Re: [RFC 06/10] Reclaim memory from blocked kernel stacks

[Steven Rostedt]

On Mon, 31 Aug 2026 08:55:09 +0200
Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote:

> Does this stack tracer distinguish between the kernel-stack and
> IRQ-stack?

It should only look at kernel-stack and not the irq stack. This stack trace
may have triggered when the interrupt put back the kernel stack, as it is
in the irqentry_exit code and about to do a schedule. The code has:

kernel/trace/trace_stack.c:

	/* we do not handle interrupt stacks yet */
	if (!object_is_on_stack(stack))
		return;

Which returns if the object is on the kernel-stack, and here "stack" is the
parameter passed into this function.

> I would expect asm_sysvec_apic_timer_interrupt() on the
> IRQ-stack and not adding weight to the kernel stack.

Right. But I believe this is where it switched back to the kernel-stack.

> Given how close this is to 8192, I don't think two stack pages will
> happen soon.

Agreed :-(

-- Steve