syzbot has bisected this bug to:

commit d665c1281bc89ac85b8b0c058c22a3f94640a1d6
Author: Yi Wang [off-list ref]
Date:   Mon Oct 21 23:57:42 2019 +0000

     net: sched: taprio: fix -Wmissing-prototypes warnings

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=132ee536e00000
start commit:   89d57ddd Merge tag 'media/v5.5-1' of git://git.kernel.org/..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=10aee536e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=172ee536e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=595c15c951695d1b
dashboard link: https://syzkaller.appspot.com/bug?extid=a229d8d995b74f8c4b6c
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1511af5ee00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16e0f17ae00000

Reported-by: syzbot+a229d8d995b74f8c4b6c@syzkaller.appspotmail.com
Fixes: d665c1281bc8 ("net: sched: taprio: fix -Wmissing-prototypes  
warnings")

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