On 2018/08/08 20:51, Kirill Tkhai wrote: > @@ -192,7 +193,6 @@ static int prealloc_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_REGISTERING, 0, 0, GFP_KERNEL); > if (id < 0) > goto unlock;
I don't know why perf reports down_read_trylock(&shrinker_rwsem). But above code is already bad. GFP_KERNEL allocation involves shrinkers and the OOM killer would be invoked because shrinkers are defunctional due to this down_write(&shrinker_rwsem). Please avoid blocking memory allocation with shrinker_rwsem held.
