For now, reparent_shrinker_deferred() is the only holder of read lock of
shrinker_rwsem. And it already holds the global cgroup_mutex, so it will
not be called in parallel.
Therefore, in order to convert shrinker_rwsem to shrinker_mutex later,
here we change to hold the write lock of shrinker_rwsem to reparent.
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
---
mm/shrinker.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/shrinker.c b/mm/shrinker.c
index ad64cac5248c..471c07d75c4a 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -292,7 +292,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg)
parent = root_mem_cgroup;
/* Prevent from concurrent shrinker_info expand */
- down_read(&shrinker_rwsem);
+ down_write(&shrinker_rwsem);
for_each_node(nid) {
child_info = shrinker_info_protected(memcg, nid);
parent_info = shrinker_info_protected(parent, nid);
@@ -305,7 +305,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg)
}
}
}
- up_read(&shrinker_rwsem);
+ up_write(&shrinker_rwsem);
}
#else
static int shrinker_memcg_alloc(struct shrinker *shrinker)
--
2.30.2
