syzbot has bisected this issue to:

commit 1a33e10e4a95cb109ff1145098175df3113313ef
Author: Cong Wang [off-list ref]
Date:   Sun May 3 05:22:19 2020 +0000

    net: partially revert dynamic lockdep key changes

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=10434970900000
start commit:   d8b9faec Merge tag 'drm-fixes-2020-07-31' of git://anongit..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=12434970900000
console output: https://syzkaller.appspot.com/x/log.txt?x=14434970900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c0cfcf935bcc94d2
dashboard link: https://syzkaller.appspot.com/bug?extid=3b165dac15094065651e
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=163e2c92900000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=143f2bb8900000

Reported-by: syzbot+3b165dac15094065651e@syzkaller.appspotmail.com
Fixes: 1a33e10e4a95 ("net: partially revert dynamic lockdep key changes")

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