Re: [PATCH] mm: might_sleep warning

[Pavel Tatashin]

> 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?

Thank you,
Pavel