[Devel] [PATCH RHEL8 COMMIT] mm/list_lru.c: add memcg argument to list_lru_from_kmem()

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-80.1.2.vz8.3.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-80.1.2.vz8.3.4
------>
commit d9be3f6b9b731e56dfed4ce0a34f0960186d73b8
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Thu Apr 2 17:12:39 2020 +0300

    mm/list_lru.c: add memcg argument to list_lru_from_kmem()
    
    This is just refactoring to allow the next patches to have memcg pointer
    in list_lru_from_kmem().
    
    Link: http://lkml.kernel.org/r/153063060664.1818.9541345386733498582.stgit@localhost.localdomain
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    Acked-by: Vladimir Davydov <vdavydov.dev at gmail.com>
    Tested-by: Shakeel Butt <shakeelb at google.com>
    Cc: Al Viro <viro at zeniv.linux.org.uk>
    Cc: Andrey Ryabinin <aryabinin at virtuozzo.com>
    Cc: Chris Wilson <chris at chris-wilson.co.uk>
    Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
    Cc: Guenter Roeck <linux at roeck-us.net>
    Cc: "Huang, Ying" <ying.huang at intel.com>
    Cc: Johannes Weiner <hannes at cmpxchg.org>
    Cc: Josef Bacik <jbacik at fb.com>
    Cc: Li RongQing <lirongqing at baidu.com>
    Cc: Matthew Wilcox <willy at infradead.org>
    Cc: Matthias Kaehlcke <mka at chromium.org>
    Cc: Mel Gorman <mgorman at techsingularity.net>
    Cc: Michal Hocko <mhocko at kernel.org>
    Cc: Minchan Kim <minchan at kernel.org>
    Cc: Philippe Ombredanne <pombredanne at nexb.com>
    Cc: Roman Gushchin <guro at fb.com>
    Cc: Sahitya Tummala <stummala at codeaurora.org>
    Cc: Stephen Rothwell <sfr at canb.auug.org.au>
    Cc: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
    Cc: Thomas Gleixner <tglx at linutronix.de>
    Cc: Waiman Long <longman at redhat.com>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    (cherry picked from commit 44bd4a4759d5a714767aa6be7e806ab54b7fa3a8)
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 mm/list_lru.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/mm/list_lru.c b/mm/list_lru.c
index 077956f8d58f..55a76465f7a2 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -65,18 +65,24 @@ static __always_inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
 }
 
 static inline struct list_lru_one *
-list_lru_from_kmem(struct list_lru_node *nlru, void *ptr)
+list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
+		   struct mem_cgroup **memcg_ptr)
 {
-	struct mem_cgroup *memcg;
+	struct list_lru_one *l = &nlru->lru;
+	struct mem_cgroup *memcg = NULL;
 
 	if (!nlru->memcg_lrus)
-		return &nlru->lru;
+		goto out;
 
 	memcg = mem_cgroup_from_kmem(ptr);
 	if (!memcg)
-		return &nlru->lru;
+		goto out;
 
-	return list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
+	l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
+out:
+	if (memcg_ptr)
+		*memcg_ptr = memcg;
+	return l;
 }
 #else
 static void list_lru_register(struct list_lru *lru)
@@ -99,8 +105,11 @@ list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
 }
 
 static inline struct list_lru_one *
-list_lru_from_kmem(struct list_lru_node *nlru, void *ptr)
+list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
+		   struct mem_cgroup **memcg_ptr)
 {
+	if (memcg_ptr)
+		*memcg_ptr = NULL;
 	return &nlru->lru;
 }
 #endif /* CONFIG_MEMCG_KMEM */
@@ -113,7 +122,7 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item)
 
 	spin_lock(&nlru->lock);
 	if (list_empty(item)) {
-		l = list_lru_from_kmem(nlru, item);
+		l = list_lru_from_kmem(nlru, item, NULL);
 		list_add_tail(item, &l->list);
 		l->nr_items++;
 		nlru->nr_items++;
@@ -133,7 +142,7 @@ bool list_lru_del(struct list_lru *lru, struct list_head *item)
 
 	spin_lock(&nlru->lock);
 	if (!list_empty(item)) {
-		l = list_lru_from_kmem(nlru, item);
+		l = list_lru_from_kmem(nlru, item, NULL);
 		list_del_init(item);
 		l->nr_items--;
 		nlru->nr_items--;