mm: thp: make deferred split shrinker memcg aware

Currently THP deferred split shrinker is not memcg aware, this may cause
premature OOM with some configuration.  For example the below test would
run into premature OOM easily:

$ cgcreate -g memory:thp
$ echo 4G > /sys/fs/cgroup/memory/thp/memory/limit_in_bytes
$ cgexec -g memory:thp transhuge-stress 4000

transhuge-stress comes from kernel selftest.

It is easy to hit OOM, but there are still a lot THP on the deferred split
queue, memcg direct reclaim can't touch them since the deferred split
shrinker is not memcg aware.

Convert deferred split shrinker memcg aware by introducing per memcg
deferred split queue.  The THP should be on either per node or per memcg
deferred split queue if it belongs to a memcg.  When the page is
immigrated to the other memcg, it will be immigrated to the target memcg's
deferred split queue too.

Reuse the second tail page's deferred_list for per memcg list since the
same THP can't be on multiple deferred split queues.

[yang.shi@linux.alibaba.com: simplify deferred split queue dereference per Kirill Tkhai]
  Link: http://lkml.kernel.org/r/1566496227-84952-5-git-send-email-yang.shi@linux.alibaba.com
Link: http://lkml.kernel.org/r/1565144277-36240-5-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a385a7cb7d9f..2156ef775d04 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5071,6 +5071,11 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
 		memcg->cgwb_frn[i].done =
 			__WB_COMPLETION_INIT(&memcg_cgwb_frn_waitq);
 #endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	spin_lock_init(&memcg->deferred_split_queue.split_queue_lock);
+	INIT_LIST_HEAD(&memcg->deferred_split_queue.split_queue);
+	memcg->deferred_split_queue.split_queue_len = 0;
+#endif
 	idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
 	return memcg;
 fail:
@@ -5449,6 +5454,14 @@ static int mem_cgroup_move_account(struct page *page,
 		__mod_memcg_state(to, NR_WRITEBACK, nr_pages);
 	}
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	if (compound && !list_empty(page_deferred_list(page))) {
+		spin_lock(&from->deferred_split_queue.split_queue_lock);
+		list_del_init(page_deferred_list(page));
+		from->deferred_split_queue.split_queue_len--;
+		spin_unlock(&from->deferred_split_queue.split_queue_lock);
+	}
+#endif
 	/*
 	 * It is safe to change page->mem_cgroup here because the page
 	 * is referenced, charged, and isolated - we can't race with
@@ -5457,6 +5470,17 @@ static int mem_cgroup_move_account(struct page *page,
 
 	/* caller should have done css_get */
 	page->mem_cgroup = to;
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	if (compound && list_empty(page_deferred_list(page))) {
+		spin_lock(&to->deferred_split_queue.split_queue_lock);
+		list_add_tail(page_deferred_list(page),
+			      &to->deferred_split_queue.split_queue);
+		to->deferred_split_queue.split_queue_len++;
+		spin_unlock(&to->deferred_split_queue.split_queue_lock);
+	}
+#endif
+
 	spin_unlock_irqrestore(&from->move_lock, flags);
 
 	ret = 0;