5.4-rc1 hangs early on boot for me; the stack trace that I could
manage to see on screen suggested something kmemleak related, and it
was fairly quick to bisect it down to commit c5665868183f ("mm:
kmemleak: use the memory pool for early allocations").

Several call stacks periodically go by on screen, an interesting one
is (manually transcribed):

RIP: 0010:_raw_write_unlock_irqrestore+0x15/0x20
  find_and_remove_object+0x84/0x90
  delete_object_full+0x10/0x20
  __kmemleak_do_cleanup+0x2d/0x50
  kmemleak_do_cleanup+0x59/0x60
  process_one_work+0x1a4/0x3c0
  worker_thread+0x50/0x3c0
...

Config is attached.

Thanks,
Marc