mm: make per-memcg LRU lists exclusive
Now that all code that operated on global per-zone LRU lists is
converted to operate on per-memory cgroup LRU lists instead, there is no
reason to keep the double-LRU scheme around any longer.
The pc->lru member is removed and page->lru is linked directly to the
per-memory cgroup LRU lists, which removes two pointers from a
descriptor that exists for every page frame in the system.
Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Ying Han <yinghan@google.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6e7f849..972878b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -995,6 +995,27 @@
}
EXPORT_SYMBOL(mem_cgroup_count_vm_event);
+/**
+ * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg
+ * @zone: zone of the wanted lruvec
+ * @mem: memcg of the wanted lruvec
+ *
+ * Returns the lru list vector holding pages for the given @zone and
+ * @mem. This can be the global zone lruvec, if the memory controller
+ * is disabled.
+ */
+struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
+ struct mem_cgroup *memcg)
+{
+ struct mem_cgroup_per_zone *mz;
+
+ if (mem_cgroup_disabled())
+ return &zone->lruvec;
+
+ mz = mem_cgroup_zoneinfo(memcg, zone_to_nid(zone), zone_idx(zone));
+ return &mz->lruvec;
+}
+
/*
* Following LRU functions are allowed to be used without PCG_LOCK.
* Operations are called by routine of global LRU independently from memcg.
@@ -1009,84 +1030,29 @@
* When moving account, the page is not on LRU. It's isolated.
*/
-void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
-{
- struct page_cgroup *pc;
- struct mem_cgroup_per_zone *mz;
-
- if (mem_cgroup_disabled())
- return;
- pc = lookup_page_cgroup(page);
- /* can happen while we handle swapcache. */
- if (!TestClearPageCgroupAcctLRU(pc))
- return;
- VM_BUG_ON(!pc->mem_cgroup);
- /*
- * We don't check PCG_USED bit. It's cleared when the "page" is finally
- * removed from global LRU.
- */
- mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
- /* huge page split is done under lru_lock. so, we have no races. */
- MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page);
- VM_BUG_ON(list_empty(&pc->lru));
- list_del_init(&pc->lru);
-}
-
-void mem_cgroup_del_lru(struct page *page)
-{
- mem_cgroup_del_lru_list(page, page_lru(page));
-}
-
-/*
- * Writeback is about to end against a page which has been marked for immediate
- * reclaim. If it still appears to be reclaimable, move it to the tail of the
- * inactive list.
+/**
+ * mem_cgroup_lru_add_list - account for adding an lru page and return lruvec
+ * @zone: zone of the page
+ * @page: the page
+ * @lru: current lru
+ *
+ * This function accounts for @page being added to @lru, and returns
+ * the lruvec for the given @zone and the memcg @page is charged to.
+ *
+ * The callsite is then responsible for physically linking the page to
+ * the returned lruvec->lists[@lru].
*/
-void mem_cgroup_rotate_reclaimable_page(struct page *page)
+struct lruvec *mem_cgroup_lru_add_list(struct zone *zone, struct page *page,
+ enum lru_list lru)
{
struct mem_cgroup_per_zone *mz;
- struct page_cgroup *pc;
- enum lru_list lru = page_lru(page);
-
- if (mem_cgroup_disabled())
- return;
-
- pc = lookup_page_cgroup(page);
- /* unused page is not rotated. */
- if (!PageCgroupUsed(pc))
- return;
- /* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
- smp_rmb();
- mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
- list_move_tail(&pc->lru, &mz->lruvec.lists[lru]);
-}
-
-void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
-{
- struct mem_cgroup_per_zone *mz;
+ struct mem_cgroup *memcg;
struct page_cgroup *pc;
if (mem_cgroup_disabled())
- return;
+ return &zone->lruvec;
pc = lookup_page_cgroup(page);
- /* unused page is not rotated. */
- if (!PageCgroupUsed(pc))
- return;
- /* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
- smp_rmb();
- mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
- list_move(&pc->lru, &mz->lruvec.lists[lru]);
-}
-
-void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
-{
- struct page_cgroup *pc;
- struct mem_cgroup_per_zone *mz;
-
- if (mem_cgroup_disabled())
- return;
- pc = lookup_page_cgroup(page);
VM_BUG_ON(PageCgroupAcctLRU(pc));
/*
* putback: charge:
@@ -1098,15 +1064,89 @@
* LRU during a race.
*/
smp_mb();
- if (!PageCgroupUsed(pc))
- return;
- /* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
- smp_rmb();
- mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
- /* huge page split is done under lru_lock. so, we have no races. */
+ /*
+ * If the page is uncharged, it may be freed soon, but it
+ * could also be swap cache (readahead, swapoff) that needs to
+ * be reclaimable in the future. root_mem_cgroup will babysit
+ * it for the time being.
+ */
+ if (PageCgroupUsed(pc)) {
+ /* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
+ smp_rmb();
+ memcg = pc->mem_cgroup;
+ SetPageCgroupAcctLRU(pc);
+ } else
+ memcg = root_mem_cgroup;
+ mz = page_cgroup_zoneinfo(memcg, page);
+ /* compound_order() is stabilized through lru_lock */
MEM_CGROUP_ZSTAT(mz, lru) += 1 << compound_order(page);
- SetPageCgroupAcctLRU(pc);
- list_add(&pc->lru, &mz->lruvec.lists[lru]);
+ return &mz->lruvec;
+}
+
+/**
+ * mem_cgroup_lru_del_list - account for removing an lru page
+ * @page: the page
+ * @lru: target lru
+ *
+ * This function accounts for @page being removed from @lru.
+ *
+ * The callsite is then responsible for physically unlinking
+ * @page->lru.
+ */
+void mem_cgroup_lru_del_list(struct page *page, enum lru_list lru)
+{
+ struct mem_cgroup_per_zone *mz;
+ struct mem_cgroup *memcg;
+ struct page_cgroup *pc;
+
+ if (mem_cgroup_disabled())
+ return;
+
+ pc = lookup_page_cgroup(page);
+ /*
+ * root_mem_cgroup babysits uncharged LRU pages, but
+ * PageCgroupUsed is cleared when the page is about to get
+ * freed. PageCgroupAcctLRU remembers whether the
+ * LRU-accounting happened against pc->mem_cgroup or
+ * root_mem_cgroup.
+ */
+ if (TestClearPageCgroupAcctLRU(pc)) {
+ VM_BUG_ON(!pc->mem_cgroup);
+ memcg = pc->mem_cgroup;
+ } else
+ memcg = root_mem_cgroup;
+ mz = page_cgroup_zoneinfo(memcg, page);
+ /* huge page split is done under lru_lock. so, we have no races. */
+ MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page);
+}
+
+void mem_cgroup_lru_del(struct page *page)
+{
+ mem_cgroup_lru_del_list(page, page_lru(page));
+}
+
+/**
+ * mem_cgroup_lru_move_lists - account for moving a page between lrus
+ * @zone: zone of the page
+ * @page: the page
+ * @from: current lru
+ * @to: target lru
+ *
+ * This function accounts for @page being moved between the lrus @from
+ * and @to, and returns the lruvec for the given @zone and the memcg
+ * @page is charged to.
+ *
+ * The callsite is then responsible for physically relinking
+ * @page->lru to the returned lruvec->lists[@to].
+ */
+struct lruvec *mem_cgroup_lru_move_lists(struct zone *zone,
+ struct page *page,
+ enum lru_list from,
+ enum lru_list to)
+{
+ /* XXX: Optimize this, especially for @from == @to */
+ mem_cgroup_lru_del_list(page, from);
+ return mem_cgroup_lru_add_list(zone, page, to);
}
/*
@@ -1117,6 +1157,7 @@
*/
static void mem_cgroup_lru_del_before_commit(struct page *page)
{
+ enum lru_list lru;
unsigned long flags;
struct zone *zone = page_zone(page);
struct page_cgroup *pc = lookup_page_cgroup(page);
@@ -1133,17 +1174,28 @@
return;
spin_lock_irqsave(&zone->lru_lock, flags);
+ lru = page_lru(page);
/*
- * Forget old LRU when this page_cgroup is *not* used. This Used bit
- * is guarded by lock_page() because the page is SwapCache.
+ * The uncharged page could still be registered to the LRU of
+ * the stale pc->mem_cgroup.
+ *
+ * As pc->mem_cgroup is about to get overwritten, the old LRU
+ * accounting needs to be taken care of. Let root_mem_cgroup
+ * babysit the page until the new memcg is responsible for it.
+ *
+ * The PCG_USED bit is guarded by lock_page() as the page is
+ * swapcache/pagecache.
*/
- if (!PageCgroupUsed(pc))
- mem_cgroup_del_lru_list(page, page_lru(page));
+ if (PageLRU(page) && PageCgroupAcctLRU(pc) && !PageCgroupUsed(pc)) {
+ del_page_from_lru_list(zone, page, lru);
+ add_page_to_lru_list(zone, page, lru);
+ }
spin_unlock_irqrestore(&zone->lru_lock, flags);
}
static void mem_cgroup_lru_add_after_commit(struct page *page)
{
+ enum lru_list lru;
unsigned long flags;
struct zone *zone = page_zone(page);
struct page_cgroup *pc = lookup_page_cgroup(page);
@@ -1161,22 +1213,22 @@
if (likely(!PageLRU(page)))
return;
spin_lock_irqsave(&zone->lru_lock, flags);
- /* link when the page is linked to LRU but page_cgroup isn't */
- if (PageLRU(page) && !PageCgroupAcctLRU(pc))
- mem_cgroup_add_lru_list(page, page_lru(page));
+ lru = page_lru(page);
+ /*
+ * If the page is not on the LRU, someone will soon put it
+ * there. If it is, and also already accounted for on the
+ * memcg-side, it must be on the right lruvec as setting
+ * pc->mem_cgroup and PageCgroupUsed is properly ordered.
+ * Otherwise, root_mem_cgroup has been babysitting the page
+ * during the charge. Move it to the new memcg now.
+ */
+ if (PageLRU(page) && !PageCgroupAcctLRU(pc)) {
+ del_page_from_lru_list(zone, page, lru);
+ add_page_to_lru_list(zone, page, lru);
+ }
spin_unlock_irqrestore(&zone->lru_lock, flags);
}
-
-void mem_cgroup_move_lists(struct page *page,
- enum lru_list from, enum lru_list to)
-{
- if (mem_cgroup_disabled())
- return;
- mem_cgroup_del_lru_list(page, from);
- mem_cgroup_add_lru_list(page, to);
-}
-
/*
* Checks whether given mem is same or in the root_mem_cgroup's
* hierarchy subtree
@@ -1282,68 +1334,6 @@
return &mz->reclaim_stat;
}
-unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
- struct list_head *dst,
- unsigned long *scanned, int order,
- isolate_mode_t mode,
- struct zone *z,
- struct mem_cgroup *mem_cont,
- int active, int file)
-{
- unsigned long nr_taken = 0;
- struct page *page;
- unsigned long scan;
- LIST_HEAD(pc_list);
- struct list_head *src;
- struct page_cgroup *pc, *tmp;
- int nid = zone_to_nid(z);
- int zid = zone_idx(z);
- struct mem_cgroup_per_zone *mz;
- int lru = LRU_FILE * file + active;
- int ret;
-
- BUG_ON(!mem_cont);
- mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
- src = &mz->lruvec.lists[lru];
-
- scan = 0;
- list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
- if (scan >= nr_to_scan)
- break;
-
- if (unlikely(!PageCgroupUsed(pc)))
- continue;
-
- page = lookup_cgroup_page(pc);
-
- if (unlikely(!PageLRU(page)))
- continue;
-
- scan++;
- ret = __isolate_lru_page(page, mode, file);
- switch (ret) {
- case 0:
- list_move(&page->lru, dst);
- mem_cgroup_del_lru(page);
- nr_taken += hpage_nr_pages(page);
- break;
- case -EBUSY:
- /* we don't affect global LRU but rotate in our LRU */
- mem_cgroup_rotate_lru_list(page, page_lru(page));
- break;
- default:
- break;
- }
- }
-
- *scanned = scan;
-
- trace_mm_vmscan_memcg_isolate(0, nr_to_scan, scan, nr_taken,
- 0, 0, 0, mode);
-
- return nr_taken;
-}
-
#define mem_cgroup_from_res_counter(counter, member) \
container_of(counter, struct mem_cgroup, member)
@@ -3726,11 +3716,11 @@
static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
int node, int zid, enum lru_list lru)
{
- struct zone *zone;
struct mem_cgroup_per_zone *mz;
- struct page_cgroup *pc, *busy;
unsigned long flags, loop;
struct list_head *list;
+ struct page *busy;
+ struct zone *zone;
int ret = 0;
zone = &NODE_DATA(node)->node_zones[zid];
@@ -3742,6 +3732,7 @@
loop += 256;
busy = NULL;
while (loop--) {
+ struct page_cgroup *pc;
struct page *page;
ret = 0;
@@ -3750,16 +3741,16 @@
spin_unlock_irqrestore(&zone->lru_lock, flags);
break;
}
- pc = list_entry(list->prev, struct page_cgroup, lru);
- if (busy == pc) {
- list_move(&pc->lru, list);
+ page = list_entry(list->prev, struct page, lru);
+ if (busy == page) {
+ list_move(&page->lru, list);
busy = NULL;
spin_unlock_irqrestore(&zone->lru_lock, flags);
continue;
}
spin_unlock_irqrestore(&zone->lru_lock, flags);
- page = lookup_cgroup_page(pc);
+ pc = lookup_page_cgroup(page);
ret = mem_cgroup_move_parent(page, pc, memcg, GFP_KERNEL);
if (ret == -ENOMEM)
@@ -3767,7 +3758,7 @@
if (ret == -EBUSY || ret == -EINVAL) {
/* found lock contention or "pc" is obsolete. */
- busy = pc;
+ busy = page;
cond_resched();
} else
busy = NULL;