| Message ID | 20230911094444.68966-45-zhengqi.arch@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | use refcount+RCU method to implement lockless slab shrink | expand |
> On Sep 11, 2023, at 17:44, Qi Zheng <zhengqi.arch@bytedance.com> wrote: > > 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@bytedance.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Thanks.
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)
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@bytedance.com> --- mm/shrinker.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)