[alsa-devel] WARNING in port_delete

[syzbot]

syzbot has bisected this bug to:

commit 63d86a7e85f84b8ac3b2f394570965aedbb03787
Author: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
Date:   Tue May 1 20:08:46 2018 +0000

     rcu: Convert rcu_grace_period_init tracepoint to gp_seq

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=17f86d2f200000
start commit:   091a1eaa Merge branch 'akpm'
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=14046d2f200000
console output: https://syzkaller.appspot.com/x/log.txt?x=10046d2f200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb
dashboard link: https://syzkaller.appspot.com/bug?extid=e4c8abb920efa77bace9
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=102e2c91400000

Reported-by: syzbot+e4c8abb920efa77bace9 at syzkaller.appspotmail.com
Fixes: 63d86a7e85f8 ("rcu: Convert rcu_grace_period_init tracepoint to  
gp_seq")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection