Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
memcg: fix css_id() RCU locking for real
Commit ad4ba37 ("memcg: css_id() must be called under rcu_read_lock()") modifies memcontol.c for fixing RCU check message. But Andrew Morton pointed out that the fix doesn't seems sane and it was just for hidining lockdep messages. This is a patch for do proper things. Checking again, all places, accessing without rcu_read_lock, that commit fixies was intentional.... all callers of css_id() has reference count on it. So, it's not necessary to be under rcu_read_lock(). Considering again, we can use rcu_dereference_check for css_id(). We know css->id is valid if css->refcnt > 0. (css->id never changes and freed after css->refcnt going to be 0.) This patch makes use of rcu_dereference_check() in css_id/depth and remove unnecessary rcu-read-lock added by the commit. Signed-off-by: KAMEZAWA Hiroyuki <[email protected]> Cc: "Paul E. McKenney" <[email protected]> Cc: Daisuke Nishimura <[email protected]> Cc: Balbir Singh <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
- Loading branch information