[PATCH RFC 03/10] mm: Convert shrinker_rwsem to mutex

Kirill Tkhai
2018-08-07T15:38:21Z

There are no readers, so rwsem is not need anymore.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
mm/vmscan.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9dda903a1406..2dc274a385b9 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -167,7 +167,7 @@ int vm_swappiness = 60;
unsigned long vm_total_pages;

static LIST_HEAD(shrinker_list);
-static DECLARE_RWSEM(shrinker_rwsem);
+static DEFINE_MUTEX(shrinker_mutex);
DEFINE_STATIC_SRCU(srcu);

#ifdef CONFIG_MEMCG_KMEM
@@ -192,7 +192,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker)
{
int id, ret = -ENOMEM;

- down_write(&shrinker_rwsem);
+ mutex_lock(&shrinker_mutex);
id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL);
if (id < 0)
goto unlock;
@@ -208,7 +208,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker)
shrinker->id = id;
ret = 0;
unlock:
- up_write(&shrinker_rwsem);
+ mutex_unlock(&shrinker_mutex);
return ret;
}

@@ -218,9 +218,9 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)

BUG_ON(id < 0);

- down_write(&shrinker_rwsem);
+ mutex_lock(&shrinker_mutex);
idr_remove(&shrinker_idr, id);
- up_write(&shrinker_rwsem);
+ mutex_unlock(&shrinker_mutex);
}
#else /* CONFIG_MEMCG_KMEM */
static int prealloc_memcg_shrinker(struct shrinker *shrinker)
@@ -405,10 +405,10 @@ void free_prealloced_shrinker(struct shrinker *shrinker)

void register_shrinker_prepared(struct shrinker *shrinker)
{
- down_write(&shrinker_rwsem);
+ mutex_lock(&shrinker_mutex);
list_add_tail_rcu(&shrinker->list, &shrinker_list);
idr_replace(&shrinker_idr, shrinker, shrinker->id);
- up_write(&shrinker_rwsem);
+ mutex_unlock(&shrinker_mutex);
}

int register_shrinker(struct shrinker *shrinker)
@@ -431,9 +431,9 @@ void unregister_shrinker(struct shrinker *shrinker)
return;
if (shrinker->flags & SHRINKER_MEMCG_AWARE)
unregister_memcg_shrinker(shrinker);
- down_write(&shrinker_rwsem);
+ mutex_lock(&shrinker_mutex);
list_del_rcu(&shrinker->list);
- up_write(&shrinker_rwsem);
+ mutex_unlock(&shrinker_mutex);

synchronize_srcu(&srcu);