5.15.160 kernel causes suspend failure

I just upgraded to 5.15.160 kernel (Slackware64 15.0), along with a bunch of updates from the last month or so.

But now I cannot sleep the system. When I try to sleep (using KDE->Sleep or /bin/loginctl suspend), it goes blank for a while, and then just immediately resumes. When I checked dmesg, I found this:

> Freezing of tasks failed after 20.000 seconds (9 tasks refusing to freeze, wq_busy=0)

The culprit tasks are: lockd (x1), nfsd (x8). Each of these has a message like this:

kernel: task:lockd state:I stack: 0 pid: 1567 ppid: 2 flags:0x00004000
kernel: Call Trace:
kernel: <TASK>
kernel: __schedule+0x2d1/0x1380
kernel: ? kernel_accept+0x8e/0xb0
kernel: ? svc_udp_recvfrom+0x420/0x4a0
kernel: schedule+0x72/0x110
kernel: schedule_timeout+0x11d/0x160
kernel: svc_recv+0x747/0x810
kernel: lockd+0xa9/0x1d0
kernel: ? preempt_count_add+0x70/0xa0
kernel: ? _raw_spin_lock_irqsave+0x19/0x50
kernel: ? set_grace_period+0x90/0x90
kernel: kthread+0x13e/0x170
kernel: ? set_kthread_struct+0x50/0x50
kernel: ret_from_fork+0x1f/0x30
kernel: </TASK>

If I revert to kernel version 5.15.145, sleep / resume all works fine.

Any ideas or suggestions what might be wrong and how to fix it?