On 03/19, David Howells wrote:
>
> --- a/security/keys/gc.c
> +++ b/security/keys/gc.c
> @@ -218,8 +218,10 @@ static void key_garbage_collector(struct work_struct *work)
> key = rb_entry(cursor, struct key, serial_node);
> cursor = rb_next(cursor);
>
> - if (refcount_read(&key->usage) == 0)
> + if (test_bit(KEY_FLAG_FINAL_PUT, &key->flags)) {
> + smp_mb(); /* Clobber key->user after FINAL_PUT seen. */
> goto found_unreferenced_key;
> + }
>
> if (unlikely(gc_state & KEY_GC_REAPING_DEAD_1)) {
> if (key->type == key_gc_dead_keytype) {
> diff --git a/security/keys/key.c b/security/keys/key.c
> index 3d7d185019d3..7198cd2ac3a3 100644
> --- a/security/keys/key.c
> +++ b/security/keys/key.c
> @@ -658,6 +658,8 @@ void key_put(struct key *key)
> key->user->qnbytes -= key->quotalen;
> spin_unlock_irqrestore(&key->user->lock, flags);
> }
> + smp_mb(); /* key->user before FINAL_PUT set. */
Can't resist, smp_mb__before_atomic() should equally work,
but this doesn't really matter, please forget.
> + set_bit(KEY_FLAG_FINAL_PUT, &key->flags);
> schedule_work(&key_gc_work);
I believe this patch is correct,
Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx>
