4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shaohua Li <shli@xxxxxx> [ Upstream commit d939cdfde34f50b95254b375f498447c82190b3e ] Commit 03a9e24(md linear: fix a race between linear_add() and linear_congested()) introduces the warnning. Acked-by: Coly Li <colyli@xxxxxxx> Signed-off-by: Shaohua Li <shli@xxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/md/linear.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/md/linear.c +++ b/drivers/md/linear.c @@ -223,7 +223,8 @@ static int linear_add(struct mddev *mdde * oldconf until no one uses it anymore. */ mddev_suspend(mddev); - oldconf = rcu_dereference(mddev->private); + oldconf = rcu_dereference_protected(mddev->private, + lockdep_is_held(&mddev->reconfig_mutex)); mddev->raid_disks++; WARN_ONCE(mddev->raid_disks != newconf->raid_disks, "copied raid_disks doesn't match mddev->raid_disks");