Re: [linux-next20260529] kernel BUG at kernel/sched/core.c:7512!

[Peter Zijlstra <peterz@infradead.org>]

On Mon, Jun 01, 2026 at 02:46:24PM +0530, Shrikanth Hegde wrote:

> Ritesh, Mukesh, Is below possible scenario?
> 
> do_page_fault seems to enable irq's in the interrupt handler?
> is that expected? if so, one might see
> 
> -- do_page_fault (enter kernel mode)
>    -- enables interrupts
>    -- gets interrupt - Sets need_resched.
>       -- irqentry_exit - Sees it is kernel mode. Just checks preempt count
> 			 and calls preempt_schedule_irq, which catches both
> 			 preempt_count and !irqs_disabled. Hence the panic?
> 
> Should do_page_fault do preempt_disable when it enables the interrupts?

No, it is expected for page-fault to be able to schedule. Specifically,
it must be able to sleep to support loading pages from disk.

Please check the value of preempt_count() (does it perchance have
HARDIRQ_OFFSET?). Also, if the fault handler does enable IRQs, it must
also disable them again once done.

Notably, I see ___do_page_fault() do interrupt_cond_loadl_irq_enable(),
but I'm not seeing a local_irq_disable() to match!