diff mbox series

[v3,3/4] mm: shrinker: make shrinker not depend on memcg kmem

Message ID 1560376609-113689-4-git-send-email-yang.shi@linux.alibaba.com (mailing list archive)
State New, archived
Headers show
Series Make deferred split shrinker memcg aware | expand

Commit Message

Yang Shi June 12, 2019, 9:56 p.m. UTC 
Currently shrinker is just allocated and can work when memcg kmem is
enabled.  But, THP deferred split shrinker is not slab shrinker, it
doesn't make too much sense to have such shrinker depend on memcg kmem.
It should be able to reclaim THP even though memcg kmem is disabled.

Introduce a new shrinker flag, SHRINKER_NONSLAB, for non-slab shrinker.
When memcg kmem is disabled, just such shrinkers can be called in
shrinking memcg slab.

Cc: 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>
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
---
 include/linux/shrinker.h |  3 +--
 mm/vmscan.c              | 27 ++++++---------------------
 2 files changed, 7 insertions(+), 23 deletions(-)

Comments

Andrew Morton June 25, 2019, 10:14 p.m. UTC | #1 
On Thu, 13 Jun 2019 05:56:48 +0800 Yang Shi <yang.shi@linux.alibaba.com> wrote:

> Currently shrinker is just allocated and can work when memcg kmem is
> enabled.  But, THP deferred split shrinker is not slab shrinker, it
> doesn't make too much sense to have such shrinker depend on memcg kmem.
> It should be able to reclaim THP even though memcg kmem is disabled.
> 
> Introduce a new shrinker flag, SHRINKER_NONSLAB, for non-slab shrinker.
> When memcg kmem is disabled, just such shrinkers can be called in
> shrinking memcg slab.

This causes a couple of compile errors with an allnoconfig build. 
Please fix that and test any other Kconfig combinations which might
trip things up.
Yang Shi June 25, 2019, 10:30 p.m. UTC | #2 
On 6/25/19 3:14 PM, Andrew Morton wrote:
> On Thu, 13 Jun 2019 05:56:48 +0800 Yang Shi <yang.shi@linux.alibaba.com> wrote:
>
>> Currently shrinker is just allocated and can work when memcg kmem is
>> enabled.  But, THP deferred split shrinker is not slab shrinker, it
>> doesn't make too much sense to have such shrinker depend on memcg kmem.
>> It should be able to reclaim THP even though memcg kmem is disabled.
>>
>> Introduce a new shrinker flag, SHRINKER_NONSLAB, for non-slab shrinker.
>> When memcg kmem is disabled, just such shrinkers can be called in
>> shrinking memcg slab.
> This causes a couple of compile errors with an allnoconfig build.
> Please fix that and test any other Kconfig combinations which might
> trip things up.

I just tested !CONFIG_TRANSPARENT_HUGEPAGE, but I didn't test 
!CONFIG_MEMCG. It looks we need keep the code for !CONFIG_MEMCG, will 
post the corrected patches soon.
diff mbox series

Patch

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 9443caf..e14f68e 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -69,10 +69,8 @@  struct shrinker {
 
 	/* These are for internal use */
 	struct list_head list;
-#ifdef CONFIG_MEMCG_KMEM
 	/* ID in shrinker_idr */
 	int id;
-#endif
 	/* objs pending delete, per node */
 	atomic_long_t *nr_deferred;
 };
@@ -81,6 +79,7 @@  struct shrinker {
 /* Flags */
 #define SHRINKER_NUMA_AWARE	(1 << 0)
 #define SHRINKER_MEMCG_AWARE	(1 << 1)
+#define SHRINKER_NONSLAB	(1 << 2)
 
 extern int prealloc_shrinker(struct shrinker *shrinker);
 extern void register_shrinker_prepared(struct shrinker *shrinker);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7acd0af..62000ae 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -174,8 +174,6 @@  struct scan_control {
 static LIST_HEAD(shrinker_list);
 static DECLARE_RWSEM(shrinker_rwsem);
 
-#ifdef CONFIG_MEMCG_KMEM
-
 /*
  * We allow subsystems to populate their shrinker-related
  * LRU lists before register_shrinker_prepared() is called
@@ -227,16 +225,6 @@  static void unregister_memcg_shrinker(struct shrinker *shrinker)
 	idr_remove(&shrinker_idr, id);
 	up_write(&shrinker_rwsem);
 }
-#else /* CONFIG_MEMCG_KMEM */
-static int prealloc_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)
@@ -579,7 +567,6 @@  static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
 	return freed;
 }
 
-#ifdef CONFIG_MEMCG_KMEM
 static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
 			struct mem_cgroup *memcg, int priority)
 {
@@ -587,7 +574,7 @@  static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
 	unsigned long ret, freed = 0;
 	int i;
 
-	if (!memcg_kmem_enabled() || !mem_cgroup_online(memcg))
+	if (!mem_cgroup_online(memcg))
 		return 0;
 
 	if (!down_read_trylock(&shrinker_rwsem))
@@ -613,6 +600,11 @@  static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
 			continue;
 		}
 
+		/* Call non-slab shrinkers even though kmem is disabled */
+		if (!memcg_kmem_enabled() &&
+		    !(shrinker->flags & SHRINKER_NONSLAB))
+			continue;
+
 		ret = do_shrink_slab(&sc, shrinker, priority);
 		if (ret == SHRINK_EMPTY) {
 			clear_bit(i, map->map);
@@ -649,13 +641,6 @@  static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
 	up_read(&shrinker_rwsem);
 	return freed;
 }
-#else /* CONFIG_MEMCG_KMEM */
-static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
-			struct mem_cgroup *memcg, int priority)
-{
-	return 0;
-}
-#endif /* CONFIG_MEMCG_KMEM */
 
 /**
  * shrink_slab - shrink slab caches