That's why page_alloc_init_late() needs spin_lock_irq(). If a CPU is holding deferred_zone_grow_lock with enabled interrupts and an interrupt comes in on that CPU and the CPU runs deferred_grow_zone() in its interrupt handler, we deadlock. lockdep knows about this bug and should have reported it.
I see what you are saying. Yes you are correct, we need spin_lock_irq() in page_alloc_init_late(). I will update the patch. I am not sure why lockdep has not reported it. May be it is initialized after this code is executed?
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