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WARNING: lock held when returning to user space!
4.14.307-syzkaller #0 Not tainted
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syz-executor.0/12219 is leaving the kernel with locks still held!
1 lock held by syz-executor.0/12219:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<ffffffff838df0d7>] lo_ioctl+0x87/0x1cd0 drivers/block/loop.c:1419
netlink: 16 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 16 bytes leftover after parsing attributes in process `syz-executor.4'.