[Devel] [PATCH RHEL7 COMMIT] ms/mm: assign id to every memcg-aware shrinker

Konstantin Khorenko khorenko at virtuozzo.com
Wed Sep 5 12:37:09 MSK 2018


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 97b77b03f78043cd7fd95f36757c9046db9f50c3
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Wed Sep 5 12:37:08 2018 +0300

    ms/mm: assign id to every memcg-aware shrinker
    
    ms commit b4c2b231c3ba
    
    Introduce shrinker::id number, which is used to enumerate memcg-aware
    shrinkers.  The number start from 0, and the code tries to maintain it
    as small as possible.
    
    This will be used to represent a memcg-aware shrinkers in memcg
    shrinkers map.
    
    Since all memcg-aware shrinkers are based on list_lru, which is
    per-memcg in case of !CONFIG_MEMCG_KMEM only, the new functionality will
    be under this config option.
    
    [ktkhai at virtuozzo.com: v9]
     Link: http://lkml.kernel.org/r/153112546435.4097.10607140323811756557.stgit@localhost.localdomain
     Link: http://lkml.kernel.org/r/153063054586.1818.6041047871606697364.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/shrinker.h |  5 +++-
 mm/vmscan.c              | 60 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 5e706a524592..a8bbeaa3c66e 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -53,7 +53,10 @@ struct shrinker {
 				       struct shrink_control *sc);
 	unsigned long (*scan_objects)(struct shrinker *,
 				      struct shrink_control *sc);
-
+#ifdef CONFIG_MEMCG_KMEM
+	/* ID in shrinker_idr */
+	int id;
+#endif
 	int seeks;	/* seeks to recreate an obj */
 	long batch;	/* reclaim batch size, 0 = default */
 	unsigned long flags;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index aefa4bc33062..418154200a76 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -157,6 +157,49 @@ unsigned long vm_total_pages;	/* The total number of pages which the VM controls
 static LIST_HEAD(shrinker_list);
 static DECLARE_RWSEM(shrinker_rwsem);
 
+#ifdef CONFIG_MEMCG_KMEM
+static DEFINE_IDR(shrinker_idr);
+static int shrinker_nr_max;
+
+static int register_memcg_shrinker(struct shrinker *shrinker)
+{
+	int id, ret = -ENOMEM;
+
+	down_write(&shrinker_rwsem);
+	/* This may call shrinker, so it must use down_read_trylock() */
+	id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);
+	if (id < 0)
+		goto unlock;
+
+	if (id >= shrinker_nr_max)
+		shrinker_nr_max = id + 1;
+	shrinker->id = id;
+	ret = 0;
+unlock:
+	up_write(&shrinker_rwsem);
+	return ret;
+}
+
+static void unregister_memcg_shrinker(struct shrinker *shrinker)
+{
+	int id = shrinker->id;
+
+	BUG_ON(id < 0);
+
+	down_write(&shrinker_rwsem);
+	idr_remove(&shrinker_idr, id);
+	up_write(&shrinker_rwsem);
+}
+#else /* CONFIG_MEMCG_KMEM */
+static int register_memcg_shrinker(struct shrinker *shrinker)
+{
+	return 0;
+}
+static void unregister_memcg_shrinker(struct shrinker *shrinker)
+{
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
 #ifdef CONFIG_MEMCG
 static bool global_reclaim(struct scan_control *sc)
 {
@@ -249,10 +292,20 @@ int register_shrinker(struct shrinker *shrinker)
 	if (!shrinker->nr_deferred)
 		return -ENOMEM;
 
+	if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
+		if (register_memcg_shrinker(shrinker))
+			goto free_deferred;
+	}
+
 	down_write(&shrinker_rwsem);
 	list_add_tail(&shrinker->list, &shrinker_list);
 	up_write(&shrinker_rwsem);
 	return 0;
+
+free_deferred:
+	kfree(shrinker->nr_deferred);
+	shrinker->nr_deferred = NULL;
+	return -ENOMEM;
 }
 EXPORT_SYMBOL(register_shrinker);
 
@@ -261,10 +314,17 @@ EXPORT_SYMBOL(register_shrinker);
  */
 void unregister_shrinker(struct shrinker *shrinker)
 {
+	if (!shrinker->nr_deferred)
+		return;
+
+	if (shrinker->flags & SHRINKER_MEMCG_AWARE)
+		unregister_memcg_shrinker(shrinker);
+
 	down_write(&shrinker_rwsem);
 	list_del(&shrinker->list);
 	up_write(&shrinker_rwsem);
 	kfree(shrinker->nr_deferred);
+	shrinker->nr_deferred = NULL;
 }
 EXPORT_SYMBOL(unregister_shrinker);
 


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