WARNING: lock held when returning to user space in set_property_atomic

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    903b77c63167 Merge tag 'linux-kselftest-4.21-rc1' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12d0f553400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=53a2f2aa0b1f7606
dashboard link: https://syzkaller.appspot.com/bug?extid=6ea337c427f5083ebdf2
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=120d906f400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1024673b400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6ea337c427f5083ebdf2@xxxxxxxxxxxxxxxxxxxxxxxxx

RBP: 00007ffe369ca7a0 R08: 0000000000000001 R09: 00000000004009ce
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000

================================================
WARNING: lock held when returning to user space!
4.20.0+ #174 Not tainted
------------------------------------------------
syz-executor556/8153 is leaving the kernel with locks still held!
1 lock held by syz-executor556/8153:
 #0: 000000005100c85c (crtc_ww_class_acquire){+.+.}, at:  
set_property_atomic+0xb3/0x330 drivers/gpu/drm/drm_mode_object.c:462


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