From: Eric Dumazet <edumazet@google.com>
Date: Sat, 31 Mar 2018 12:58:56 -0700
Subject: rhashtable: reorganize struct rhashtable layout
Patch-mainline: v4.17-rc1
Git-commit: e5d672a0780d9e7118caad4c171ec88b8299398d
References: CVE-2018-5391 bsc#1103097

While under frags DDOS I noticed unfortunate false sharing between
@nelems and @params.automatic_shrinking

Move @nelems at the end of struct rhashtable so that first cache line
is shared between all cpus, because almost never dirtied.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Michal Kubecek <mkubecek@suse.cz>

---
 include/linux/rhashtable.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -152,25 +152,25 @@ struct rhashtable_params {
 /**
  * struct rhashtable - Hash table handle
  * @tbl: Bucket table
- * @nelems: Number of elements in table
  * @key_len: Key length for hashfn
- * @p: Configuration parameters
  * @max_elems: Maximum number of elements in table
+ * @p: Configuration parameters
  * @rhlist: True if this is an rhltable
  * @run_work: Deferred worker to expand/shrink asynchronously
  * @mutex: Mutex to protect current/future table swapping
  * @lock: Spin lock to protect walker list
+ * @nelems: Number of elements in table
  */
 struct rhashtable {
 	struct bucket_table __rcu	*tbl;
-	atomic_t			nelems;
 	unsigned int			key_len;
-	struct rhashtable_params	p;
 	unsigned int			max_elems;
+	struct rhashtable_params	p;
 	bool				rhlist;
 	struct work_struct		run_work;
 	struct mutex                    mutex;
 	spinlock_t			lock;
+	atomic_t			nelems;
 };
 
 /**