[Devel] [PATCH RHEL7 COMMIT] ms/mm/memcontrol.c: export mem_cgroup_is_root()

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-862.11.6.vz7.71.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-862.11.6.vz7.71.8
------>
commit f9280a04dcf10fcc0405d4f8da73f18519f925f0
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Wed Sep 5 12:37:13 2018 +0300

    ms/mm/memcontrol.c: export mem_cgroup_is_root()
    
    ms commit dfd2f10ccfd7
    
    This will be used in next patch.
    
    Link: http://lkml.kernel.org/r/153063064347.1818.1987011484100392706.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>
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    =====================
    Patchset description:
    
    Port "Improve shrink_slab() scalability" patchset
    
    https://jira.sw.ru/browse/PSBM-88027
    
    This is backport of the patchset improving the performance
    of overcommited containers with many memcgs and mounts.
    The original set is in Linus' tree, and came into 4.19-rc1.
    
    Kirill Tkhai (12):
          mm: assign id to every memcg-aware shrinker
          mm/memcontrol.c: move up for_each_mem_cgroup{, _tree} defines
          mm, memcg: assign memcg-aware shrinkers bitmap to memcg
          fs: propagate shrinker::id to list_lru
          mm/list_lru.c: add memcg argument to list_lru_from_kmem()
          mm/list_lru: pass dst_memcg argument to memcg_drain_list_lru_node()
          mm/list_lru.c: pass lru argument to memcg_drain_list_lru_node()
          mm/list_lru.c: set bit in memcg shrinker bitmap on first list_lru item appearance
          mm/memcontrol.c: export mem_cgroup_is_root()
          mm/vmscan.c: iterate only over charged shrinkers during memcg shrink_slab()
          mm: add SHRINK_EMPTY shrinker methods return value
          mm/vmscan.c: clear shrinker bit if there are no objects related to memcg
    
    Vladimir Davydov (1):
          mm/vmscan.c: generalize shrink_slab() calls in shrink_node()
---
 include/linux/memcontrol.h | 12 ++++++++++++
 mm/memcontrol.c            |  7 +------
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 6270653cfb91..05078fe37034 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -488,6 +488,8 @@ static inline void sock_release_memcg(struct sock *sk)
 }
 #endif /* CONFIG_INET && CONFIG_MEMCG_KMEM */
 
+extern struct mem_cgroup *root_mem_cgroup;
+
 #ifdef CONFIG_MEMCG_KMEM
 extern struct static_key memcg_kmem_enabled_key;
 
@@ -495,6 +497,11 @@ extern int memcg_nr_cache_ids;
 extern void memcg_get_cache_ids(void);
 extern void memcg_put_cache_ids(void);
 
+static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
+{
+	return (memcg == root_mem_cgroup);
+}
+
 static inline void memcg_stop_kmem_account(void)
 {
 	current->memcg_kmem_skip_account++;
@@ -639,6 +646,11 @@ extern void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
 #define for_each_memcg_cache_index(_idx)	\
 	for (; NULL; )
 
+static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
+{
+	return true;
+}
+
 static inline bool memcg_kmem_enabled(void)
 {
 	return false;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 19d7d6553f59..3eaa16032d54 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -70,7 +70,7 @@ struct cgroup_subsys mem_cgroup_subsys __read_mostly;
 EXPORT_SYMBOL(mem_cgroup_subsys);
 
 #define MEM_CGROUP_RECLAIM_RETRIES	5
-static struct mem_cgroup *root_mem_cgroup __read_mostly;
+struct mem_cgroup *root_mem_cgroup __read_mostly;
 
 #ifdef CONFIG_MEMCG_SWAP
 /* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
@@ -566,11 +566,6 @@ struct vmpressure *css_to_vmpressure(struct cgroup_subsys_state *css)
 	return &mem_cgroup_from_css(css)->vmpressure;
 }
 
-static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
-{
-	return (memcg == root_mem_cgroup);
-}
-
 /* Writing them here to avoid exposing memcg's inner layout */
 #if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)