+	 * smp_mb				smp_mb
+	 * PageCgroupUsed && add to memcg LRU	PageLRU && add to memcg LRU
+	 *
+	 * Ensure that one of the two sides adds the page to the memcg
+	 * LRU during a race.
+	 */
+	smp_mb();
 	/* taking care of that the page is added to LRU while we commit it */
 	if (likely(!PageLRU(page)))
 		return;
@@ -1146,15 +1120,19 @@ int task_in_mem_cgroup(struct task_struct *task,
const struct mem_cgroup *memcg)
 	return ret;
 }
 
-static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long
*present_pages)
+int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone
*zone)
 {
-	unsigned long active;
+	unsigned long inactive_ratio;
+	int nid = zone_to_nid(zone);
+	int zid = zone_idx(zone);
 	unsigned long inactive;
+	unsigned long active;
 	unsigned long gb;
-	unsigned long inactive_ratio;
 
-	inactive = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_INACTIVE_ANON));
-	active = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_ACTIVE_ANON));
+	inactive = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
+						BIT(LRU_INACTIVE_ANON));
+	active = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
+					      BIT(LRU_ACTIVE_ANON));
 
 	gb = (inactive + active) >> (30 - PAGE_SHIFT);
 	if (gb)
@@ -1162,39 +1140,20 @@ static int calc_inactive_ratio(struct mem_cgroup
*memcg, unsigned long *present_
 	else
 		inactive_ratio = 1;
 
-	if (present_pages) {
-		present_pages[0] = inactive;
-		present_pages[1] = active;
-	}
-
-	return inactive_ratio;
+	return inactive * inactive_ratio < active;
 }
 
-int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
-{
-	unsigned long active;
-	unsigned long inactive;
-	unsigned long present_pages[2];
-	unsigned long inactive_ratio;
-
-	inactive_ratio = calc_inactive_ratio(memcg, present_pages);
-
-	inactive = present_pages[0];
-	active = present_pages[1];
-
-	if (inactive * inactive_ratio < active)
-		return 1;
-
-	return 0;
-}
-
-int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg)
+int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg, struct zone
*zone)
 {
 	unsigned long active;
 	unsigned long inactive;
+	int zid = zone_idx(zone);
+	int nid = zone_to_nid(zone);
 
-	inactive = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_INACTIVE_FILE));
-	active = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_ACTIVE_FILE));
+	inactive = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
+						BIT(LRU_INACTIVE_FILE));
+	active = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
+					      BIT(LRU_ACTIVE_FILE));
 
 	return (active > inactive);
 }
@@ -1679,44 +1638,6 @@ bool mem_cgroup_reclaimable(struct mem_cgroup
*memcg, bool noswap)
 }
 #endif
 
-static void __mem_cgroup_record_scanstat(unsigned long *stats,
-			   struct memcg_scanrecord *rec)
-{
-
-	stats[SCAN] += rec->nr_scanned[0] + rec->nr_scanned[1];
-	stats[SCAN_ANON] += rec->nr_scanned[0];
-	stats[SCAN_FILE] += rec->nr_scanned[1];
-
-	stats[ROTATE] += rec->nr_rotated[0] + rec->nr_rotated[1];
-	stats[ROTATE_ANON] += rec->nr_rotated[0];
-	stats[ROTATE_FILE] += rec->nr_rotated[1];
-
-	stats[FREED] += rec->nr_freed[0] + rec->nr_freed[1];
-	stats[FREED_ANON] += rec->nr_freed[0];
-	stats[FREED_FILE] += rec->nr_freed[1];
-
-	stats[ELAPSED] += rec->elapsed;
-}
-
-static void mem_cgroup_record_scanstat(struct memcg_scanrecord *rec)
-{
-	struct mem_cgroup *memcg;
-	int context = rec->context;
-
-	if (context >= NR_SCAN_CONTEXT)
-		return;
-
-	memcg = rec->mem;
-	spin_lock(&memcg->scanstat.lock);
-	__mem_cgroup_record_scanstat(memcg->scanstat.stats[context], rec);
-	spin_unlock(&memcg->scanstat.lock);
-
-	memcg = rec->root;
-	spin_lock(&memcg->scanstat.lock);
-	__mem_cgroup_record_scanstat(memcg->scanstat.rootstats[context], rec);
-	spin_unlock(&memcg->scanstat.lock);
-}
-
 /*
  * Scan the hierarchy if needed to reclaim memory. We remember the last
child
  * we reclaimed from, so that we don't end up penalizing one child
extensively
@@ -1741,9 +1662,8 @@ static int mem_cgroup_hierarchical_reclaim(struct
mem_cgroup *root_memcg,
 	bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP;
 	bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK;
 	bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT;
-	struct memcg_scanrecord rec;
 	unsigned long excess;
-	unsigned long scanned;
+	unsigned long nr_scanned;
 
 	excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT;
 
@@ -1751,15 +1671,6 @@ static int mem_cgroup_hierarchical_reclaim(struct
mem_cgroup *root_memcg,
 	if (!check_soft && !shrink && root_memcg->memsw_is_minimum)
 		noswap = true;
 
-	if (shrink)
-		rec.context = SCAN_BY_SHRINK;
-	else if (check_soft)
-		rec.context = SCAN_BY_SYSTEM;
-	else
-		rec.context = SCAN_BY_LIMIT;
-
-	rec.root = root_memcg;
-
 	while (1) {
 		victim = mem_cgroup_select_victim(root_memcg);
 		if (victim == root_memcg) {
@@ -1800,23 +1711,14 @@ static int mem_cgroup_hierarchical_reclaim(struct
mem_cgroup *root_memcg,
 			css_put(&victim->css);
 			continue;
 		}
-		rec.mem = victim;
-		rec.nr_scanned[0] = 0;
-		rec.nr_scanned[1] = 0;
-		rec.nr_rotated[0] = 0;
-		rec.nr_rotated[1] = 0;
-		rec.nr_freed[0] = 0;
-		rec.nr_freed[1] = 0;
-		rec.elapsed = 0;
 		/* we use swappiness of local cgroup */
 		if (check_soft) {
 			ret = mem_cgroup_shrink_node_zone(victim, gfp_mask,
-				noswap, zone, &rec, &scanned);
-			*total_scanned += scanned;
+				noswap, zone, &nr_scanned);
+			*total_scanned += nr_scanned;
 		} else
 			ret = try_to_free_mem_cgroup_pages(victim, gfp_mask,
-						noswap, &rec);
-		mem_cgroup_record_scanstat(&rec);
+						noswap);
 		css_put(&victim->css);
 		/*
 		 * At shrinking usage, we can't check we should stop here or
@@ -3853,18 +3755,14 @@ try_to_free:
 	/* try to free all pages in this cgroup */
 	shrink = 1;
 	while (nr_retries && memcg->res.usage > 0) {
-		struct memcg_scanrecord rec;
 		int progress;
 
 		if (signal_pending(current)) {
 			ret = -EINTR;
 			goto out;
 		}
-		rec.context = SCAN_BY_SHRINK;
-		rec.mem = memcg;
-		rec.root = memcg;
 		progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL,
-						false, &rec);
+						false);
 		if (!progress) {
 			nr_retries--;
 			/* maybe some writeback is necessary */
@@ -4293,8 +4191,6 @@ static int mem_control_stat_show(struct cgroup *cont,
struct cftype *cft,
 	}
 
 #ifdef CONFIG_DEBUG_VM
-	cb->fill(cb, "inactive_ratio", calc_inactive_ratio(mem_cont, NULL));
-
 	{
 		int nid, zid;
 		struct mem_cgroup_per_zone *mz;
@@ -4708,57 +4604,6 @@ static int mem_control_numa_stat_open(struct inode
*unused, struct file *file)
 }
 #endif /* CONFIG_NUMA */
 
-static int mem_cgroup_vmscan_stat_read(struct cgroup *cgrp,
-				struct cftype *cft,
-				struct cgroup_map_cb *cb)
-{
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
-	char string[64];
-	int i;
-
-	for (i = 0; i < NR_SCANSTATS; i++) {
-		strcpy(string, scanstat_string[i]);
-		strcat(string, SCANSTAT_WORD_LIMIT);
-		cb->fill(cb, string, memcg->scanstat.stats[SCAN_BY_LIMIT][i]);
-	}
-
-	for (i = 0; i < NR_SCANSTATS; i++) {
-		strcpy(string, scanstat_string[i]);
-		strcat(string, SCANSTAT_WORD_SYSTEM);
-		cb->fill(cb, string, memcg->scanstat.stats[SCAN_BY_SYSTEM][i]);
-	}
-
-	for (i = 0; i < NR_SCANSTATS; i++) {
-		strcpy(string, scanstat_string[i]);
-		strcat(string, SCANSTAT_WORD_LIMIT);
-		strcat(string, SCANSTAT_WORD_HIERARCHY);
-		cb->fill(cb,
-			string, memcg->scanstat.rootstats[SCAN_BY_LIMIT][i]);
-	}
-	for (i = 0; i < NR_SCANSTATS; i++) {
-		strcpy(string, scanstat_string[i]);
-		strcat(string, SCANSTAT_WORD_SYSTEM);
-		strcat(string, SCANSTAT_WORD_HIERARCHY);
-		cb->fill(cb,
-			string, memcg->scanstat.rootstats[SCAN_BY_SYSTEM][i]);
-	}
-	return 0;
-}
-
-static int mem_cgroup_reset_vmscan_stat(struct cgroup *cgrp,
-				unsigned int event)
-{
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
-
-	spin_lock(&memcg->scanstat.lock);
-	memset(&memcg->scanstat.stats, 0, sizeof(memcg->scanstat.stats));
-	memset(&memcg->scanstat.rootstats,
-		0, sizeof(memcg->scanstat.rootstats));
-	spin_unlock(&memcg->scanstat.lock);
-	return 0;
-}
-
-
 static struct cftype mem_cgroup_files[] = {
 	{
 		.name = "usage_in_bytes",
@@ -4829,11 +4674,6 @@ static struct cftype mem_cgroup_files[] = {
 		.mode = S_IRUGO,
 	},
 #endif
-	{
-		.name = "vmscan_stat",
-		.read_map = mem_cgroup_vmscan_stat_read,
-		.trigger = mem_cgroup_reset_vmscan_stat,
-	},
 };
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
@@ -5097,7 +4937,6 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct
cgroup *cont)
 	atomic_set(&memcg->refcnt, 1);
 	memcg->move_charge_at_immigrate = 0;
 	mutex_init(&memcg->thresholds_lock);
-	spin_lock_init(&memcg->scanstat.lock);
 	return &memcg->css;
 free_out:
 	__mem_cgroup_free(memcg);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 23256e8..71b5616 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -105,7 +105,6 @@ struct scan_control {
 
 	/* Which cgroup do we reclaim from */
 	struct mem_cgroup *mem_cgroup;
-	struct memcg_scanrecord *memcg_record;
 
 	/*
 	 * Nodemask of nodes allowed by the caller. If NULL, all nodes
@@ -1381,8 +1380,6 @@ putback_lru_pages(struct zone *zone, struct
scan_control *sc,
 			int file = is_file_lru(lru);
 			int numpages = hpage_nr_pages(page);
 			reclaim_stat->recent_rotated[file] += numpages;
-			if (!scanning_global_lru(sc))
-				sc->memcg_record->nr_rotated[file] += numpages;
 		}
 		if (!pagevec_add(&pvec, page)) {
 			spin_unlock_irq(&zone->lru_lock);
@@ -1426,10 +1423,6 @@ static noinline_for_stack void
update_isolated_counts(struct zone *zone,
 
 	reclaim_stat->recent_scanned[0] += *nr_anon;
 	reclaim_stat->recent_scanned[1] += *nr_file;
-	if (!scanning_global_lru(sc)) {
-		sc->memcg_record->nr_scanned[0] += *nr_anon;
-		sc->memcg_record->nr_scanned[1] += *nr_file;
-	}
 }
 
 /*
@@ -1551,9 +1544,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct
zone *zone,
 					priority, &nr_dirty, &nr_writeback);
 	}
 
-	if (!scanning_global_lru(sc))
-		sc->memcg_record->nr_freed[file] += nr_reclaimed;
-
 	local_irq_disable();
 	if (current_is_kswapd())
 		__count_vm_events(KSWAPD_STEAL, nr_reclaimed);
@@ -1670,8 +1660,6 @@ static void shrink_active_list(unsigned long
nr_pages, struct zone *zone,
 	}
 
 	reclaim_stat->recent_scanned[file] += nr_taken;
-	if (!scanning_global_lru(sc))
-		sc->memcg_record->nr_scanned[file] += nr_taken;
 
 	__count_zone_vm_events(PGREFILL, zone, pgscanned);
 	if (file)
@@ -1723,8 +1711,6 @@ static void shrink_active_list(unsigned long
nr_pages, struct zone *zone,
 	 * get_scan_ratio.
 	 */
 	reclaim_stat->recent_rotated[file] += nr_rotated;
-	if (!scanning_global_lru(sc))
-		sc->memcg_record->nr_rotated[file] += nr_rotated;
 
 	move_active_pages_to_lru(zone, &l_active,
 						LRU_ACTIVE + file * LRU_FILE);
@@ -1770,7 +1756,7 @@ static int inactive_anon_is_low(struct zone *zone,
struct scan_control *sc)
 	if (scanning_global_lru(sc))
 		low = inactive_anon_is_low_global(zone);
 	else
-		low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup);
+		low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup, zone);
 	return low;
 }
 #else
@@ -1813,7 +1799,7 @@ static int inactive_file_is_low(struct zone *zone,
struct scan_control *sc)
 	if (scanning_global_lru(sc))
 		low = inactive_file_is_low_global(zone);
 	else
-		low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup);
+		low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup, zone);
 	return low;
 }
 
@@ -2313,10 +2299,9 @@ unsigned long try_to_free_pages(struct zonelist
*zonelist, int order,
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 
 unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
-					gfp_t gfp_mask, bool noswap,
-					struct zone *zone,
-					struct memcg_scanrecord *rec,
-					unsigned long *scanned)
+						gfp_t gfp_mask, bool noswap,
+						struct zone *zone,
+						unsigned long *nr_scanned)
 {
 	struct scan_control sc = {
 		.nr_scanned = 0,
@@ -2326,9 +2311,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct
mem_cgroup *mem,
 		.may_swap = !noswap,
 		.order = 0,
 		.mem_cgroup = mem,
-		.memcg_record = rec,
 	};
-	ktime_t start, end;
 
 	sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
 			(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
@@ -2337,7 +2320,6 @@ unsigned long mem_cgroup_shrink_node_zone(struct
mem_cgroup *mem,
 						      sc.may_writepage,
 						      sc.gfp_mask);
 
-	start = ktime_get();
 	/*
 	 * NOTE: Although we can get the priority field, using it
 	 * here is not a good idea, since it limits the pages we can scan.
@@ -2346,25 +2328,19 @@ unsigned long mem_cgroup_shrink_node_zone(struct
mem_cgroup *mem,
 	 * the priority and make it zero.
 	 */
 	shrink_zone(0, zone, &sc);
-	end = ktime_get();
-
-	if (rec)
-		rec->elapsed += ktime_to_ns(ktime_sub(end, start));
-	*scanned = sc.nr_scanned;
 
 	trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
 
+	*nr_scanned = sc.nr_scanned;
 	return sc.nr_reclaimed;
 }
 
 unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
 					   gfp_t gfp_mask,
-					   bool noswap,
-					   struct memcg_scanrecord *rec)
+					   bool noswap)
 {
 	struct zonelist *zonelist;
 	unsigned long nr_reclaimed;
-	ktime_t start, end;
 	int nid;
 	struct scan_control sc = {
 		.may_writepage = !laptop_mode,
@@ -2373,7 +2349,6 @@ unsigned long try_to_free_mem_cgroup_pages(struct
mem_cgroup *mem_cont,
 		.nr_to_reclaim = SWAP_CLUSTER_MAX,
 		.order = 0,
 		.mem_cgroup = mem_cont,
-		.memcg_record = rec,
 		.nodemask = NULL, /* we don't care the placement */
 		.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
 				(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
@@ -2382,7 +2357,6 @@ unsigned long try_to_free_mem_cgroup_pages(struct
mem_cgroup *mem_cont,
 		.gfp_mask = sc.gfp_mask,
 	};
 
-	start = ktime_get();
 	/*
 	 * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't
 	 * take care of from where we get pages. So the node where we start the
@@ -2397,9 +2371,6 @@ unsigned long try_to_free_mem_cgroup_pages(struct
mem_cgroup *mem_cont,
 					    sc.gfp_mask);
 
 	nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
-	end = ktime_get();
-	if (rec)
-		rec->elapsed += ktime_to_ns(ktime_sub(end, start));
 
 	trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
 
@@ -3426,66 +3397,12 @@ void scan_mapping_unevictable_pages(struct
address_space *mapping)
 
 }
 
-/**
- * scan_zone_unevictable_pages - check unevictable list for evictable
pages
- * @zone - zone of which to scan the unevictable list
- *
- * Scan @zone's unevictable LRU lists to check for pages that have become
- * evictable.  Move those that have to @zone's inactive list where they
- * become candidates for reclaim, unless shrink_inactive_zone() decides
- * to reactivate them.  Pages that are still unevictable are rotated
- * back onto @zone's unevictable list.
- */
-#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size
*/
-static void scan_zone_unevictable_pages(struct zone *zone)
+static void warn_scan_unevictable_pages(void)
 {
-	struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list;
-	unsigned long scan;
-	unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE);
-
-	while (nr_to_scan > 0) {
-		unsigned long batch_size = min(nr_to_scan,
-						SCAN_UNEVICTABLE_BATCH_SIZE);
-
-		spin_lock_irq(&zone->lru_lock);
-		for (scan = 0;  scan < batch_size; scan++) {
-			struct page *page = lru_to_page(l_unevictable);
-
-			if (!trylock_page(page))
-				continue;
-
-			prefetchw_prev_lru_page(page, l_unevictable, flags);
-
-			if (likely(PageLRU(page) && PageUnevictable(page)))
-				check_move_unevictable_page(page, zone);
-
-			unlock_page(page);
-		}
-		spin_unlock_irq(&zone->lru_lock);
-
-		nr_to_scan -= batch_size;
-	}
-}
-
-
-/**
- * scan_all_zones_unevictable_pages - scan all unevictable lists for
evictable pages
- *
- * A really big hammer:  scan all zones' unevictable LRU lists to check
for
- * pages that have become evictable.  Move those back to the zones'
- * inactive list where they become candidates for reclaim.
- * This occurs when, e.g., we have unswappable pages on the unevictable
lists,
- * and we add swap to the system.  As such, it runs in the context of a
task
- * that has possibly/probably made some previously unevictable pages
- * evictable.
- */
-static void scan_all_zones_unevictable_pages(void)
-{
-	struct zone *zone;
-
-	for_each_zone(zone) {
-		scan_zone_unevictable_pages(zone);
-	}
+	printk_once(KERN_WARNING
+		    "The scan_unevictable_pages sysctl/node-interface has been "
+		    "disabled for lack of a legitimate use case.  If you have "
+		    "one, please send an email to [email protected]\n");
 }
 
 /*
@@ -3498,11 +3415,8 @@ int scan_unevictable_handler(struct ctl_table
*table, int write,
 			   void __user *buffer,
 			   size_t *length, loff_t *ppos)
 {
+	warn_scan_unevictable_pages();
 	proc_doulongvec_minmax(table, write, buffer, length, ppos);
-
-	if (write && *(unsigned long *)table->data)
-		scan_all_zones_unevictable_pages();
-
 	scan_unevictable_pages = 0;
 	return 0;
 }
@@ -3517,6 +3431,7 @@ static ssize_t read_scan_unevictable_node(struct
sys_device *dev,
 					  struct sysdev_attribute *attr,
 					  char *buf)
 {
+	warn_scan_unevictable_pages();
 	return sprintf(buf, "0\n");	/* always zero; should fit... */
 }
 
@@ -3524,19 +3439,7 @@ static ssize_t write_scan_unevictable_node(struct
sys_device *dev,
 					   struct sysdev_attribute *attr,
 					const char *buf, size_t count)
 {
-	struct zone *node_zones = NODE_DATA(dev->id)->node_zones;
-	struct zone *zone;
-	unsigned long res;
-	unsigned long req = strict_strtoul(buf, 10, &res);
-
-	if (!req)
-		return 1;	/* zero is no-op */
-
-	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
-		if (!populated_zone(zone))
-			continue;
-		scan_zone_unevictable_pages(zone);
-	}
+	warn_scan_unevictable_pages();
 	return 1;
 }
 

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